29:1-

FLORAL STRUCTURE AND STAMENS IN BO2~IBAX CE[BA L.

BY T . A . Daws

[,Ldian Statistical Institute, (,,'a[cul!a- 35

From the aestivation ofBombax ceiba, two kinds ol'flowers (left-handed and right-handed) are distinguishable, and in a plant Llle two types O c c u r i l l almost the same proportion. The mean number of stamens per flower ranges fi'om 62.72 to 102-00, and this variation is mostly clue to the variation in the number of stamens of the five peripheral staminal bundles of a flower. The central bundle has almost invariably 5 long stamens and | 0 slightly shorter ones, and variation in their number is the least. There is no significant difference in the number of stamens between a left-handed and a right-handed flower and their fi'uits weigh almost the same. Also the mtmbers of their seeds do not differ statistically significantly.

NOMENCL&TURE OF l~onlb(lX ceiba

Bombax ceiba, belonging to the Bombacaceae (included under Maivaceae by Hooker, 1872), has drawn much attention from systematists, and consequently the species has had several names. To the genus Bombax, Linnaeus assigned three species--B, ceiba, B. penta~a'trum and B. rel@iosum (Species Plalitarum, 1753, pp. 511-512). Recent work by Robyns (I961, 1963) advocates tlmt this species should be called Bombax ceiba. For further information on the nomenclature of this species, the works of Bakhuizen van den Brink (1924), Green (1929), Furtado (1939), Dugand (1945), Chattmjee and Raizada

(t950, 1954), which are discussed by Robyns (1961), are useful. Some important synonyms for the species are Bombax heptaphyt[um, B. malabaricum, Salmalia malabarica, Gossampinus rztbra, G. heptaphytla and G. iVialabarica.

Whether it is to be regarded as an American species or an Asiatic one, Bombax ceiba grows luxuriantly in the tropical regions of India and Burma except in arid tracts. It

flourishes in the sub-Himalayas upto 3,500 ft. (cultivated at 6,000 ft. in North-west HimaIayas, S,'ilim All, 1932). I t is a very common plant throughout Maharashtra and Saurastra and all the forest districts of Madras and Andhra, and to a limited

extent in Kerala. I t is one of the most conspicuous trees of West Bengal, particularly during January-April every year on account of its very bright, large red flowers. The species is also distributed in Ceylon, Malaysia, Indonesia, Qneensland and North

Australia. In India the plant is known as the red silk-cotton tree to distinguish it fi'om Ceiba

pentaIMra, the real silk cotton (Kapok or white silk cotton) tree.

AESTIVATION OF 'F~[E COROLLA

The corolla of a flower of this plant is clearly twisted in the bud, which condition is more distinct when the flower opens. A striking peculiarity of the aestivation is that

in about half the number of flowers of any individual plant or any large flowering shoot

T. A. DAvis 295

i ' I . . X T E 2 I

FMw,:rs of Bom/,a.x ~;ba 'h~,wh~g t i ! 2 h b h a ~ M c d (3 fl .x~cr~ *,t, tit,- L,'t* r - w i . a n d h.fld~zmch'cl pr'lal-I Wislg.

T . A . D A v i s 297

of a pImat, the petals are twisted clockwise and the rest in a comm-:r-clockwise l~Lshion,

a s i tuat ion conspicuous in tim Malvaceae (Davis, 1964a; Davis and Selvara3, 196-1-).

Fig'. 1 shows tin'ee r igh t -handed flowers c o m p a r e d with a similar munber of le f t -handed

ones. T h e ind iv idua l petals are somewhat asymmetr ica l (the two lowest flowers in.

the figure reveal this) and this charac te r according to Schumant~ (1886) and Rend le

(1959) is cor re la ted with twisted aestiv/ttion. When viewed apical ly , the flower is

considered le f t -handed (clockwise contor ted aest ivat ion) if the i n m r marg in of a petal

curves cloekwisely towards the per iphery and r igh t -handed , if it curves counter-

clockwisely. T h e s t igmat ic lobes usual ly show twisting in accordance with tha t of the

corolla. In a dr?, flower where all the petals are held together wiLh the stamens, the

petals r ema in sl ightly coiled according to the aestivation. Apar t from Bombax ceiba, right- and lef t -handedness was observed in the following 14 species ,,f the Bombacaceae ;

Admlsolzia digitata, Bombax albidum, B. ins@his, Ceiba pentandra (])avis and K u n d u , 1965), Ceiba rosea, Chorisia bzsignis, C. speciosa, C. grandiflora, Pachira aqz~atica, P. c~,athophora, P. insigl6s, P. lolNifolia , Pseudobombax grandiflorum and Salmatia insignis. Lawrence (1.963) assigns 22 genera and 140 species to this family.

PROPORTION OF LEFT- AND RIGHT-HANDED FLOWERS THROUGHOUT

THE BLOOMING PERIOD

In o rder to ascer ta in whether the left- and r igh t -handed l-low,.rs are p roduced in

equal p ropor t ions on a tree th roughout the b looming period, three t~ees s tanding wi th in

200 metres from each other, very near the Ind i an Statist ical Inst i tute, Ca lcu t t a were

marked and all the fowers that b loomed dur ing the 1962 season e: :amined. The d a t a

are presea ted in T a b l e 1. The flowers ofBombax ceiba possess largf quanti t ies of nec ta r which a t t r ac t qui te a lot of bii-d species and on one tree 1 counted a~ many as 17 species

on a day. T h e house crow (Corvus splendens) has a tendency to carry away a few flowers to an ad jo in ing tree before tearing a peta l or two to enable its bulk.~ beak to reach at the

nectar. I m a y have lost in this m a n n e r upto 3 per cent of the fl~,wers of these trees.

Whc table accounts tbr the rest of the flowers. Tim blooming period of tree I lasted

46 days and those of trees 2 and 3 lasted 3q. and 38 days respect!vet).

I( m a y be seen that there are more lef t -hande,s than r ight-handurs in all three trees

bu t the difference is significant for trees 1 and 3 only with X e s (each with 1 d.f.} being

6"78 and 22' 18 respect ively (P--0"01, 10-s). Fo r tree 2, X z is 4-67 ~ P-=0"I0).

The he te rogenei ty X" with 2 d.E to test the hypothesis that the propor t ion of left-

handers is the same for all the three trees turns out to be 8'44 (P :=001) . I t can be

concluded tha t the percen tage of lef t -handers is not the same for all '~hree trees.

The b looming per iod, which is near ly the same lbr all three tr~"s, was d iv ided into

4 equal quar te rs (Tab le 2) to see if there was any ind ica t ion th~,t the perccutagc of"

lef t -handers changes wi th time in tim blooming period. Since tl~ele does not secm

to bc ai~y g rea t difference among the percen tage of lef t -handers ft,- the tlu-cc trees

during lhe per iod as a whole, the da ta for the three trees can t~,: pooled and tested

for dift 'crences in the percentage of left-handers. This seems only reasonable as trees

of the same species standit~g close to each o ther are not expected {~, show any marked 5

298 Biomeby of Bombax ceiba Flowers

T a b l e I . B o m b a x c e i b a : Daily bloomblg in 3 trees

Tree I Tree 2 Tree 3

1962 Flowers Lefts ]~'lo;vers Lefts Flowers Lefts operled opened opened.

January

February

30 6 5 31 10 5

1 16 8 2 20 12 3 14. 6 4 42 21 t 1 5 t84 100 1 I 6 211 110 7 5 1 1 7 250 121 10 5 - - 8 202 95 12 4, - - 9 252 138 7 2 I !

I0 571 293 21 l l 1 1 11 708 344 43 25 4 1 12 729 373 66 37 4 4 I3 1124 581 102 49 7 5 14 1873 990 121 67 37 20 15 1472 730 129 63 83 51 16 1082 498 199 114 201 t08 17 978 457 144 71 172 102 18 1016 501 153 76 196 102 19 1370 687 176 90 358 208 20 1518 778 158 80 360 226 21 1788 943 205 116 395 187 22 1328 644 104 56 424 227 23 1118 555 85 42 458 228 24 843 445 84 42 526 271 25 1042 550 86 47 564 302 26 740 393 70 39 763 380 27 466 224 44 19 885 463 28 578 318 32 16 824 440

March l 267 140 21 8 ~.75 230 2 239 145 17 I0 358 193 3 285 152 22 12 293 i53 4 226 124 16 9 171 80 5 I88 88 II 4 125 6i 6 166 84 10 4 i47 70 7 135 69 7 6 107 56 8 102 48 I I 59 32 9 52 23 1 1 56 26

10 48 25 22 12 11 51 28 28 18 12 32 17 16 10 13 17 9 10 6 14 12 6 9 8 15 6 4 4 2 16 1 1

T o t a l 23378 11888 2166 1133 8145 4285 Percentage Le~s: 50.85 52.31 52.61

T. A. Davls

T a b l e 2. Bombax ceiba: Period of blooming and % of Lefts

299

Period Total Lefts % Lefts

Tree 1 1st Quarter 1,778 914 51.41

2ud Quarter 13,658 6,882 50"39

3rd Q.uar ter 7,132 3,690 51.74

Final Quarter 810 402 49.63

23,378 11,888 50.85

Tree 2 1st Quarter 168 91 54.17

2nd Quarter 1,182 610 51.61

3rd Quarter 710 377 53' 10

Final Qtrar ter 106 55 51-89

2,166 1,133 52.31

Tree 3 1st Quarter 138 84 60.87

2nd Quarter 3,090 1,659 53.69

3rd Quarter 4,4.59 2,302 51.63

Final Quarter 458 24.0 52.40

8,145 4,285 52.61

All trees 33,689 17,306 51-37

in te rac t ion with the quarters . )i 2 with 3 d.f. turns out to be qui te low (2.49) and

does not, therefore, indicate tha t the percentage of le f t -handers changes with time

dm-ing the b looming period.

T h e overal l X 2 with 11 d.f. to measure differences in the percentages of left-hander~.

for the 12 categories (3 trees >,4 quar te , s ) turns out to be 19-97 (P=0"046) thus sup-

por t ing the above conclusions.

D a t a on the b looming of" trees I and 3 on i\u' ther examina t ion show a very curiou~

d a y - t o - d a y i r regular i ty . For tree 1, on 33 days over 50 flowers opened (days witt,

smal ler n u m b e r of flowers are ignored) . X]~. =58-48 (P=0"003) which imptics ver,.

s ignif icant heterogenei ty . Fo r tree 3, there are 23 days on which over 50 flower,

opened , and ,~,~= for he terogenei ty tu rned to be 4.3-20 which is also very significm~,

( P = 0 - 0 0 5 ) . T h e conspicuous day - to -day variat ion in the p ropor t ion of lefts ar/d

rights is very difficult to expla in (Davis I964b).

NUMBER OF ~TAIVIENS IN LEFT- AND RIGIIT-HANDED I?LO~,VERS

T a M e 3 shows da ta on the total n u m b e r of stamens for left- a n d r igh t -handed flower>

of B. ombax ceiba. Small samples of flowers were drawn at weeldy intervals from thre, trees du r ing the 1962 season, and s tamen numbers counted. T h e mean s{amen mlmbc~

for the 540 flowers sampled was 70.17. Approx ima te ly ha l f the flowers sampled wet-,::

lef t -handers and the mean s tamen n u m b e r for lef t-handers was 69.93. This numbe~

300

Tab le 3.

Biometry of Bombax ceiba Flowers

B o m b a x ceiba: Number of stamens in Left- and Right-handed flowers (Data on 3 trees, season 1962)

Source Flowers Mean Stamens Free+2 Double examined

Free Double Mean variance

1. All flowers 540 67-49 1-34 70'17 30"01 Left-handers 272 67'35 1 "29 69"93 38"4.7 Right-handers 268 67.63 1.38 70.40 39.60

2. First week 150 68.97 1.88 72.73 60.48 Left-handers 75 68.65 1-72 72-19 55.78 Right-handers 75 69.19 2'04 73.27 65-41

3. Second week 150 67.86 I-4.1 70.69 41.32 Left-handers 75 67"91 1" 45 70.81 46- I 0 Right-hal(ders 75 67-81 1.37 70-56 37.06

4. Third week 147 66-68 0"93 68.53 20-18 Left-handers 74 66.26 0.91 68-07 18.86 Right-handers 73 67-11 0.95 69.00 21-36

5. Fourth week 93 65-78 I'00 67.78 10.54 Left- handers 4B 65' 96 0" 98 67.92 t 3.14 Right-handers 45 65-60 1 "02 67'64 7'96

does not differ s ignif icantly from the mean for r ight-handers (70.40). A t weekly

intervals also, both kinds of flowers bore a lmost the same number of stamens, a l though

the mean per flower decreased as the season progressed. Fur the r da ta on the pheno-

menon of reduct ion in s tamen n u m b e r with t ime are presented in Tab le 7. I n the

case of Hibiscus rosasinensis also, the number of s tamens of lef t -handed flowers d id not differ significantly from that of the r ight -handers , but the s tamen n u m b e r var ied

significantly with t ime (Davis and Ghoshal , 1965).

A perusal of the values in the last column of T a b l e 3 will reveal tha t the var iances

s teadi ly decrease with t ime (within the f lowering season extending for less than two

months) from 60.48 to 10-54.. This is in m a r k e d cont ras t with the phe nome non recorded

by Roy (1963) on the petal numbers of Nyctanthes arbor-tristis where the var iances rose s teadi ly with t ime dur ing the four -month b looming per iod, and were from 20% to 40%

grea ter a t the end of the season than the beginning. Similar increases in var iance of

peta l n u m b e r were also observed by him in Jasminum multiflorum.

CAPSULES FROM LEFT- AND ~--,.IGHT-HANDED FLOWERS

Dur ing the 1963 season, 38 fully developed capsules were harvested from one tree

jus t when they showed signs of dehiscence. O f these, 21 were fi'om lef t -handed flowers

and the rest from r igh t -handed ones. The capsules were sundried uni formly for a

fortnight and weighed. T h e numbers and weights of seeds were also est imated. Not

all seeds of a capsule were fully developed. T h e fertile (fully developed seeds) and the

defbrmed ones were accounted for separa te ly and the entire da ta are shown in T a b l e 4.

T a b l e 4.

T. A. DAVIS

B o m b a x c e i b a : Data on fruits from Left-and Right-handed ,/Towers I. Left-kandeds

301

Weights (gin.) of Number o | seeds FrLtils Wt. of capsule

(gin.) seeds cotton Fertile Detbmaed

1 2i'5,1. 5-09 5.93 t44 39 2 22.51 4.73 6'27 118 0 3 22"86 5"62 6-01 161 2 4. 26"22 6-41 6-96 211 25 5 20"13 3-93 5'14 254 18

6 22.95 5.81 5.94. 177 27 7 22-12 5.69 5-98 213 24 8 14..06 2.65 4-03 96 17 9 15.44 3-15 4.19 105 10

10 I4.09 2.48 3-65 87 0

I1 13-15 2"88 3"42 93 0 12 12-87 2"t7 3-25 110 7 13 16.45 3,25 4'53 I10 32 14 18.71 4,04 4.86 125 15 15 17.63 3-56 4.51 121 9

16 17-42 3-84 4-02 121 7 17 13-27 3'12 3.29 104 0 18 13-26 2.21 3'31 119 7 19 13"32 2"85 3"30 80 0 20 17"43 3-67 4'17 107 2

21 18.28 3.95 4.69 138 0

Total 373.7 ~ 81.10 97-4.5 2794 2-tl

),'[can 17,796 3.862 4'640 133.05 11 '4.8

IL Right-handed~

l 154.2 3'13 4-17 9o 0 2 1655 3"03 4"64 106 4 3 I 8.3ti 3-35 486 112 0 4 14.9i 2.50 3.78 14-6 16 5 1535 3.11 424 99 12

6 17-38 3 55 4.'89 I i 7 14 7 13-1.I 3-05 3-88 96 0 8 1625 3'62 4-56 19-t- 31 9 2082 3'56 6-02 133 I t 5

It) 25-21 6-51 6'58 197 45

11 I,I-83 2-73 ,I.'35 89 4 12 16.23 332 4..60 111 0 13 18'92 ,t-.20 54.1 154. 5 I 14 19.72 ,I-.07 5.45 I ,I 3 5 I 15 16.26 3-32 4-73 105 32

16 21.57 ,t..57 5-73 153 23 17 13 1 I 2'33 4.09 107 20

Total 29,14)5 59.95 81-98 2157 418

Mean 17.297 3"526 4"822 12~188 2't "59

L--l~. oa mean 0-499 0"336 --0" 182 6' 17 - 13'1 I

302 Biometry of Bombax ceiba Flowers

The differences in the weights of the entire fl-uit, or of the seeds and flint between the two types of fruits are not significant. The left-handers possess 4"86 pex" cent more seeds than their counterpart. ']'he difference between rights and lefts with respect to the number of sterile seeds is largely due to capsule 9, with 45 per cent sterile seeds. Even excluding this, however, the excess of capsules with sterile seeds on the right is significant (X~ =37-6). I f the capsules are divided into those with more and less

than 10% sterile seeds, one finds the following.

Over lO% U~2der 10% steri~ s~ri~

Right 10 7 I7

5gt 7 14 2l

17 21 38

~ = 0 " 4 2 . This is insignifican.t.

DEVELOPMENT OF THE COROLLA

Serial sections were prepared from the apex of the fleshy pedicel upwards of several left- and right-handed flowers to examine how the aestivatiort in them develops. Fig. 2 shows six main stages before the initials of the corolla are well-defined. The numerous vascular traces are seen arranged as a ring, and at various intervals, a few traces are seen div&ging tO the periphery giving connections to minute appendages seen on the surface of the thalamus just below the fleshy calyx cup. These perhaps represent the reduced eplcalyx present in many malvaceous species. The conti~auity of the ring is ~ost (stages 2 and 3) when some traces proceed to the periphery. I a stages 4 a n d 5 , they are brought together as a wavy ring. In stage 6, initials of the gynoecium are just formed. The ring of vascular traces at this stage breaks into five curved strips whiIe several traces diverge to the periphery to reinforce the calyx cup. In Fig. 3, the de- velopment of the five strips which form the petaI-stamen cord upto the stage where

the petals are clearly distinguished are shown. "/'hose along the left row are from a right-handed flower and those in the right row are of a left-handed flower.

At stage 1, the five broken cords form semicircular arcs with their convex surface.~ facing the lJeriphery of the flower. The arcs become more pronounced in the next stage. At stage 3, each arc has broken into a unit of three. The distal ends, curving in, detach fi'om the mai~ arc. The main are develops into a petal and the inner two portions of the petal-stamen cord develop into stamens. The relative positions of the two inner traces to the bigger outer one has some significance. I f a line is drawn (indicated in two figures) fi'om the centre of the flower right through the gap between the two inner traces, the petal-trace (or most of it) will be seen remaining either to the left or the right side of the line. This is the situation in all five units. This lies more to the left in a right-handed flower and vice versa. In the next stage, each petaI-trace

T. A. DAvis 303

Fig. 2. ,Stages iu the (l~.~,clopmcnt of petal-stamen cord of a B . ceiba flower.

304 Biome6y of Bombax ceiba Flowers

Fig. 3, Difli2rentiation oF tile corolla fi'om the petal-stamen cord in tL~ right-handed (left-row) and left-handed flowers of B. ceiba.

T. A. DAVIS 305

is seen d iv id ing radially and the petals just begin to be formed. With further radial divisions o f these traces which ultimately form almost a ring, the five petals are clearly

dist inguishable, their fi'ee ends overlapping the petals to their right or left according to

the type of flower.

THE ANDROECIUM

The a n d r o e c i u m of the Bombacaceae is interesting and highly variable from species

to species. T h e number of stamens varies from five to about one thousand in different

species, and R o b y n s (1963) has given considerable importance to this numerical varia-

tion in his classification of the genus Bombax. Bombax ceiba is even more peculiar in that

a flower has three kinds of stamens (Davis and Mar i amma, 1965). The stamens are

fused at the base into a short monadelphous tube to which the bases of the succulent

petals are a t t a ched in such a way that when the flower withers, the calyx cup, the corolla

and the s tamens shed together. T he androec ium consists of five peripheral staminal

bundles w h i c h form a ring around the internal verticil. The number of stamens per

peripheral b u n d l e varies considerably and in a flower all five bundles do not necessarily

bear the same n u m b e r of stamens. T h e central verticil consists of two kinds of stamens and they differ also in length. T he five innermost stamens though free almost to

the base, envelop the style. Each of these stamens must be regarded as a double

stamen, since it bears two distinct anthers. There is a prominent groove on the fi lament

which is fu r the r suggestive of the s tamen being a fusion of two. In many such stamens, the fi laments separate into two at the tip, each carrying an anther. There are ten

more s tamens at the verticil which are slightly shorter than the inner five, and they

partially cover the latter. Each of these stamens has a single anther which

is reni ibrm or more often coiled, the ends overlapping each other. The anthers

of the cen t ra lmos t five stamens are slightly bigger than the others and their coiling is more p ronounced . The pollen grains of the innermost stamens are larger than those

of the o ther two. A peripheral bundle m a y be considered as sharing three stamens of

the central verticil of which two belong to the shorter kind and one to the.longer. The

number of s tamens of the central bundle is invariably 15 and the variation in the n u m b e r

of stamens per flower is due mostly to the peripheral hundles. A peripheral bundle

curves sIightly and the convex surface facing the petal (as can be expected) has a greater

number of stamens. Stamens are pluriseriate and are commonly united at the base. Each b r a n c h usually forks into two, each ultimate unit bearing an anther, and thus a normal s t amen m a y be regarded as split: into two halLstamens. Such a splitting of

stamens is termed ehorisis' by Velenovsky (1910).

VARIATION IN STAMEN NvMm.;v.

Flowers fl 'om 53 trees of Bombax ceiba were examined f,_w tlle number of stamens

during tile last five flowering seasons (1962-66). The trees are fi'om tile 24 Parganas and Hoogh /y districts of West Bengal covering almost a rectangular region measur ing

306 Biometry o j" Bombax ceiba Flowers

a b o u t 150 k m .'

&

<

i+ _ 0

ud

B ~

, ~ " G

o~'~ d"~ E', +

lJ m + ~

--=+-, .~2

W. A. DAWS

o o ~ o o o o o ~ o o o o o o o o ~ o ~ o o 6 6 6 6 6 6 6 6 6 6 6 6 6 0 6 6 6 6 6 6 6 o o o o

. . . . . m + . . . m -

6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 ~ 6 6 6 6 6 ~

F-

~Z

r cD

O I c-I ~-c O l C,I

307

3{)8 Biometry of Bombax ceiba Flowers

c o l l e c t e d f lowers a t w e e k l y i n t e r v a l s d u r i n g a f l o w e r i n g s e a s o n a n d c o u n t e d t h e i r

s t a m e n n u m b e r s . T h e d a t a a r e g i v e n in T a b h : 6. T h e m e a n m t m b e r s o f s t a m e n s for

t h e e n t i r e perio~l for i n d i v i d u a l t rees a r e a l so g i v e n in t h e T a b l e . T h e m e a n fo r a

t t c c v a r i e s f r o m 65"971 to 99. 186. ' F rees 2:1 a n d l g p r o d u c e h i g h p e r c e n t a g e s o f d o u b l e

s t a m e n s . A p e r u s a l o f c o l u m n (g) o f t h e T a b l e veil[ s h o w t h a t t h e m o d e s for 19 o f t h e

2 4 t rees l'all a t 65 , 75 o , 85. A t l e a s t t wo m o r e t r ees w i I [ / ' a l l i n t o t h e a b o v e g r o u p i f

t h e v a r i a t i o n in t h e c e n t r a l b u n d l e is i g n o r e d . S i n c e t h e c e n t r a l b u n d l e h a s t h e r a t h e r

c o ~ , s t a n t n u m b e r o f 15 s t a m e n s , e x c l u d i n g t h e s e , t h e a b o v e t r ees wil l b e s e e n to p o s s e s s

50 , 60 o r 70 s t a m e n s p e r f l o w e r a n d t h e s e s t a m e n s a r e f i ' om t h e f ive p e r i p h e r a l b u n d l e s .

I f t h e s e n u m b e r s a r e d i v i d e d b y t h e n u m b e r o f b u n d l e s , a p e r i p h e r a l b u n d l e wi l l h a v e

10, t2 o r 14 s t a m e n s o n a n a v e r a g e . T h i s p e c u l i a r i t y is f u r t h e r b r o u g h t o u t b y t h e

g r a p h (Fig . 7) a n d T a b l e 14. T h e 532}~ f l o w e r s a c c o u n t ~)r '4.00139 s t a m e n s o r

ro t~gh ly 75 s t a m e n s pet" f l o w e r .

T a b l e 7. l ? , o m b a x c e i b a : Weekly mean number of stametzs (per.flower) in 24 lrees

~r intervals

Trees 1 2 3 4 5 6

1 67"36 67.04 65.08 63.98 64.25 . .

2 67.54 66-54. 6 5 - , 1 . 0 . . . . . .

3 67.56 67-38 69.2-1- 67-00 65.92 66.27

4 69-20 67.22 65.20 . . . . . .

5 67.08 67-9,1- 67"70 68.00 . . . .

6 69"80 69"36 67..54. 65.72 . . . .

7 73-28 71"56 70.20 70'25 . . . .

8 74"40 72"52 70'72 67"70 . . . .

9 75-22 75'05 72-40 67"88 66"06 �9 .

10 74.36 73-68 72.32 66.50 65"00 . .

I 1 73-94 72-36 74.00 70.01 . . . .

12 74. I2 74-44 73.02 73' 14- . �9 �9 �9

t3 74.16 7,1.68 73.56 73.84 68.50 �9 �9

I4 74.12 73"90 72-80 . . . . . .

15 76-34 75.68 72.76 70.00 . . . .

16 85.63 78" 18 71-52 71.90 . . . .

17 78-84 78.74 74..00 72.00 . . . .

18 81.94 80"1-6 76.12 72"56 70.92 . .

19 76-29 77-36 ~i.06 . . . . . .

20 80.,1-2 80-,1'8 76.63 . . . . . .

21 80.02 81.88 83-14 80.07 . . . .

22 83-54 81-93 83.04 83-62 . . . .

23 89.82 90.13 89-38 89.6~f �9 �9 �9 -

24 103-18 102-76 99.46 96.44 94'66 95"63

T. A. DAws 309

NUMBER OF STAMENS A'r ~,A, rEEKLY INTEIIVALS IN ~d" TREES

D e p e n d i n g on the dura t ion of" b looming of a tree, flower samples were collected

fi-om the 24 trees and the sampl ing ranged fi'om three to six weekly intervals (vide

Tab le 7). In ten trees the mean s teadi ly d ropped with t ime: T h e fall in the mean is

pa r t i cu la r ly str iking for trees 9, 10, I6 and 18, wlaieh is as much as 12'2, 12-6, 16"0 and

13-4 per cent respect ively of the init ial n u m b e r of stamens. O n l y in one tree (19)

does the mean s teadi ly increase with t ime and this t rend is seen for the first three weeks

for tree 21 which aga in shows a d rop in the fourth and last week. No obvious pa t te rn

is seen for the rest of the trees and the means vary irregularly.

T a b l e 8. Bombax ceiba: Stamens per jIowerfrom three main shoots of the same tree

Tree Shoot Mean \;ariance

I 68.32 8.22 2 68.39 6.54 3 67.16 4-05

1 96.32 179-18 2 96.00 24-60 3 94.86 18-72

1 7t.18 12-31 2 70-,I-4 7-85 3 70-44 8.05

NUMBEI-~S OF STAMENS IN FLOWERS ON DIFFERENT SHOOTS OF A TREE

To see whe the r the flowers on differel~t large flowering shoots of a tree prodt~ced

the same n u m b e r of s tamens or not, flowers from three trees were examined il~ 1964.

In each tree 50 flowers each fi-om three large branches were collected and the total

n u m b e r of s tamens counted. T h e da t a are presented in T a b l e u.~ The variat ion

in the mean numbers of s~amens between shoots is not s tat is t ical ly sigrfificarLt. Snmc

of the b ranches of tree 24 (Table 6) spread r ight over another tree whose flowers have

only 70 stameJ~s each and this i~dicates that the effect of the env i ronmen t on the mmlber

of s tamens per flower is not great .

INTENSITY OF FLO'WERING AND ]N~-UMBk;R OF STAME'NS

T a b l e 9 givc.~ da ta on the n u m b e r of s tamens per flower for three trees for 1962, 1963,

1964, 1965 arid 195(5. Whi le tree 2 p roduced almost the same n u m b e r of flowers dur ing

the five seasol~s, trees 1 and 3 behaved very differelnly in 1964. These trees stand wilhin

200 metres f iom each other and under appa ren t ly similar condi t ions. Tree 3 produced

only abou t one per cent of the normal number and tree 1 a b o u t seven percent. The-

cause lbv the severe d rop in p roduc t ion in the two trees is not known; tim trees are

perfect ly heal thy- looking. Per iodic i ty in flower product ion as met with in Jl,lmlgifera

310 Biomet O, of Bombax ceiba Flowers

Table 9. Bombax ceiba: Intensi~ qf.flowe~:ing and nlonber of slamcns

Season Particulars Trees A

1 2 3

bloomed 2,166 23,378 8,145 1962 No. of flowers

examined 150 200 193

Me:m number of stamens 64-67 67.89 75.70

bIoomed 2,200 25,000 8,500 1963 No. of tlowers

examined 270 341 263

Mean number of stamens 65"85 67'28 77.94

blooined 150 25,000 80 1964 -- No. of llowe;'s

examined 112 302 63

Mean number of stamens 65.33 68.34 77.27

bloomed 2,420 25,000 9,350 1965 No. of flowers

examined 263 300 283

lX.fean number of stamens 65-89 67.65 78.38

bIoomed 2,200 25,000 9,000 1966 No. of flowers

examined 160 196 162

Mean number of stamens 65.32 66.85 79.13

N.B. The s(:rial numbers given for the above trees are different from those given in Table 5 or 6.

indica or to a lesser degree in Cocos nucifera is not known to exist in Yombax ceiba. While the mean number of stamens for tree 2 dur ing 1964 was slightly higher t han the pre-

vious years, n'ees 1 and 3 produced almost the same numbers of s tamens as they did

in 1963, althc, ugh their productivi ty fell very ab rup t ly in I964. D u r i n g 1965 while

tree 2 produced the same n u m b e r offlowers, trees 1 and 3 produced abou t 1Q per cent

more than their product ion in 1963 and 1962. T h e mean s tamen n u m b e r s remained

the same, as can be seen in Tab le 9. I t is clear tha t the mean s tamen numbers.pm~

flower for the three trees do not vary significantly witl~ density of b looming. The figures

for 1966 only [brtify the above conclusion. Whi le examining the s tamen number s of

the three trees over five ?:ears, a gradual increase in the n u m b e r of s tamens is clearly

not iced for tree 3, a l though no such trend is seen with trees 1 and 2.

ANNUAL VARIATION IN THE NUMBER OF STAMENS

Stamen numbers for a few trees Were estimated dur ing the 1963 a nd 1964. seasons

and the figures for five trees are presented in Tab le 10. Only one tree (15) produced

more stamens ia 1964. For the rest, the differences arc not significant.

T a b l e 10.

T. A. DAvxs

B o m b a x c e i b a : A4ean mtmbers of stamens per flower of five trees during conseculive years

9 1 1

Stamens (mean) at weekly intervals Trees Season For the Vari-

1 2 3 4 5 6 7 season ance

1963 67.56 67.38 69-24 67.00 65.92 66.27 . . 67-28 6-81 3

1964. 68.54 68.24 68.66 68.56 68.32 67.84 66-00 68.34 10.40

1963 . . 67.08 67.94 67.70 68.00 . . ... 67-73 7-30 5

1964 69.65 69-30 69-26 68-82 67-63 66-79 . . 68.69 13.01

1963 74..36 73.68 72-32 66.50 65.00 . . . . 71.89 15-88 10

1964 71.60 71-74 70.18 68-59 65-60 . . . . 70.58 12.90

1963 74.16 76.68 73-56 73.8,t. 68.50 . . . . 73-77 9.60 I3

1964 73.90 73-30 74.12 73.27 71.47 . . . . 73-36 7.79

1963 76.34 75.68 72.76 70-00 . . . . . . 74.09 14..91 15

1964 78.30 76-26 73.95 68-67 . . . . . . 76.03 14.02

T a b l e 11. B o m b a x c e i b a : Aroma! variatiolz bz the number of stamens per flower for one lrec

Weekly interval 1962 1963 I96,1. 1965 1966 Mean for 5 s e a s o n s

First . . 67"56 68-50 68"36 . . 68' 14

Second 69-56 67.38 68"24 68.44 67.14 68.15

Thi rd 68"20 69"24 (~8'66 66"92 66"90 67"98

Four th 67"50 67'00 68-56 67'30 65-62 67'20

Fitih 66-30 65-92 68.32 67.68 67.80 67-20

Sixth . . 66.27 67-90 66"58 . . 66.92

For the season 67-89 67-28 68"36 67.65 66-85 6,7.65

(No. of flowers) (200) (270) (300) (300) (196) (1266)

I n T a b l e 1 1, d a t a h a v e b e e n g i v e n o n t h e m e a n n u m b e r s o f s t a m e n s p e r f l o w e r a t

w e e k l y i n t e r v a l s f o r o n e t r e e for f ive c o n s e c u t i v e s e a s o n s . T h e o v e r a l l m e a n is 6 7 . 6 5

s t a m e n s p e r f l o w e r . A l t h o u g h fo r 1 9 6 4 t h e m e a n is s l i g h t l y h i g h e r t h a n fo r t h e o t h e r

s e a s o n s , t h e d e v i a t i o n t i ' o m t h e o v e r a l l m e a n is n o t g r e a t a n d t h e d i f f e r e n c e n o t s i g n i -

t i c a n t.

"VARIATION IN THE NUMBER OF STAMENS PER PERIPHERAL BUNDLE

T i l e p e r i p h e r a l b u n d l e s o f 50 f l o w e r s f l ' o m 24 t r e e s w e r e e x a m i n e d d u r i n g t h e t i r s t

w e e k o f t h e i r b l o o m in 1964, t h o u g h m u c h larger d a t a w e r e c o l l e c t e d o v e r t h r e e s e a s o n s .

" 9

Pa

B

~ t j

+ ~

P~

q

u

0

r

c'4

Biometry of B o m b a x c e i b a Flo+c,ers

cr ~ ~ cr'+'I ~

c o

B~

r ~

~ o

t,,.,..

c ~

+++.,+

- ~" -+ 0+ I I c-I

.0 ~ o+ +. ~ ] t

"+ ~ '~ +" I I [

gi ~ +, ~o - - ]

"- § ~ + - . . . . i I

~ ~ ~ ~ ~ I

-~ I I

M

C'I

L~.

C L~

L~

U";.

++r~,

Lr"

0

I

ze+~ B ~

i .~ +u

1,0 +,

! i +'~ ~

,'+ +U

T. A. DAvis 313

d l o w e r s in w h i c h all f ive b u n d l e s b o r e t h e s a m e n u m b e r of s t a m e n s were s e p a r a t e d ou t .

Also, those f lowers w i t h fore" b u n d l e s b e a r i n g t h e s a m e n u m b e r s a n d t he f i f th a d i f f e r e n t

n u m b e r w e r e a c c o u n t e d for s e p a r a t e l y . T h e r e a re f ive m o r e poss ib le s i t u a t i o n s as

seen in T a b l e 12, a n d t he f lowers a r e g r o u p e d a c c o r d i n g l y . T h e 24 t rees a r e a lso

a r r a n g e d a c c o r d i n g to t h e a s c e n d i n g o r d e r of t h e i r s t a m e n s p e r f lower. I t m a y b e

seen t h a t in a b o u t 30 p e r c en t of f lowers , a l l t he p e r i p h e r a l b u n d l e s b o r e t h e s a m e

n u m b e r of" s t a m e n s . O n l y 3 f lowers o u t o f 1200 h a d all d i s s i m i l a r p e r i p h e r a l b u n d l e s .

F lowers w i t h f o u r s i m i I a r a n d o n e d i f f e r e n t b u n d l e s a r e a l m o s t as f r e q u e n t as the firsL

ca tegory . A p e r u s a l o f the T a b l e wil l s ugges t t h a t f lowers w i t h s m a l t e r n u m b e r s o f

s t a m e n s h a v e a t e n d e n c y to possess b u n d l e s o f t he first two ca tegor ies . T r e e I0 is a n

e x c e p t i o n . A n o t h e r s t r i k i n g p e c u l i a r i t y o b s e r v a b l e f i o m the d a t a is t h a t t rees 18 a n d

24 h a v e t h e l eas t n u m b e r of f lowers u n d e r t he first two ca tegor ies . I t m a y b e r e c a l l e d

t h a t t he se a r e t h e two t rees w h i c h p r o d u c e d t he m a x i m u m n u m b e r of d o u b l e s t a m e n s

(v ide T a b l e 6). T h i s suggests t h a t t he p r o d u c t i o n of d o u b l e s t a m e n s is c o r r e l a t e d w i t h

a n u n s t a b l e n u m b e r o f s t a m e n s p e r b u n d l e .

T a b l e 13. B o m b a x ce iba : Flozoers at weekly intervals according to nature of peripheral stamina! bundles

Trees Nature of bundles Weekly intervals

1 2 3 4 5 6 7 Total

Percent- age of total

5 alike 14 22 17 8 18 22 14 115 33"72

4 same 1 different 15 12 11 14. 16 15 14 97 28'45

3 same 2 different 8 6 13 17 6 4 2 56 16"42

3 3 FI ,L1 7 5 4- 9 4 5 4" 38 11'14

2 q- 2 -b I 6 5 5 '2 5 4 5 32 9"38

'2q- 1 + I-1- 1 . . . . . . . . 1 . . I 2 0"59

5 dissimilar . . . . . . . . . . . . 1 I ~ 0'29

Total 50 50 50 50 50 50 ,11 34l

5 alike 15 6 10 8 18 2t 78 26'00

4 same 1 diffc,'ent 10 18 22 14. 15 15 94 31'33

3 ,~ame '2 different 12 l0 9 14 ~; 6 57 t9-00

3 b 1 "- I 9 I0 0 3 6 5 39 t3.0[)

2 q-2 + I 2 5 '2 8 [5 1 ~ 23 7.67

2-{. I q- 1-F 1 '2 1 1 '2 . . '2 8 2.67

5 dissimilar . . . . . . t . . . . ! 0'33

T,,tal 50 50 50 50 50 50 300

314 ~r of Bombax ceiba Flowers

T a b l e 13 (Col~,td.)

Trees Natttre of but~tdes Weekly intervals

1 2 3 4 5 6 7 Total

~r age of total

I0

5 atlke .l.l 28 34 22 24 7 156

4 same 1 d i f f cma 7 15 [ l 15 19 2 69

3 same 2 difl'ercia~ ! 4. 2 5 4 . . 16

3+ I + 1 1 2 1 4 l I l0

2 -I- 2 -" 1 . . I 2 4 l . . 13

2 + 1 + 1 q- 1 . . . . . . . . I . . l

5 dissimilar . . . . . . . . . . . . . .

~50.00

26-54

6-15

3.85

3.08

/J-38

TotN 50 50 50 50 50 10 260

'13

5 alike 19 12 17 10 14 8 80 29.63

4 same 1 dift~re~.t 15 20 16 18 15 6 90 33.33

3 same 2 differen: 13 7 9 9 I0 2 45 16.67

3-1- 1 -[- 1 7 4 3 8 8 2 32 I 1.85

2 + 2 + 1 1 7 4 4 3 2 21 7.78

2 + 1 + t + { . . . . 1 1 . . . . 2 0'74 -

5 dissimilar . . . . . . . . . . . . . . . .

Total 50 50 50 50 50 20 270

i8

5 alike 2 2 3 3 4 l 15 5.70

4 same i differcm 9 9 9 I5 9 3 54 20"53

3 same 2 differen~ 6 6 8 5 9 2 30 13.69

3 + I + l 12 14 13 10 15 2 66 25.10

2-I-2+ 1 12 7 7 I0 10 4 50 19.01

2 + l + I - I 9 II 9 7 3 . . 39 14-83

5 dissimiiar . . I I . . . . 1 3 1.i4

Total 50 50 50 50 50 13 263

T a b l e 13 s h o w s f u r t h e r d a t a o n th is p h e n o m e n o n . A s a m p l e o f 5 t r e e s ( o u t o f 24)

w a s s e l e c t e d a n d t h e n a t u r e o f t h e p e r i p h e r a l b u n d l e s r e c o r d e d a t w e e k i 7 i l~tervals .

O v e r 250 f l o w e r s f i ' om e a c h t ree w e r e e x a m i n e d d u r i n g six o r s e v e n w e e k s . T h e f i gu re s

f o r t h e f i rs t w e e k a r e t he s a m e as in T a b l e 12 a n d t h e d a t a o f T a b l e 13 h e l p to c o m p a r e

t h e b u n d l e s d u r i n g s u b s , : q u e n t w e e k s . I n t r ee s 9, i 0 a n d 13, t h e b u n d l e s b c c a i n e m o r e

d i s s i m i l a r w i t h t i m e . T r e e 18 m a i n t a i n e d a l m o s t t h e s a m e c o n d i t i o n t h r o u g h o t ~ t ,

a n d in t r ee 3, f l o w e r s w i t h s i m i l a r b u n d l e s i n c r e a s e d w i t h t i m e w i t h a r e w - r s a I duri1~g

t h e f o u r t h w e e k . Tree.~ 9, l 0 a n d 13 m a y b e r e g a r d e d as d e m o n s t r a t i n g t ~ t i g u e - e f l E c t .

T. A. DAvis 3 1 5

C3

t l

III

X |

X

X

X

tli

11o x X

• f i x

I t

t t •

X l l X

•

1t0

X • X

I I

X

X X

X

X X

X

1 • I • % O~

Q) r

'.31G Biometry of Bombax ceiba Flowers

VARIATION IN THE ('~,ENTRAL BUNDLE

' l /hough the centrai bundle of s tamens in l~ombax cdba is general ly a cons tan t possessing

!5 stamens, three trees showed striking variat ions. Trees i8 and 22 bore ex t ra

:-,LzLmens in some flowers while tree 23 had less than the usual n u m b e r . T h e in-

,.:~case in the number of s tamens is b rought abou t ci~.her by the d u p l i c a t i o n of the

~t,,~rter stamens or by the spl i t t ing of one or more of the 5 innermosL stamens. S t ray

c:~.,es of variatiotl in the central bundie were encountered in six o the r trees which mus t

I)c ~'egarded as freaks. In tree 18, one flower had ]css than 15, t h o u g h m a n y had

c:.:cess stamens. Tree 23 showed the reverse si tuation. In flowers where the cent ra l

b ,mdles show a reduct ion in number , the per iphera l bundles also show a co r r e spond ing

dil lkrence. But there is no indica t ion that the per iphera l bundles show a co r r e spond ing

,:{ii:~'erence wheye the centra l bundles had grea ter numbms.

VAR.IANCES AND ~'V]~EANS OF 58 .[*REES

['he variances and means of s tamens pe," tree for die 34 trees f rom where flower

~>'_~:ptes were drawn only once (vide Tab le 5) are represented in Fig. 4 by crosses.

q h e dots represent those for the 24 t,-ees f rom where flowers were s tud ied at weekly

itm:rvals. O f the 58 trees, a l l bu t 9 have means betweml 62 and 80 and var iances

be,we&t 0"3 and [5"88, that is s t anda rd devia t ions between 0.55 alad 3.99. Two

c:.:,:eptions have high means, six high var iances a a d ,:,lie has both. F r o m the figure,

iu is ctear that a much higher percentage of trees where flowers were s a m p l e d at weekly

itttcrvals show high figures for var iance c o m p a r e d to the rest of the trees. T h i s i s

because in most trees the mean s tamen numbers changect (decreased in most cases) wi th

~ime. The re is no obvious corre la t ion be tween mea~.s and var iances .

Fig. 5. A peripheral staminal bundle of B. ceiba bearing two sterile stamens.

STERILITY IN ANDROEGIU~.~

Of the 58 trees examined, two trecs exhibi ted par t ia l sterility of tim stamens. Ster i l i ty

ira these trees is manifested by the produc t ion of s tamens devoid of an the r s or evela fully

T. A. DAvis 317

developed filaments. They are r educed to s taminodes abou t ha l f the n~,rn-ial size.

Fig. 5 shows a per iphera l bundie with 2 sterile stamens. Each per iphera l it p roduce

fertile an thers (Davis and M a r i a m m a , 1965). One of these trees (number "1, unfor-

tunate ly des t royed towards the end of I963) p roduced 55.2 per cent of the ft~,~vers with

one or more sterile stamenS. 138 flowers bore 376 sterile stamens, that i- 2.72 per flower (or 1-50 per flower wEen all flowers sampled are taken into account) . T h o u g h

flowers wi th sterile s tamens are p roduced throughout the flowering seacoast, weekly

e x a m i n a t i o a showed tha t the fi-equency of abno rma l flowers s teadily decrc,:sed with

t ime as seen below.

Period of bloom Flowers Perceiztage of examined flowers with

sterile slame~is

Firs t week 50 84-00

Second week 100 63.00

T h i r d week 50 44-00

Four th week 50 22.00

Tota I 250 55.20

The m e a n s tamen number ( inc luding sterile ones) per flower of this tre,: is 81.87

and t imt for ~-~lowers showing one or more sterile s tamens is 82"14. This di!i , :rence is

not s tat is t ical ly significant. But ano the r tree (16) shows a different situati,.:~ . ( )n ly

12 out of 191 flowers sampled bore steri le stamens. Except for one Ilowev .,,,,ith two

sterile s tamens, the rest had only one each. The mean n m n b e r of s tamens !wr flower

with steri le s tamens is 80.50, and that for the rest 76'12 (o," for all flowers 76-3!~ . Here

the difference is s tat is t ical ly significant, and even if the sterile s tamens ar~ ignored,

the r e m a i n i n g no rma l stamens in these flowers are significantly more .tha~ in those

wi thout steri le stamens.

in these two trees, flowers with sterile s tamens are quite common and only :he peri-

phera l s tamens are reduced to s taminodes. But there is ano ther stray case of :, ce~tral

shavt s t amen reducing to a s taminode in tree 18.

I~NTuMBER OF STAMENS PER PERIPHERAL ~UNDLE

In Fi~. 6 the n u m b e r of pe r iphera l bundles is p lo t ted against the numlmr o~ - tamens

per bund le for 24 trees. Bundles with as few as six and as m a n y as 31 stamc;~s were

also recorded . T h e mode is I2, the next l ' requent n u m b e r being 10. I t is ~:!:o c lear

f iom thi~ figure tha t bundles with even numbers of s tamens m'e c o m m n n e r tlt~: n those

wilh odd numbers . T h e odd nulnbers arise out of fur ther dupl ica t ion of a s t a tu re , w f iom

a stamm~ not hav ing the p r imary lbrldng. As stated ea, 'lier, the s tamens in a I>': ipheral

318 Biometry of Bombax ceiba Flowers

4o" ---4/

9X J,2"

8A'I,.'

7 x I J "

~'X t J, %

4xlE-" - -

3xtO - !

2X~O ~

DtSTfPIDI/T/ON' OF Sr.4b, IE~,'S / OUNI3I. E

L/IN 5 pEf?IPt-IE:PAL ~UHDLES'j ~

'~ i t i

200

*9 8 JO t2 r t 8 ~8 20 2f 50 j : t

SYAMEN$ PER [3UNDLE

Fig. 6. Number ofperlpheral stamina! bundles against number of stamens per bundle.

bundle appear in pairs, suggesting that a normal stamen splits into two, each bearing

a single-celled anther. Thus, presuming that a bundle originally had 5, 6 or 7 stamens, when they all forked each into two, the bundles would have an even number of stamens. This phenomenon called chorisis was explained in detail by

Velenovsky (1910).

T. A. DAvis 319

~k

ua 0.

r ~S

ta

~a

320 Biometry of Bombax ceiba Flowers

C~

C~

�9

~q

L~

C~

I i 1

- I I

- I I I I I I ~ -

- ~ ~ , ~ ~ ~ ~ § I ~-

T . A . D a v i s 3 2 1

. . . . i ] i - ~

I I I I I -

i ~

co '~

c - !

N

N 2

N -

@ q

".;4 "~

~,2"1

322 Biome#y of Bombax ceiba Flowers

A somewhat similar condit ion may be seen in Fig. 7 which represents the n u m b e r of

flowers according to total n u m b e r of stamens pet" flower. The most obvious difference

one can see is that flowers with odd numbers of stamens are c o m m o n e r than their

even numbered neighbours. This apparent reversal is due to the centraI bundle which

has usually 15 stamens. Thus, under each column, if 15 stamens are subtracted, it

will be seen that flowers with even numbers of stamens have greater frequencies. The

two principal modes in this figure are at 75 and 65, and if the 15 stamens of the central

bundle are excluded, they wilI be at 60 and 50 stamens per flower. Hence, one peri-

pheral bundle will bear one-fifth of these numbers , i.e. 12 and 10, which are the modes

of Fig. 6. The distr ibution of 5328 flowers of 24 trees according to n u m b e r of stamens

per flower is seen in Tab le 14.

Tab)e 15. Bombax ceiba: Seeds per capsule and stame1~s per flower

Trees Capsules Seeds/capsule Stamens] Length of Wt. of tested good sterile total flower capsule 1000 seeds

(mm.) (gm.)

A 8 94-38 .. 94.38 71.18 70.00 33.22*

B 49 94.24 34.06 128.31 .. 71.29 15.27

13 35 137.66 0-71 [ 38-37 73.77 91.57 26.20

1 50 136.78 7 .58 144.36 ~55.97 93.70. 28.75

24 48 160.85 0.67 161.52 99.19 85.23 30.03

3 4.0 134-63 28.48 163-10 67.28 89-60 18.65

9 45 133.69 38-I8 171.87 71.89 66.87 21.23

11 45 175.53 0.38 175.91 72.5g 99.47 39-62

18 50 t88.42 2.96 I91-38 77-95 9I .52 27-54

19 I5 190.93 16.53 207.47 78.97 I08-27 24.95

10 10 332.60 6.90 339.50 71.90 95.30 32-86

*Based on the weight of 500 seeds.

NUMBER OF SEEDS PER CAPSULE

Capsules not exceeding fifty per tree were opened and their total seeds ( including

underdeveloped ones) counted for 11 trees of which 9 are from the list of 24 trees

(Table 6) whose s tamen numbers are aIso known. The n u m b e r of seeds per capsule

varied f iom 94-38 to 339.50 between trees (Table 15). The var iance a m o n g capsules

of the same tree is also quite high. Some trees produce sterile seeds in appreciable

n u m b e r s - - o n e has just above 20 per cent while two others produce abou t 30 and 35

per cent. One tree has no sterile seed while four others produce less t han 2 per cent

underdeveloped seeds.

T. A. Daws 3_a

There is some indication that the immber of seeds per capsuIe between trees vm-ies

with the size of capsule; the number varying with the size of the capsule within a tree

is vividly demonstrated in many trees. The size and shape of capsules varies appreci- ably between trees, and so does the weight of seeds. The shape of seeds and the seed coat colour also vary between trees. Tree 10 appears to be very different fl:om the

rest by possessing the maximum number of seeds per capsule and rectangular b,'own

seeds. I t may be mentioned that this is the only tree producing pale orange cotoured

flowers. The weight of seeds also varies significantIy with trees. There is no

indication that seeds fi'om capsules producing smaller number ot" seeds weigh more. There is also no correlation between the size ofa capsuIe and the weight of seeds.

DISCUSSION

The mean stamen number in Bombax ceiba varies significantly with individual trees, and this 's tandard' number for a tree does not vary appreciably between branches of

the same tree and during different periods of the same blooming season or between

seasons. Also this number does not fluctuate with the varying intensities of flowering

during different years. But trees standing very close to each other can differ greatly

in their mean stamen numbers. The foregoing information suggests that the variabi-

lity in stamen number in this species is genetically controlled which means that indi- vidual trees differ from one another in the degree to which the development of the

flowers is canalised (Waddington, 1942, 1957). In 1962 when I sent data on only

three trees (trees 1, 3 and 1.8 of Table 6) to Professor C. H. Waddington, F.R.S., he

informed me that though the data provided good evidence to demonstrate canalisa-

tion of development in 13ombax ceiba, a sample of only three trees was rather small, and he suggested that it would be valuable if I could sample some more individuals, or

still better to do the genetics of these trees in detail to produce evidence that the varia-

tion is genetic. But as the latter project will take 6-8 years, this aspect has been given

up. Instead, more samples from different populations involving over half a million

stamens were collected to see how far they differ genetically f'rom the cartier popula-

tion. After scrutinizing the fi-esh data given in Tables 5 & 6, Professor Waddington

made the following comments: ' In ttle wider sample you have now made, t notice

that there is also some difference in variance between the different individuals, but that

is not so large as it was in the original small sample. I am not quite clear what con-

clusions can be drawn fi'om your data. They certainly show that there is some

difference in canalisation between different trees, but there is, of course, no way of

telling whether this is a genetic property since no breeding experiments have been

done'. I give some further variation among trees which may or may nc~t be

due to genetic differences. Tree 10 has very pale orange flowers which separates

this tree fl'om the rest that bear deep crimson flowers. This is further unique in that the nurnber of seeds per capsule (339-50) is over 63 percent in excess of the next largesl

seed-bearer. Its seed coat is brown (seeds of most others are black) and the seed is

rather rectangular. Another tree is distinct by producing unusually large number

324 .Biomet~y o j" Bombax ceiba Fb.~wers

of sterile stamens. A further tree produces petaloid ~tamens. *~ret another tree

produces fruits which are peculiarly dumb-bell shaped. A seedling growing under tree 1 (suspected to be the mother) commenced flowering in 1965 with 23 flowers.

The stamens in aIl the flowers were counted and compared with those of the probable

mother.

Sl(,'met~ j:er f/aHat~ce ~:\'o. of

Moth,er 65.60 9.71 1 t,8 Pro2eT~y 65'2 i 1" 14 23

Inspire of din conspicuous difference in the age of tl-c parent and progeny, the

number of stamens per flower they bear is almost the rome. F r o m d a t a given in

Tables 5 and '6 it will appear tha t the number of stamcn~ per flower and the age of

the plant are not correlated. However, one of the tr,'es in Tab le 9 registered a

progressive increase in the number of stamens dur ing five years. I n anot;her centre, two young plants were located growing very close to each other

near a house- The flowers of these trees looked atike i~ size as well as the lighter

shade of the petals. 25 flowers f'rom each tree were sampled and their stamens coun-

ted. The mean stamen numbers did not differ significan/ly as seenbelow.

,57mne~sf']lower :.,ariance

Pla~zt 1 64-72 I8"31 Plm~t 2 64.'04 10-44

The late Professor J. B. S. Haldane, F.R.S. considered Bombax ceiba to be a nice example to demonstrate the variability of canalisation, and ideal mater ia l on which

to study normalising selection. A somewhat similar phenomenon was observed in Euca!,.'plu.s globulus by Davidheiser

(1965). The capsules of this species have usually four or five carpels, and those with three or six are rare. The more capsules a t,'ee produces of either of the extreme

types, three or six, the !ess it tends to produce of the otlmr. The ratio of the fours

and fives is also correspondingly shifted. Although this trend appears to be common

to all the trees, the trees do not fall into a single series. Each tree appears to have a

different ratio. There was no evidence to indicate that the ratios are different on

different branches of the same tree. Four trees standi~ag very close to each othm gave capsules with different ratios. Davidheiser concludes that the ratios nf carpeli

per capsule in Eucalyptzt.s globzdus are dependent upon a number of genetic factors. In a majority of Bombax ceiba plants sampled, the number- of stamens per flower

dropped, though not significantly, with time. The peak blooming for a tree is durilag

the second week, or for some trees between the second and third weeks. Thus, it may appear that there is a negative correlation between the n u m b e r of s tamens (per

flower) and the intensity o~'[tower production. However, ti~e two trees p roduc ing sterile

T. A. DAws 325

stamens behaved differemlv since the percentages of flowers in them bearing stcrile stamens and the ~aumbel ,_,f sterile stamens per flower diminished with time. In Hibiscus rosasincnsis, the m~mber of stamens per flower was found to vary significantly with time and the mean per flower increased as the flower production decreased (Davis and Ghoshal, 19(;5). During monsoon (June-October) , flower production

was at its maximum. BL~ ~.he mean stamen number per flower was higher during the

rest of the year. The right and leR-ham!cd twisting of the corolla is also observed in a few families

other than the Bombaca,:cae. All the 34 species of the Malvaceae and 14. of the Bomhacaceae observed s!~owed this floral asymmetry without an exception. Also a few species of the Lin::ceae, Caricaeeae, Plumbaginaceae and Cochlospermaceae

examined behaved in a like manner. However, in Euphorbiaceae, Sterculiaceae and others, some species showc d this floral asymmetry while in others the petals are either

valvate or imbricate. In a few palm species, the inner whorl of perianths representing the petals show regular t~isting (both directions) as well as imbrications within the same tree (Davis, 1964b; Davis and Kundu, 1966).

The left-handed flowers i,~ alt the trees of Bombax ceiba investigated were significantly in excess of their counterp:Lrt although the proportion did not change with time durillg the blooming period. Among Malvaceous species, Hibiscus rosasinensis and Abutilon indicum produced significm:dy more left-handed flowers (Davis and Selvaraj, 1964). With regard to the foliar ~:s>mmetry in Cocos m:cifera, while the data from the Northern hemisphere showed an e~cess of left-handers, the right-handers were in excess in the Southern hemisphere (Da\is, 1964b). The North-South hemispherical difference was statistically significan~ at the 5~ level. Since the foliar asymmetry in the coconut is not genetically determi~ed (Davis, 1962), one might attribute some physical cause for this. Dr. Grotc Ikeb~ : of Tasmania, on the basis of available data, was inclined to believe that foliar asymmetry was influenced slightly by the earth's magnetic field. Since the data o~ /:ombax ceiba and the two Malvaceous species showing a significant excess of leR-i::,nders are fi'om the Northern hemisphere (mostly l iom Calcutta), it may be presu~,~cd that some physical force more favourable for left-handed- ness is operating in this i,~_qaisphere. IL may be mentioned that Kundu and Sarma (1966) observed a slight e::c~ss of left-handed Corchorus capsularis plants in a population of 16,408 at the Jute Agri,:ultural Research Institute, Barrackpore near C, alcutta. In an earlier experiment al ille same centre reported by Sarma (1965), 54..31% of C. ca]:sularis improved str~i~: JRC,-212 were left-handed.

No regularity in the pr,,duction of left- and right-handed flowers in the ultimate units (fascicles) of the infi,.~~:sccnce could be observed in Bombax ceiba. From Eichler's (1878, Fig. 115A, p. 284) diagram of the section of an inflorescence of Matva sy[vestris having three flowers, it m.:~ appear that a right-hander is alternated by a lei't-hander which in t u r n is followed l~>, another right-hander. To verify this, flowers flom several shoots of Hibiscus cam:abim,.', H. sabdari..ffa, H. csculenl~.~m, lJ. rosasincnsis and Ceiba pentandra (Davis and Kundu, 1965~ were examined. No doubt, some shoots of these species bore the two types of fl

326 .Biome#y of Bombax ceiba Flowers

axils. Bm analysis of the data from large numbers of shoots in difl'erent species did not at all suggest that the flowers are arranged in some regular o~-der. However, in a variety of Althav'a rosea, a slightly different situation was met with. Almost every leaf axil in this plant bore two flowers (once the flowering started~, the first and the axillary (main) one being a right-hander. The second flower, an extra axillary one located always towards the right side of the axillary flower was a ieft-hander. Thus in this variety ahnost all the axillary flowers (first flower in each leaf axil) were alike in their petal-arrangement. However, other 'varieties' ofAlthaea ro~.,a behaved like the rest of the Malvaceous species.

SUMMARY

Tile coro!la of Bombax ceiba, typical of the Bombacaceae, is cont,-,rted, all petals in a t'lower twistiI~g clockwise or counter-clockwise. Tile two kinds of [towers are almost equally common in any plant and even on a large flowering shoot. The entire flowers produced in three tt:ees during the 1962 season were examined, :.rod 51.37 per cent

of them (out of 33,689 flowers) were found to be left-handers. I 'he percentage of left-handers (or right-handers) did not change signifieantIy with time during the blooming period. No significant difference in the number of stamens between the two types ,.,f flowers was noticed. So also the weight of the capsule developed fl'om

one type of flower and the number of seeds per capsule did not differ appreciably from

those of their counterpart. A study of the internal structure of the flowers at various stages of development

suggested that the petal-stamen cord even at a very early stage m:mifests asymmetry, and the distribution and deveIopment of the petaI-primordia in the r_wo types of flowers

are reversed. A flower of Bombax ceiba has five staminal bundles arranged izl a ring which are

united at the base and applicated to the lower end of the corolla. Each bundle has pluriseriate stamens whose number varies fl'om 6 to 31. Enclosed by the flve bundIes and surrounding the style is another bundle, the central verticil, bearing invariably 15 stamens of which the longer five have two anthers each. The short ten stamens of

the central verticil and the peripheral stamens bear only one anther each. The mean stamen number varies slightly between flowers of the same tree and

significantly between trees, and this is mostly due to the variation in the periphera[

stamens. Of the 58 trees from which flower sampIes were examined (involving over hai l a million stamens), the mean per tree varied from 62"75 to 102.00. In many trees the number of stamens dropped sligEtly with time. Flowers on different shoots

of a tree b,)re the same number of stamens. No significant difference was noticed in

the number of stamens per flower in a tree during different seasotts. Also the mean stamen number did not vary with the variation in the intensity of flower production

in a tree dtwing different seasons. Sterility of stamens was noticed conspicuously only in two of ~he 58 trees. The

percentage of flowers bearing sterile stamens and the number of ~terile stamens per

T. A. DAVIS 327

f lower d i m i n i s h e d w i t h t i m e d u r i n g a b l o o m i n g season. T h e n u m b e r of seeds pet"

capsuIe , e s t i m a t e d tb r I 1 t rees, was f o u n d to v a r y s ign i f i can t ly b e t w e e n trees.

AGKNOWLEDGEMENT

I t was t h e l a t e P ro fesso r J . B. S. H a l d a n e , F . R . S . , w h o i n d u c e d m e to look i n t o the

v a r i a t i o n in t h e s t a m e n n u m b e r s of Bombax ceiba. I wish to r e c o r d m y p r o f o u n d

g r a t i t u d e for t h e u n f l i n c M n g he lp he r e n d e r e d m e for o v e r seven yea r s of m y as soc ia t ion

w i t h h i m . i t h a n k Miss K. O. M a r i a m m a for the a n a t o m i c a l p r e p a r a t i o n s ,

Sh r i S. K . D e for t he d r a w i n g s , a n d m y wife for the he lp in c o u n t i n g t he s t a m e n s .

REFERENCES

BAKHUIZI-N VAN DEN BRINK, R. C. [19241. Revisio Bombacacearum. Bull. Jard. Bat. Buiten-., Ser. 3-6, 161-240.

C~'.AT'r~Nv.E , D. AND R.~.IZADA, M. B. (19501. Correct name of Indian silk cotton tree (Semat). Ind. For., 76, 154-155.

CJ-LaT'rERJEE, D- AND RA:ZADa, M. B. (19541- Note on the typification of the generic name Bombax L. Taxon, 3, 102.

DAVIBIIEISER, B. (1965). Eucalyptus fruit. Turtox News, 43, 66-67. DAvis, T. A. (i9621. The non-inheritance of asymmetry in Cbc0s nucifera. J. Goner., 58, 42-50. Davis, T. A. (1964a). Aestivation in Malvaceae. .u 201, 515-516. DAVIS, T. A. (1964.b). Possible geo-physieal influence on asymmetry in coconut and other plants. Procd.

FAO Working Part.), on Coconut, Colombo, 2, 59-69. DAxqS, T. A. A.'-;D GI-mSHAB, K. K. (19651. Variation in thc floral organs o[" Hibiscus rosaJinel~sis L. J.

Ind. Bat. Sac., 44. DAvis, T. A. AND KUNDV, A. (19651. Floral structure and stamens in Ceiba pentantha (L.) Gacrtn. J .

Bombay .Nat. Hist. ,S'oc., 62, 394-41t. Davis, T. A. AND KUIXDU, A. (19661. Aestivation t~fperianths of Areca catcchtl Linn. fi'uits. J. Bombay jVat.

Hist. Sac., 63. DAVIS, T. A. AND MARIA~.~.~,~A, K. O. (19651. The three kinds of stamens in Bombax ceiha L. Bull. Jardin

Botanique de PEtal, Bruxelles, 35, 185-211. Davis, T. A. ,',tad SELVAR:XJ, C. (I9641. iVIoral asymmetri,' i2J MMvaeeae. J. Ban,be 9, .,Vat. Hisl. Soc.,

61, 4-02-409. DUGA,~ID, A. (i9451. Rcvalidacion dc Bombax ceiba L., coIno especie tipica del gene,'o Bombax L. y deserip-

clan de Pseudobambax germ. nov. Caldasia, 2, 47-68. Eiciit.~r% A. W. (I878). Blitthendiagramme, II. Leipzig. IVuICrADO, C. X. (19391. Ti~e typilication of Bombax, Gassam/,itms and Salmalia. Ga~d. Bull.; Straits Settl.,

10~ 173-18I. GlaeEN, M. L. (19291. Proposals by British Botanists, Ii~tcraational Botanical (_:engross, Cambridge

(Ei~gland), 1930. Nomeuclature, I55-195. HooK~mJ. D. (I8721. Flora ofBdti.*h hMia. I. L. Reave a ,d C-: London. K.UNDU, B. (3. AND .%~.P,M.X, N'|. S. (19661. Direction -fl,:af spiral~ in Corchorus capsula~is L. (Under

publicati.n). L,'~wl~et~

328 Biomchy oJ" Bombax ceiba Flower~

Roy, S. K. (1963). The variation o1" organs of indivldtl:d plants. J. Genet., 58, 147-176. S..'iLIm ALI (1932). Flower-birds and bird fl~Jwers ia incest, j . Bombay N~,t. Hist. 5be., 35, 573-605. S.~,RMA, M. S. (1965). A prelimiliary ~tudy ol~ the direction of leaf spiral and phyllotaxy in jute.

J. Ge,et., 59, 140-143. SCHU,',L~,NN, K. (i886). Aestivation der Bluten and ihrc mechanlsel~.en Ursachen. Ber. d. deutsch, bolan.

Ges. 4, 65. V~.ENOVSK'~', .J. (1910). Ke~leichc, de Mv~]d~ologie dcr Pf:,zen. Verlags-l~uchhandlul~g yon Ft. Rivnac:

Prag. WADDING'rON, C. g . (1942). Cailatization of dev,qopn~,:tat and the inhe,'itance of acquired characters.

N(,ture, 150, 563-565. WaDDIN~ZTON, C. H. (1957). Ttw ~tmtegyoflhegenes. (_;.:,,rge Al!en and Unwin Ltd: London.

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