Weed Identification: Using Plant Structures as a...
18
Paul A. Baumann Professor and Extension Weed Specialist, The Texas A&M University System. B-6079 3-99 Using Plant Structures as a Key Weed Identification:
Transcript of Weed Identification: Using Plant Structures as a...
Paul A. BaumannProfessor and Extension Weed Specialist, The Texas A&M University System.
B-60793-99
Using PlantStructures
as a Key
Weed Identification:
eed
iden
tifi
cati
on is
nec
essa
ry t
oth
e su
cces
s of
any
wee
d co
ntro
lpr
ogra
m. F
requ
entl
y, s
impl
e pl
ant
keys
or
“pic
ture
boo
k” id
enti
fica
tion
gui
des
are
used
to
iden
tify
wee
ds. H
owev
er, s
ome
plan
tta
xono
my
keys
can
be
quit
e co
mpl
ex a
nd r
equi
rean
adv
ance
d un
ders
tand
ing
of p
lant
str
uctu
rean
d ta
xono
mic
ter
min
olog
y. W
hile
mor
e di
ffic
ult
to u
se, a
det
aile
d ke
y or
gui
de a
llow
s fo
r th
epr
ecis
e id
enti
fica
tion
of
wee
ds.
Thi
s ha
ndbo
ok is
inte
nded
for
use
as
aco
mpa
nion
pie
ce t
o be
tter
und
erst
and
the
plan
tpa
rt t
erm
inol
ogy
used
in le
ss c
ompl
icat
edid
enti
fica
tion
gui
des.
W
Introduction
1
ClassificationW
eeds
can
be
clas
sifie
d in
to o
ne o
f thr
eedi
ffer
ent
cate
gori
es: b
road
leav
es, g
rass
esor
sed
ges.
Bro
adle
af w
eeds
oft
en a
re r
efer
red
toas
dic
ots;
the
see
dlin
gs p
rodu
ce t
wo
coty
ledo
ns(s
eed
leav
es) t
hat
are
evid
ent
as t
he p
lant
em
erge
sth
roug
h th
e so
il su
rfac
e. B
road
leaf
pla
nts
gene
rally
hav
e w
ider
leav
es t
han
gras
s pl
ants
and
the
stem
s ar
e of
ten
bran
ched
. Lea
f vei
nati
on is
netl
ike
or h
as a
bra
nche
d ap
pear
ance
.
Gra
sses
and
sed
ges
are
mon
ocot
s; t
heir
seed
ling
s pr
oduc
e on
ly o
ne c
otyl
edon
(so
met
imes
refe
rred
to
as t
he c
oleo
ptil
e in
gra
sses
). G
rass
esha
ve b
lade
d le
aves
tha
t ar
e pa
rall
el v
eine
d an
dth
is v
eina
tion
ext
ends
ont
o th
e sh
eath
. In
cros
s-se
ctio
n, t
he s
tem
s in
gra
sses
are
usu
ally
rou
ndor
som
ewha
t fl
atte
ned.
The
ste
ms
of s
edge
s, in
cros
s-se
ctio
n, a
re u
sual
ly t
rian
gula
r.
Ase
cond
, rel
ativ
ely
sim
ple
met
hod
of w
eed
clas
sifi
cati
on is
by
the
cate
gori
es o
f an
nu
als,
bie
nn
ials
or p
eren
nia
ls.A
nn
ual
pla
nts
live
for
one
grow
ing
seas
on a
nd a
re o
ften
ref
erre
d to
as e
ithe
r su
mm
er a
nnua
ls o
r w
inte
r an
nual
s.S
um
mer
an
nu
als
germ
inat
e fr
om s
eed
in t
hesp
ring
, pro
duce
veg
etat
ive
grow
th, s
et f
low
eran
d pr
oduc
e fr
uit
mid
- to
late
sum
mer
, and
die
back
in t
he f
all.
Win
ter
ann
ual
sge
rmin
ate
inth
e la
te s
umm
er t
o ea
rly
fall
, pro
duce
veg
etat
ive
grow
th, f
low
er a
nd p
rodu
ce s
eed
in m
id-
to la
tesp
ring
, and
die
off
in t
he s
umm
er.
2
Bie
nn
ials
are
plan
ts t
hat
live
for
tw
o ye
ars;
seed
s ge
rmin
ate
in t
he s
prin
g, s
umm
er o
r fa
ll o
fth
e fi
rst
year
and
the
pla
nts
over
win
ter
usua
lly
as a
ros
ette
of
leav
es. D
urin
g w
inte
r, t
he s
hoot
tips
are
exp
osed
to
cold
tem
pera
ture
s fo
r a
peri
od o
f ti
me.
Thi
s ve
rnal
izat
ion
prom
otes
norm
al d
evel
opm
ent
of f
low
erin
g an
d se
edpr
oduc
tion
dur
ing
the
sum
mer
of
the
seco
ndye
ar. T
he p
lant
s th
en d
ie in
the
fal
l.
Per
enn
ials
are
plan
ts t
hat
prod
uce
vege
tati
vest
ruct
ures
tha
t al
low
the
m t
o liv
e fo
r th
ree
orm
ore
year
s. T
hese
pla
nts
are
clas
sifi
ed a
s si
mp
leor
cre
epin
g p
eren
nia
ls.S
imp
le p
eren
nia
lssp
read
pri
mar
ily b
y se
ed; t
hey
cann
ot s
prea
dve
geta
tive
ly fr
om u
nder
grou
nd r
oots
. Cre
epin
gp
eren
nia
ls, o
n th
e ot
her
hand
, can
rep
rodu
ce b
ycr
eepi
ng r
oots
and
als
o th
roug
h se
ed p
rodu
ctio
n.T
he c
reep
ing
root
s fo
und
abov
e gr
ound
are
cal
led
stol
ons,
the
belo
w-g
roun
d ro
ots
are
calle
drh
izom
es. R
hiz
omes
are
mos
t co
mm
on in
pere
nnia
l gra
sses
. In
broa
dlea
fs o
r se
dges
, the
seun
derg
roun
d ro
ot s
truc
ture
s ar
e re
ferr
ed t
o as
tub
ers.
3
The
fir
st s
tep
in id
enti
fyin
g gr
ass
wee
ds is
to
beco
me
fam
ilia
r w
ith
som
e ke
y gr
ass
part
s:th
e le
af b
lad
e, t
he
coll
ar, t
he
ligu
lean
d th
esh
eath
.The
lig
ule
may
or
may
not
be
pres
ent
on s
ome
gras
s se
edli
ngs.
The
sh
eath
is a
nex
tens
ion
of t
he le
af b
lade
tha
t te
rmin
ates
at
the
node
. The
are
as b
etw
een
the
nod
esar
e re
ferr
edto
as
inte
rnod
es.S
ome
gras
s pl
ants
may
hav
eex
tens
ions
of
the
shea
th c
alle
d au
ricl
es.A
sedg
e, h
owev
er, g
ener
ally
doe
s no
t ha
ve a
ligu
leor
an
auri
cle.
leaf
bla
de
ligul
e
auri
cle
leaf
col
lar
shea
th
node
Plant Parts
4
The
cro
ss-s
ecti
ons
of g
rass
es m
ay b
e ei
ther
rou
nd
or o
val
(fla
tten
ed),
com
pare
d to
ase
dge,
whi
ch e
xhib
its
a tr
ian
gula
rsh
ape.
The
sh
eath
of a
gra
ss s
urro
undi
ng t
he s
tem
isge
nera
lly o
ne o
f thr
ee t
ypes
: sp
lit,
ove
rlap
pin
g,or
un
ited
.
split
over
lapp
ing
unite
d
5
The
ligu
leon
a g
rass
pla
nt is
a s
truc
ture
on
the
insi
de o
f the
col
lar.
It c
an b
e ei
ther
mem
bra
nou
sor
hai
ry,o
r it
may
not
be
pres
ent
at a
ll.
The
ligu
le m
ay e
xhib
it e
ithe
r a
smoo
th m
argi
nor
a t
ooth
ed m
argi
n.
Au
ricl
es,a
ppen
dage
s fo
und
at t
he ju
ncti
on o
fth
e le
af b
lade
and
leaf
she
ath,
may
or
may
not
be p
rese
nt.
abse
ntha
iry
mem
bran
ous
smoo
th li
ngul
em
argi
nto
othe
d lin
gule
mar
gin
auri
cles
pre
sent
auri
cles
abs
ent
6
Pu
bes
cen
ceor
lea
f h
air
is o
ften
a k
ey t
oid
enti
fyin
g sp
ecif
ic g
rass
es a
nd w
eeds
.P
ubes
cenc
e ca
n ap
pear
in s
ever
al d
iffe
rent
are
ason
a g
rass
pla
nt:
• on
ly o
n th
e sh
eath
mar
gin,
•
over
the
ent
ire
outs
ide
of t
he s
heat
h su
rfac
e,•
on t
he le
af c
olla
r m
argi
n,
• as
a r
ing-
like
app
eara
nce
surr
ound
ing
the
who
le c
olla
r,•
on t
he le
af b
lade
mar
gins
or
leaf
edg
es, o
r•
only
on
the
blad
e su
rfac
e, w
ith
hair
abs
ent
over
the
oth
er p
arts
of
the
plan
t.
Lea
ves
or o
ther
pla
nt s
urfa
ces
wit
hout
any
pube
scen
ce w
hats
oeve
r ar
e of
ten
refe
rred
to
as g
lab
rou
s.
hair
y sh
eath
mar
gin
hair
y sh
eath
hair
y co
llar
mar
gin
hair
y co
llar
hair
y le
afm
argi
nha
iry
leaf
blad
e
7
Are
pres
enta
tion
of
a br
oadl
eaf
plan
t w
ith
a fe
wke
y de
scri
ptiv
e pa
rts
labe
led
is s
how
n ab
ove.
true
leaf
term
inal
bud
leaf
bla
de leaf
vei
nsal
tern
ate
leaf
ar
rang
emen
tpe
tiole
stem
coty
ledo
n
root
s
8
Bro
adle
af w
eed
coty
led
ons
are
a ke
yid
enti
fica
tion
fea
ture
. How
ever
, if
coty
ledo
nsha
ve f
alle
n of
f th
e pl
ant
or a
re in
poo
r co
ndit
ion,
they
may
not
be
help
ful i
n br
oadl
eaf
wee
did
enti
fica
tion
. Var
ious
cot
yled
on s
hape
s ar
eil
lust
rate
d ab
ove.
linea
rob
long
lanc
eola
te
spat
ulat
eov
alro
und
ovat
eki
dney
butt
erfly
9
Usi
ng c
otyl
edon
s w
ith
tru
e-le
afid
enti
fica
tion
feat
ures
can
hel
p in
the
ove
rall
wee
did
enti
fica
tion
pro
cess
. Tru
e le
aves
gen
eral
lyex
hibi
t on
e of
sev
eral
leaf
sha
pes
sim
ilar
to
coty
ledo
ns.
filifo
rmlin
ear
lanc
eola
teob
lanc
eola
te
spat
ulat
eob
ovat
eov
ate
cord
ate
oblo
ngro
und
sagi
ttat
e
10
Lea
f m
argi
ns
(lea
f bl
ade
edge
s) a
lso
are
spec
ial
feat
ures
for
iden
tify
ing
spec
ific
pla
nts.
Exa
mpl
esof
en
tire
, ser
rate
d, p
inn
atel
y lo
bed
and
pal
mat
ely
lob
edle
af m
argi
ns a
re s
how
n.
Pin
nate
ly lo
bed
leav
es c
an b
e di
stin
guis
hed
from
palm
atel
y lo
bed
leav
es b
y ex
amin
ing
the
vein
son
the
leav
es. I
n a
pinn
atel
y lo
bed
leaf
, the
vei
nsw
ill a
rise
fro
m s
ever
al p
oint
s al
ong
a ce
ntra
lax
is. A
palm
atel
y lo
bed
leaf
has
vei
ns t
hat
aris
eat
the
sam
e po
int
at t
he b
ase
of t
he le
af.
entir
ese
rrat
ed
pinn
atel
y lo
bed
palm
atel
y lo
bed
11
Lea
f ar
rang
emen
t on
the
pla
nt c
an b
e ei
ther
alte
rnat
e, o
pp
osit
eor
wh
orle
d.
Att
ach
men
tto
the
ste
m is
ref
erre
d to
in o
ne o
fth
ree
way
s:•
pet
iola
te, w
here
a p
etio
le e
xist
s be
twee
n th
e le
af, b
lade
and
the
ste
m;
• se
ssil
e, w
here
the
re is
ess
enti
ally
no
peti
ole
and
the
leaf
bas
e is
att
ache
d di
rect
ly t
o th
e st
em; o
r •
clas
pin
g,w
here
the
bas
e of
the
leaf
par
tial
ly
surr
ound
s th
e st
em.
alte
rnat
eop
posi
te
who
rled
petio
late
sess
ilecl
aspi
ng
12
Indi
vidu
al l
eafl
ets
may
be
clas
sifi
ed a
s ei
ther
sim
ple
or c
omp
oun
d. W
ithi
n co
mpo
und
leav
es, t
here
exi
sts
eith
er p
inn
atel
yco
mp
oun
dor
pal
mat
ely
com
pou
nd
leaf
char
acte
riza
tion
s.
Lea
f vei
nat
ion
is d
iffer
ent
for
both
gra
sses
and
broa
dlea
f pla
nts.
Vei
nati
on in
gra
ss p
lant
s is
ap
aral
lelt
ype.
Bro
adle
af p
lant
s m
ay e
xhib
itei
ther
a p
alm
ate
vein
atio
n or
pin
nat
eve
inat
ion.
palm
ate
vein
atio
npi
nnat
e ve
inat
ion
sim
ple
com
poun
d
pinn
atel
y co
mpo
und
palm
atel
y co
mpo
und
13
Som
e br
oadl
eaf
plan
ts m
ay h
ave
othe
r pe
culi
arch
arac
teri
stic
s su
ch a
s an
ocr
ea.T
his
is a
mem
bran
ous
tubu
lar
shea
th t
hat
surr
ound
s th
est
em a
t th
e ba
se o
f th
e pe
tiol
e.
Veg
etat
ive
repr
oduc
tive
str
uctu
res
also
may
be
used
as
key
plan
t id
enti
ficat
ion
feat
ures
.R
hiz
omes
are
basi
cally
ste
ms
that
dev
elop
bel
owgr
ound
. Pla
nt s
hoot
s ca
n ar
ise
from
und
ergr
ound
node
s on
the
se s
tem
s.
ocre
a
soil
surf
ace
rhiz
ome
node
s
14
Tu
ber
sar
e th
icke
ned
unde
rgro
und
stem
s th
atde
velo
p at
the
end
of
rhiz
omes
. Sto
lon
sar
ero
ots
that
gro
w h
oriz
onta
lly
abov
e th
e gr
ound
.R
oots
oft
en d
evel
op a
t th
e no
des
of s
tolo
ns a
ndpe
g do
wn
into
the
soi
l. N
ew s
hoot
s al
so d
evel
opat
the
se s
ites
.
tube
rs
soil
surf
ace
stol
on 15
The
se d
epic
tion
s of
pla
nt p
arts
can
ser
ve a
s a
sim
ple
guid
e to
und
erst
andi
ng t
hete
rmin
olog
y in
sim
ple
fiel
d gu
ides
or
plan
t ke
ysus
ed f
or w
eed
iden
tifi
cati
on. T
he u
se o
f m
ore
com
plic
ated
key
s fo
r pl
ant
iden
tifi
cati
on m
ayre
quir
e a
thor
ough
und
erst
andi
ng o
f pl
ant
vege
tati
ve a
nd f
low
erin
g pa
rts.
Use
16
