8/7/2019 62===Biosystematics of the NZ Pterydophytes===

1/5

New Zealand Journal of Botany, 1985, Vol. 23: 681-6850028-82 5X/85/23 04-0681 $2.50/0 Crown copyright 1985 681

Biosystematics of the cryptogamic f loraof New Zealand: PteridophytesP. J. BROWNSEYNational Museum of New ZealandPrivate Bag, Wellington, New Zealand

Abstract With 189 native and 22 adventivespecies, pteridophytes are a numerically small buteconomically and ecologically important compo-nent of the New Zealand flora. Taxonomically theyare well known but, following several major revi-sions and many nomenclatural changes in the last20 years, there is a need for a new Flora treatmen t.A more expansive style of Flora including a greaterrange of information and illustrations for bothnative and adventive taxa is contemplated. Theevidence for hybridisation amongst New Zealandferns is outlined and a comparison with Cockayne& Allan's list suggests that its extent m ay be greaterthan they suspected. Most fern hybrids, with thenotable exception of those in Blechnum, appear tobe effectively sterile. Chromosome counts have beenobtain ed for abo ut 75% of nativ e species of which54% are polyploid, a figure comparable with othertemperate floras, but only 2% are apomictic.Chemotaxonomy of New Zealand ferns is still inits infancy but can be expected to provide realassistance in subdividing some large families offerns, especially if combined with morphologicaland cytological analysis. New Zealand pteridologyis now at the point where purely taxonomicinvestigations are likely to give way gradually tothe study of more complex biosystematic problems.Keywords apom ixis; biosystematics; chem otax-onomy; chromosome numbers; cytology; ferns;Flora treatment; hybridism; New Zealand; pteri-dophytes; taxonomy

INTRODUCTIONIn terms of species, pteridophytes are one of thesmallest groups within the New Zealand flora, butthis belies their im portance in two regards. Firstly,

Received 15 March 1985

a disproportionate number, notably Salviniamolesta, Pteridium esculentum, Paesia scaberulaand (potentially) Equisetum arvense, are of majoreconomic relevance as serious weeds of waterwaysand agricultural land. Secondly, they form a sig-nificant component of forest vegetation occurringas trees, lianes, epiphytes, and ground-growingforms, the latter largely replacing the floweringherbsof northern hemisphere temperate woodlands. Theirsheer abundance in areas of high rainfall, and theirobvious aesthetic appeal both in the wild and incultivation, have given New Zealand ferns aninternational reputation that is reflected in theirpopularity in botanic gardens and in the amountof research that has been done on them. There isevery indication that public interest in and scien-tific study of ferns will continue to develop in tan-dem to their mutual benefit.TAXONOMYBrownsey (1983b) provided a brief historical reviewof fern taxonom y in New Zealand and showed tha tfollowing the rapid expansion of knowledge in the19th century there was a period of slow progressuntil the publication of Allan's "Flora of NewZeala nd" in 1961. This stimulated the preparationof a series of taxonom ic papers that h ave led to theferns now being very well known probably bet-ter than any other section of the flora. Revisionsof many critical genera, including, in order of pub-lication, Lastreopsis, i.e., Ctenitis of Allan plusRumohra hispida (Tindale 1965), Doodia (Parris1972), Tmesipteris (Chinnock 1975), Grammitis(Parris & Given 1976), Lindsaea (Kramer & Tin-dale 1976), Asplenium (Brownsey 1977a,b), Botry-chium (Braggins 1980), Hypolepis (Brownsey &Chinnock 1984), and Deparia (Kato 1984) havebeen completed, with work on Pteris and the"capense" section of Blechnum in progress. Themajor groups still requiring attention are Lycopo-dium and Hymenophyllaceae, but, in large part,these taxa present problems on a world-wide basiswhich are unlikely to be resolved by New Zealandbotanists working in isolation.These revisions and other nomenclatural changes,together with the general reappraisal of family andgeneric limits within the Pteridophyta that is cur-rently being undertaken by fern taxonomists

8/7/2019 62===Biosystematics of the NZ Pterydophytes===

2/5

682 New Zealand Journal of Botany, 1985, Vol. 23Table 1 Numbers of native and adventive fern speciesin New Zealand (data from Brownsey et al. 1985).

SpeciesTotal Endemic

SubspeciesTotal Endemic

Native 189* 89(47%)Adventive 22tTotal 211

6t 3 (50%)

* Includes 8 un-named, t includes 1 un-named.

throughout the world, mean that Allan's (1961)Flora is now irritatingly out of date. Up to 40% ofthe currently accepted native pteridophytes areeither not listed by Allan or are incorrectly or inap-propriately named according to modern concepts.A smaller proportion (c. 25%) are either not listed,or are poorly denned. These inadequacies, com-bined with the absence of all the adventive species,mean that A llan's treatment of the ferns has becomevery unsatisfactory, particularly so for those who,for whatever reason, have been unable to keep upwith subsequent developments.Brownsey et al.(1985) have recently com pleted acomprehensive review of pteridophyte taxonomyin New Zealand in which they provide a checklistof accepted species, a complete list of synonyms,and an outline of our current knowledge togetherwith those areas requiring further study. The essen-tial statistics of the flora from this checklist aregiven in Table 1. The full extent of nomenclaturalredundancy is revealed by the fact that for the 211accepted species in the flora, Brownsey et al. (1985)list almost 1200 names (including over 550 bas-ionyms) which have been used in relation to NewZealand pteridophytes!Whilst this review provides a nomenclaturalreference point in a group whose names are chang-ing with confusing rapidity, the longer term needis for a new Flora trea tmen t. Although it may seempremature to suggest another round of Floras whenthe present series begun by Allan remains to becompleted, there is ample evidence from Univer-sity and G overnm ent de partmen ts, students, school-teachers, amateur botanists, and other interestedmembers of the community to indicate that a newfern Flora would be of wide professional and pub-lic interest. Fu rtherm ore, th e ferns are relatively fewin number, they are well-studied, and there arepeople available in New Zealand to write such aFlora which, I believe, could set some welcomeprecedents for subsequent vo lumes on other groups.In addition to the essential names, descriptions,keys, and updated details of type material, onewould certainly want to see included illustrations,

chromosome numbers, distribution maps, fullerecological information, and floristic comparisonswith related geographical areas such as Australiaand the other Pacific islands. Reference to chemo-taxonomic studies would also be desirable. In otherwords, a more expansive and complete style ofFlora, incorporating both native and adventive taxa,is contemplated.

HYBRIDISMCockayne & Allan (1934) listed 491 groups of wildhybrids in the New Z ealand flora, of which 41 wereferns. No attempt has ever been made to reassessthe accuracy of the list of fern hybrids, and indeedsuch a task would be rather difficult in the light ofthe many taxonomic revisions which have beenundertaken subsequently. Comparisons of thenumber of combinations in different genera listedby Cockayne & Allan with those of recent authorsare more informative. The figures in Table 2 indi-cate that, in those nine genera subjected to recentrevision, the total number of hybrid combinationsis greater than given by Cockayne & Allan. In addi-tion, personal observation of Blechnum and Pterisin the field suggests that there are rather more thanthe two com bination s in each genus listed by Cock-ayne & Allan. I am unaware of any existing evi-dence to support the four combinations listed forHymenophyllum but more detailed morphologicaland cytological investigation of such groups as theH. sanguinolentum/villosum complex might wellreveal hybridisation. The absence of hybridism inthe Cyatheaceae, noted in 1934, seems generallyagreed today, but the remaining four combinationsin various genera listed by Cockayne & Allanrequire further investigation. In summary, there-fore, it seems that the extent of hybridism in theNew Zealand fern flora may actually be greater thansuspected by Cockayne & Allan, with an over-whelming preponderance in Asplenium, followedby Hypolepis, Blechnum, Polystichum, and Pteris.

Unlikefloweringplants where hybrids often showsome degree of fertility, those investigated in fernsare for the most part thought to be effectively ster-ile. All the known combinations in Asplenium, an dall but one in each of Hypolepis an d Polystichum,have mis-shapen spores that are assumed to beinviable, although no detailed germination exper-iments have been carried out. In Doodia X digena,Parris (1972) found that the spores were normal inappearance but did not germinate. There is sup-porting cytological evidence of irregular meioticpairing in at least some hybrids of Asplenium,Hypolepis, Polystichum, and Doodia.In Leptopteris the evidence for hybridisation isbased on biometric analysis of a wild population.

8/7/2019 62===Biosystematics of the NZ Pterydophytes===

3/5

BrownseyBiosystematics: pteridophytes 683Table 2 Comparison of the numbers of hybrid combinations in different fern genera recorded byCockayne & Allan (1934) with those listed in recent revisions.

GenusAspleniumHypolepisPolystichumDoodiaGrammilisLeptopterisBotrychiumLastreopsisLindsaeaTotal:

Numbers of hybridCockayne & Allan

1544101112

29

combinations recorded in N.Z. fern flora

206411*1000

33

Recent revisions(Brownsey 1977b, 1983a)(Brownsey & Chinnock 1984)(Brownsey unpub.)(Parris 1972)(Parris 1977)

(Brownsey 1981)(Braggins 1980)(Tindale 1965)(Kramer & Tindale 1976)

* No hybrids within Grammitis sens. sir. were recorded by P arris & Given (1976), but Parris (1977)reported an intergeneric hybrid Ctenopteris heterophylla X Grammitis bittardieri.

Brownsey (1981) found that the hybrid plants (L .hymenophylloides X superba) showed regular pair-ing of bivalents at meiosis and produced spores ofnormal appearance; germination tests were incon-clusive in that all spores from the parent speciesand the hybrids failed to germinate; however, mor-phological analysis of the wild population clearlyrevealed the presence of the two parent species andFl hybrids, but provided no evidence of F2 plants.By contrast, there is a strong possibility that atleast some Blechnum hybrids may retain a degreeof fertility. Whereas most fern hybrids are foundas single individuals, extensive populations of plantsintermed iate in m orphology between species of theBlechnum "capense" aggregate can often be foundin suitable hab itats. The nature of these plants war-rants a great deal more investigation.

CYTOLOGYThe pioneer in the study of the cytology of NewZealand ferns, still responsible for a majority of thereported chromosome numbers, was Garth Brown-lie, who over a period of 11 years published countsfore. 110 species (Brownlie 1954, 1957, 1958, 1961,1965). Chromosome counts have now beenobtained for about 75% of the native fern taxa. Themajor groups for which counts are still requiredare:i) Lycopodium species, which present technicalproblems but for which a satisfactory techniquenow appears to have been devised (Takamiya

& Kurita 1983).

ii) Grammitis, in which several new taxa haverecently been identified by Parris & Given(1976).iii) Blechnum which, curiously, has never attractedthe cytological attention it deserves (see below),iv) Taxa which are either rare or confined to out-lying islands and which have not been readilyavailable in cultivation.Of those species which have been counted,excluding the Hymenop hyllaceae where base num-bers are difficult to determine, about 54% are poly-ploid. This figure falls within the range of 52-54%given by Walker (1979) for other temperate regions(N. America, Britain, Hungary) and indicates that,in this regard, the New Zealand fern flora is unre-markab le.. However, individual genera showmarked differences in their levels of ploidy in dif-ferent geographical areas notably Aspleniumwhich comprises similar proportions of diploid andtetraploid cytotypes in Europe, but predominantly

tetraploid and octoploid cytotypes in New Zealand,with diploids absent (Lovis 1973, Brownsey 1977a).It is also surprising to find that only three or fourNew Zealand ferns (c. 2%) are suspected of beingapomictic, and that none of them are endemic.No serious attempt has yet been made to emu-late the detailed cytogenetic investigation of wildand artificially-produced hybrids that has yieldedsuch a wealth of information on the evolutionaryorigins of European and North American ferns,especially in the genera Asplenium, Cystopteris,Dryopteris, and Polypodium (Lovis 1977). Suchresults as have been obtained from New Zealandwild hybrids in Doodia (Brownlie 1961), Asplenium

8/7/2019 62===Biosystematics of the NZ Pterydophytes===

4/5

684 New Zealand Journal of Botany, 1985, Vol. 23(Brownsey 1977b), and Hypolepis (Brownsey &Chinnock 1984) indicate a pattern of chromo soma lpairing at meiosis consistent with th at seen in o therparts of the world. On the basis of morphology andploidy level, Brownsey (1977b) suggested a possibleauto- or allopolyploid origin for a number of octo-ploid Asplenium species from extant tetraploids,but, with chromosome numbers ranging up to 288in 8 genome sets, it is unlikely that meiotic analysiswill ever reach the degree of sophistication neces-sary to provide the cytogenetic basis for thishypothesis.

CHEMOTAXONOMYChemotaxonomy of New Zealand ferns is still inits infancy and has so far been confined almostentirely to flavonoid chemistry. Because of the needfor specialised facilities, virtually all the work hasemanated from, or been associated with, KenMarkham's laboratory at Chemistry Division,DSIR. Primitive groups of pteridophytes, notablyPsilotaceae (Wallace & Markham 1978), Lycopo-diaceae (Markham et al. 1983), Loxsomataceae(Markham & Given 1979), Hymenophyllaceae(Markham & Wallace 1980), and Gleicheniaceae(Wallace et al. 1983), have so far received the great-est attention, but the results indicate that moredetailed studies of these and other groups can beexpected to provide real assistance in the taxon-omic subdivision of large families such as the club-mosses and filmy ferns, and in determining thephylogenetic affinities of isolated genera like Stro-matopteris and Loxsoma.

FUTURE DIRECTIONSNew Zealand pteridology is now at a point wherethe basic taxonomy is largely complete and we canlook forward to the preparation of a sound Floraand to investigating in more detail the biosyste-matics of a number of evolutionarily interestinggroups. There will, of course, be a continuing num -ber of small taxonomic problems in specific areas,and , for a wh ile at least, the occasional new species.More attention can be given to polymorphism inindividual taxa for example, to the problem ofwhy Asplenium hookerianum (sens, lat.) so fre-quently exhibits sympatrically two markedly dif-ferent frond forms, or to the significance ofdifferences in hair covering observed in differentpopulations of Adiantum hispidulum (sens. lat.). Ona grander scale, however, local botanists are wellplaced to make a major contribution to the studyof such widespread families as Blechnaceae,

Lycopodiaceae, and Hymenophyllaceae by a coor-dinated morphological, cytological, and phyto-chemical investigation of the New Zealandrepresentatives. Blechnum is perhaps uniquelysuitable for a joint approach of this kind, havingpolyploid derivatives superimposed on a well-defined aneuploid series. The chromosomes areamenable to mitotic investigation, and one couldreasonably expect to determine the direction ofevolution in the aneuploid series by morphologicaland phytochemical analyses. Furthermore, the localspecies can, in many cases, be related to presumedancestral types in Australia and S.E. Asia, whichopens up a whole new field of study. The relation-ship of New Zealand ferns, in general, to theirAustralian counterparts also deserves more carefulappraisal. Are Dicksonia antarctica and D. fibrosa,or Pilularia novae-hollandiae an d P. novae-zelan-diae , really different species? Conversely, is theQueensland Adiantum cunninghamii really thesame as the New Zealand species? Why hav e someAustralian species, like Adiantum formosum, neverbecome more widespread in New Zealand inapparently suitable habitats? Is the newly describedsexually reproducing Cheilanthes austrotenuifolia(Quirk et al. 1983), which is widely distributed intemperate Australia, also present in New Zealand,or is the genus represented here only by apomicticspecies? Does the greater variation in the NewZealand Asplenium flaccidum/terrestre aggregateindicate diversification and speciation in animpoverished flora on this side of the Tasman Sea,or do the more uniform populations in Australiasuggest earlier speciation and subsequent drasticextinction of all but the best adapted forms in thatregion? Whatever the answers to these and otherquestions, there is no doubt that the biosystematicproblems become more interesting as better tax-onomy provides a clearer field of view.

REFERENCESAllan, H. H . 1961: Flora of New Z ealand, V ol. I. Wel-lington, Government Printer.Braggins, J. E. 1980: Some studies on the New Zealandspecies of Botrychium Sw. (O phioglossaceae). NewZealand journal of botany 18 : 353-366.Brownlie, G. 1954: Introductory note to cytotaxonomicstudies of New Zealand ferns. Transactions of theRoyal Society of New Zealand 82 : 665-666.

1957: Cytotaxonomic studies on New ZealandPteridaceae. New phytologist 56 : 207-209.1958: Chromosome numbers in New Zealandferns. Transactions of the Royal Society of NewZealand 85: 213-216.1961: Additional chromosome numbers New Zealand ferns. Transactions of the RoyalSociety of New Zealand (Botany) 1: 1-4.

8/7/2019 62===Biosystematics of the NZ Pterydophytes===

5/5

BrownseyBiosystematics: pteridophytes 6851965: Chromosome numbers in some PacificPteridophyta. Pacific science 19 : 493-497.

Brownsey, P. J. 1977a: A taxonomic revision of the NewZealand species of Asplenium. New Zealand jour-nal of botany 15 : 39-86.1977b: Asplenium hybrids in the New Zealandflora. New Z ealand journal of botany 15 : 601-637.1981: A biosystematic study of a wild popu-lation of Leptopteris hybrids in New Zealand. NewZealand journal of botany 19: 343-352.1983a: Asplenium terrestre and two Aspleniumhybrids: new fern records for Australia. Muelleria5: 219-221.1983b: Bryophytes and pteridophytes. In :Brownsey, P. J.; Baker, A. N. (ed.), The NewZealand biota w hat do we know after 200 years?National Museum of New Zealand MiscellaneousSeries 7: 17-27.

Brownsey, P. J.; Chinnock, R. J. 1984: A taxonomic revi-sion of the N ew Zealand species of Hypolepis. NewZealand journal of botany 22:43-80.Brownsey, P. J.; Given, D. R.; Lovis, J. D. 1985: A revisedclassification of New Zealand pteridophytes witha synonymic checklist of species. New Zealandjournal of botany 23 : 431-489.Chinnock, R. J. 1975: The New Zealand species of Tme-sipteris (Psilotaceae). New Zealand journal ofbotany 13: 743-768.Cockayne, L.; Allan, H. H. 1934: An annotated list ofgroups of wild hybrids in the New Zealand flora.Annals of botany 48 : 1-55.Kato, M. 1984: A taxonomic study of the athyrioid ferngenus Deparia with main reference to the Pacificspecies. Journal of the Faculty of Science, Univer-sity of Tokyo, Section III, 13: 375-429.Kramer, K. U.; Tindale, M. D. 1976: The Lindsaeoid fernsof the Old World VII. Australia and New Zealand.Telopea 1: 91-128.Lovis, J. D. 1973: A biosystematic approach to phylo-genetic problems and its application to the Asplen-iaceae. In : Jermy, A. C. et al., The phylogeny andclassification of the ferns. Botanical Journal of theLinnean Society 67 (Supplement No. 1) : 211-227.

1977: Evolutionary patterns and processes inferns. Advances in botanical research 4 : 229-415.Markham, K. R.; Given, D. R. 1979: The flavonoids offerns in the isolated genera Loxsoma and Loxso-mopsis. Biochemical svstematics an d ecology 7 : 9 1 -93 .Markham, K. R.; Moore, N. A.; Given, D. R. 1983: Phy-tochemical reappraisal of taxonomic subdivisionsof Lycopodium (Pteridophyta Lycopodiaceae)based on flavonoid glycoside distribution. NewZealand journal of botany 21 : 113-120.Markham, K. R.; Wallace, J. W. 1980: C-glycosylxan-thone and flavo noid variation within the filmy ferns(Hymenophyllaceae). Phytochemistry 19 : 415-420.Parris, B. S. 1972: The genus Doodia R. Br. (Blechnaceae:Filicales) in New Zealand. New Zealand journal ofbotany 10: 585-604.

1977: A naturally occurring intergeneric hybridin Grammitidaceae (Filicales): Ctenopteris hetero-phylla X Gram mitis billardieri. N ew Zealand jour-nal of botany 15 : 597-599.Parris, B. S.; Given, D. R. 1976: A taxonomic revisionof the genus Grammitis Sw. (Grammitidaceae: Fil-icales) in New Zealand. New Zealand journal ofbotany 14: 85-111.Quirk, H.; Chambers, T. C; Regan M. 1983: The ferngenus Cheilanthes in Australia. Australian journalof botany 31 : 501-553.Takamiya, M.; Kurita, S. 1983: Cytotaxonomic studieson Japanese species of the genus Lycopodium sensulato. Ada Phytotaxonomica Geobotanica 34 : 66-79.Tindale, M. 1965 : A monograph of the genus Lastreopsis

Ching. Contributions from the New South WalesNational Herbarium 3 : 249-339.Walker, T. G. 1979: The cytogenetics of ferns. In : Dyer,A. F. (ed.), The experimental biology of ferns.Academic Press, London.Wallace, J. W.; Markham, K. R. 1978: Apigenin andamentoflavone glycosides in the Psilotaceae andtheir phylogenetic significance. Phvtochemistry 17:1313-1317.Wallace, J. W.; Pozner, R. S.; Gomez, L. D. 1983: A phy-tochemical approach to the Gleicheniaceae. Amer-ican journal of botany 70 : 207-211.