Table Of Contentt
SOLIDAGO
PAPPUS VARIATION
IN
(ASTERACEAE; ASTEREAE)
L.A.Hood John C.Semple^
Jennifer
Department
of Biology
compared.ath variati[on in 14 spec:ies of 12 related genera in subtribe Solidagi ninae in the narrow
sense followingNesom (2000) and hreespeci es of asters of two genera basal to the North A,merican
I
Cladeofthe tribe. SoUdago has beer describeelas having a simple pappus consi<.tmg of one whorl of
1
m
ristles wit htheexcepti on of a fev species several sections, some
/
SoMago Corymb
tinct genera Species sec o..e(Oligoneuron) have long bee,n recognizee as hav-
oi X.
I
. 1
pappus milar to that of other genera of th
,te
m
nearly all species of Sc,Hdagodispklyed some evidence indicating the pappus gristles occu r two
1
more or less heteromorphic whorls of bristle; here designated as the primary outer whori and the
;,
Jew much
primary inner whorl, species dsooccasicmally had a third, shorter se condaryoutijr whorl
y^ a
of a few bristies. In the most heterornorphicsr)ecies, the primary outer whorl of bristles was slightly
shorter and had tips th gradually he primary inner whorl of slightly longer bris ties had
.at
As well, the bases of
the primary outer wh(xl were clearfy externa to those of the primary inner avate whorl in some
cl;
1
m
species. In contrast, ost species in several jbsections of the genus exhibitec little evide nee of a
si
1
non-clavate to distinct] yclavatebristie tips, 2). eandclavate bristles
md w
or shorter a nd longer bristles, and 3) evident;e of overlapping primary outer inner horls of
;
bristles. One species of SoHdago had anatypiailly short pappus; the bristles of 5. sphacdata were less
:
than half the length ofthecypsela body The biseriate pappus of Brintonia di scoidea was usually
:
m
tinted with;mthocyan otic pigment. unlike arly species of SoMago; the species!las been inclluded
s
Solidagohy.someauth.
RESUMEN
Se examine el vilano e n 75 especies del generoSol.dflgoCAsteraceaeiAstereae) y se compar 6 con la
,
variacionen MespeciesdeI2generc idosdelasubtribuSolidagininaee]nsentidorestringido
'srelacionj
INTRODUCTION
l^reviously the genus Solidago L. was considered different from closely related
genera in regards to pappus characteristics. While related taxa such as
its
Scricocarpus Nees, Tonestus A. Nels., Petradoria E.L. Greene, Chrysothamnus
Nutt. and Ericameria Nutt. were considered to have a pappus in 2-3 series (1-2
genus was pappus
for Tonestus), the Solidago stated to have a in a single series
Nesom
Semple
leg., et al. 1999; 2000). has also been described as simple
It
Some
iFernald 1950; Correll 1970). treatments do not mention anything
et
al.
about the seriate nature of the pappus in the genus description (Radford et
al.
968; Cronquist, 1980; Gleason and Cronquist 1991), although variations are in-
1
Some
dicated in species descriptions. treatments state that the pappus of Sol-
idago exhibits some variation. Gleason and Cronquist recorded the pap-
(1991)
bcmg
numerous
pus as "of equal or sometimes unequal capillary
bristles" for
species from the northeast U.S.A. and adjacent Canada, while Cronquist (1994)
noted the pappus as being "equal or sometimes somewhat unequal" in Great
Some
Basin species. of the differences in description are due to differences in
which
taxa were included in the genus Solidago, particularly the generally rec-
&
ognized clavate tipped members of Solidago Corym hosae Torrey A. Gray
sect.
Tor example, Cronquist (1980) included these flat-topped goldenrods, but ex-
Bnntoma
Mock
cluded
discoidca (Elliott) E.L. Greene, the Goldenrod. In con-
Nesom
trast, (2000) excluded the former species placing them in the genus
Oligoncuron Small, but included Bnntonia discoidea as discoidca (Elliott)
5.
&
Nesom
Torrey A. Gray. (1991) discussed morphological reasons treating
for
B.
discoidca within Solidago. Semple (submittted) treated Brintonia separate
as a
genus based on morphology (phyllary pappus
disc corolla
traits, traits, traits),
DNA
field observations and studies (Beck and colleagues, pers.comm.).SohJago
sphacdata Rah has been treated as Brachychaeta sphacelata (Raf.) Britt. due to
Nesom
within (Cronqmst Semple and
Solidago 1980; 1991, 1993; Cook, submit-
m
Other authors the past have included Euthamia
ted). (Nutt.) Nutt.,
Oreochrysum Rydberg, or Petradoria in Solidago, there by increasing the range
pappus within genus Fernald Kearney
of variation in traits the latter 1950;
(e.g.,
&
Harrington Semple
Peebles 1951; 1964; et 1999).
al.
The pappus shape have generally been overlooked and
details of bristle
descriptions have included various terms. Most have described the pappus of
Solidago as "capillary" or "hair-like" (Fernald 1950; Radford et 1968; Correll
al.
&
&
Some
Johnston Cronquist Gleason Cronquist
1970; 1980, 1994; 1991).
ments mention the pappus of Solidago as being "barbellate" or "clavate" in
&
SempL
species (Cronquist 1980, ptarmicoides (Torrey A. Gray) Boivin;
5.
&
1999, houghtonh Torrey A. Gray, ptarmicoides (as asteroides Semple),
S. S. S.
S.
sempervirens Pappus bristles of Solidago and closely genera have been de-
L.).
Nesom
(Nesom
scribed as being "barbellate" 2000). (1993) in his overv:
Solidago and Oligoneuron used pappus bristle apex features as taxonomic char-
and toward
acters: "strongly clavate," "attenuate," "slightly but distinctly dilated
He and and noted
the apex." listed these in descriptions of sections subsections,
the character state of pappus bristles for some species in particular
The pappus has long been reported
occurrence of a biseriate to multiseriate
in other genera in the Tribe Astereae in both the North American Clade, which
Semple and Grade South Ameri-
includes Solidago 2002), the Basal of
(see et
al.
can and Old World Genera. The more basal genera in the North American Clade
These
are biseriate or triseriate with bristles of equal or different lengths. in-
clude most of the genera included traditionally in the Old World genus Aster
Oclemena
Bucephalus Greene,
Doellingeria Nees, Nutt., lonactis E.L. E.L.
L.:
Nesom
Greene, Sericocarpus. Most species in subtribe Chrysopsidinae are
much
having short outer whorl and a longer inner whorl. In con-
biseriate, a
Symphyotrichum
the pappus of some genera typically uniseriate,
trast, is e.g.
Nees. In some cases the usual barbellate bristles are absent or very reduced,
e.g.
The
Aphanostephus DC.
ray floret cypselae of Heterotheca sect. Heterotheca,
number between within and between genera
of bristles varies greatly species
Thus, within the North American Clade of genera of Astereae there
as well.
number and shapes
exists a range in the of whorls, their relative lengths their
No
Nesom 2000 general descriptions of genera). detailed systematic
(see for
examination of the pappus of most or all species of Solidago has been reported.
m
Our was undertaken gap knowledge.
study to in this
fill
AND METHODS
MATERIALS
A
preliminary survey was undertaken examine under the dissecting micro-
to
scope the pappus bristles of one or two specimens of representative species of
more
and Subsequently rigorous survey
the sections subsections of Solidago. a
was conducted involving 75 species of Solidago and 17 species of 14 other gen-
m
era listed Table Two methods of observation were employed, and a system
1,
was Most
developed. ob-
of ranking the degree of the clavateness of bristle tips
plumosa
S.
spathulata
S.
^bseclThyrsiflorae
(/
flexicaulis
S.
lancifolia
S.
V
Clavate^ Alternating Overlappim
Brachychaeta &
(Torrey Gr
A.
r.
Junceae (Rydberg) Nesor
)secx.
thickened length,
.(slight)
AGO
SOLID COfiVMeOS/Af &
L. sect. Torrey A. Gre
Clavate' Alternating
oregonensis
S.
Bucephalus
breweri
E.
elegans
E.
made
servations were using a dissecting scope or a compound light microscope.
Some made
observations were using dried and gold coated specimens on
a
litachi S-570 Scanning Electron Microscope (SEM). At
least five different fruits
1
Irom
eacfi species were observed under the dissecting microscope maxi-
at a
mum
of 70x; most observations were made at 30x. In some cases multiple doz-
ens of specimens of a species were examined. For the most part, observations
WAT
made
were on specimens
in the Herbarium, but additional material on
TEX UC
loan from BRIT, GH, JEPS, NY, and (Holmgren 1990) was
F, et al. also
compound
l^bscrvations on the microscope were made from
slides pre-
pared as lollows. For each species, two ray floret and two disc floret cypselae
were mounted DepeX mountmg medium
ciMollas under
ith in cover
\\ a
slip.
C^hsLTvat ions lOOx on the compound microscope were made
at similarly the
to
obser\'ai ions under the dissecting scope 30x-70x. Observations made on
at the
two nds scopes were compared and any
k of discrepancies were resolved by
re-
i
Each taxon was scored the following manner:
in
Cypselae were assigned number from 0-4 depending on
1. a the thickness
of the tip of the bristle in relation to the thickness along the length; = no ob-
servable increase thickness and
in the bristles tapered to a point (Fig. = a
1
1);
very
slight increase thickness near
in the tip, or the bristles not tapering gradu-
m
= moderate
ally; 2 a slight to increase thickness near the 3 =
tip (Fig. a
2);
and
strong obvious presence of clavate and 4 = very
tips; noticeable increase in
thickness, very obvious clavate nature of the A
bristles (Fig. set of reference
3).
2. Cypselae were scored as showing no evidence of alternation of primary
and
niner outer whorls showing
of bristles or as evidence of alternating with
on
he notes the nature of the alternation (No or Yes in Table respectively).
t 1,
Cypselae were
3. scored for evidence of overlapping at the bases of the outer
and inner whorls The examined
of bristles. taxa were graded in three catego-
ries regarding the overlapping of the bristles at the base: Yes = complete overlap
of bristles; Yes (slight) = slightly overlapping with outer whorl
bristles consis-
appearing
tently external to inner whorl and Yes (random) =
bristles; overlap-
some
ping
of outer bristles external to inner bristles but not consistently so for
thetwowhoris.
made when
Notes were
4. a secondary outer whorl whorl)
(a third of very
was
short barbel Such
late bristles observed. bristles were not easily observed
and occurred low numbers,
in thus the presence absence such was
or of
bristles
not
tabulated.
photomicrographs
Digital were taken using Nikon CoolPix 990 camera
a
manually
held against the ocular lens of either the dissecting or compound
1-3. Pappus
bristle tip
Figs.
bristle tip, 5.p/neforu/n(0value in Table 1).2. Weakly cla\
value Table
bristle tip, 5. crecffl (4 in 1).
compound
microscope. Pictures were taken of specimens under the light mi-
SEM
photomicrographs
croscope with either below stage or above stage lighting.
made using Ilform Pan F film mercially developed and subsequently
t
made
were using
by scanning the negal digital illustrations
ized al
Draw 10® from ges edited with Corel PhotoPamtlO® (Corel Corp.).
digital
AND
RESULTS DISCUSSION
and
pappus whorls
The lack of adard set of terms for bristle in So\\d.ago
c
between
other genera lead to some confusion in discussing the results the au-
thors and for the reviewer The following labels are presented as potential fu-
"standard" terms discussing pappus whorls in the Astereae. Because a
ture for
many we recommend
biseriate pappus found in genera of the tribe, that these
is
and
two whorls of bristles be referred to as the "primary outer whorl" the "pri-
mary The primary inner whorl often longer and has slightly to
inner whorl."
is
much
The outer whorl present
strongly clavate bristle tips. third, often shorter,
These
in some genera can be referred to as the "secondary outer whorl." labels
The
paper term
whorls used consistently throughout this "sec-
for bristle are
any
ondary" with appropriate modifiers can be applied to additions whorls, e.g.
secondary innermost whorl of non-clavate long bristles.
a
although obscurely
The pappus the genus SoXidago usually biseriate,
of
is
so in some species. In most species the pappus exhibited either alternation of
some
degree basal overlapping outer and mncr primary
ol oi bristles ol the
and
inner outer whorls. Table lists observations on the degree of clavateness
1
ol bristle tips, presence or absence of evidence of alternation of whorls of
bristles, degree of basal overlapping of outer and inner long whorls, and spe-
observations on and
cilic 75 species of Solidago 17 species of 14 related genera.
Species ol Sohday^o are grouped within Table by section, subsection and
series
1
lowing the rear mcnt of the genus by Semple (Semple Semple
lol 1999; 2003;
et al.
I
subm
Semple, Cook and Semple, submitted, treatment
irted; of Solidago Flora
for
North America). There a large range in size the cypsclae bodies and length
is of
pappus among much
ol the bristles species ol So/k/i/^i^oU'igs 4-9j Bristles can be
shorter than to four times longer than the and length ranged
uit bod\', bristle
1 1
mm
rom mm.
0.25-7.5 Cypsela bodies varied Irom 5-5 length and from
in
I
glabrous to densely short strigose. The number ol bristles per cypsela ranged
rom
about 25 (Fig. 9 S. canadensis) to more than 40 (Fig. auriculata). On
6, S.
I
,
pappus
average, bristles were slightly shorter than the disc corollas (averaging
about 9/10 as long comparing the mature pappus
to the disc corolla length
at
anthesis based on data in Semple and Cook, submitted).
Some
pappus
ot the bristles in the majority of species of Solidago were ob-
more
served to be or less clavatc, and these were the primary inner whorl
bristles
m
where
taxa position of the whorls could be determined. About 25%
of the
examined
species had, relative to other species, broad clavate bristle tips on the
primary inner whorl
of auricu and
bristles, e.g., S. lata (Fig. 6), S. erccta 5. arguta.
A
most some
all species exhibited indication of alternating clavate and
bristles
I
and some
non-cla\'aic bristles exhibited alternating between
(,Fig. 6), short
and
bristles k^ig bristles, e.g. S. u /m i/o/ic], (Fig. 13). Alternation of short and long
m
bi 1st Ics indicated a biseriate pappus even difference was observed
if little tip
two
traits ol the whorls. Variation in the pappus of each species was observed
was
but of limited range; that bristles of a whorl could vary from scores of
is,
0-2 3-4
or lor degree of clavateness, but not to the degree that some had
fruits
only non-clavate bristles while others of the same species had only strongly
Some
species had \'ery clear overlapping of the bases of the primary whorls
ol bristles, eg. S ngulu iFig 10) and odora (Fig. while others
5. 12), hi-
(e.g., 5.
and
iolo) .S uhuijolui) clearly had overlapping of some bases of the pappus
bristles while other bristles on the same fruit did not appear to be overlapping.
Many
other species exhibited only overlapping
slight of the bristle bases
(e.g.,
S.glomerata and multiradiata) random some
or overlapping
S. of bristle bases
but not in a clear primary inner whorl and primary whorl
outer
pattern,
(e.g., S.
Icavenworthii and Some
simplex). species appeared have no overlapping
S. to
bases, S.altissima
e.g. (Fig.
11).
Some much
had
species of Solidago a third, reduced, secondary outer whorl
