Table Of ContentPROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
112(1):216-219. 1999.
Two new subtribes, Stokesiinae and Pacourininae, of the Vernonieae
(Asteraceae)
Harold Robinson
Department of Botany, National Museum of Natural History, Smithsonian Institution,
Washington, D.C. 20560, U.S.A.
—
Abstract. New subtribes Stokesiinae and Pacourininae are established in
the Vernonieae (Asteraceae) for the Southeastern United States genus Stokesia
and the South American genus Pacourina
Revisions of the Vernonieae by the au- (Figs. 1-4). The genus has a chromosome
thor have until recently involved mostly number that differs from most other Ver-
Western Hemisphere members (Robinson nonieae, especially other genera from the
A =
1996). In the absence of studies of Old Western Hemisphere. first count of n
World members of the tribe, among which 9 (Jones, 1968) has been corrected by a se-
relatives might have been discovered, the ries of six subsequent counts of n = 7
monotypic Western Hemisphere genera Sto- (Jones 1974). Almost all other New World
kesia UHer. and Pacourina Aubl. were left Vernonieae have n = 16 or 17. Most Old
unplaced as to subtribe. More recent studies World Vernonieae have n = 9 or 10.
of Old World Vernonieae by the author
have made it clear that Stokesia and Pa- Stokesiinae H.Rob., subtribus nov.
courina are most closely related to other
Western Hemisphere genera, but that they Type: Stokesia UHer., Sertum Angl. 27.
are deserving of separate subtribal status. 1789.
m
The new subtribes are described below. Plantae herbaceae perennes ad 0.5 al-
The genus Stokesia has long been noted tae, sparce pilosae, pilis longis simplicibus
for its mostly liguliform corollas, resem- non septatis. Folia plerumque rosulata al-
bling those of the tribe Lactuceae, Fitchia tema base anguste petioliformia in nodis
Hook.f. of the Heliantheae, and some Mu- vaginata. Inflorescentiae pauce capitatae
tisieae such as Hyaloseris Griseb. (Espinar laxe cymosae. Capitula pedunculata; brac-
1973). The tribal position has sometimes teae involucri 40-50 in seriebus 3-4, brac-
been questioned, but placement has usually teae exteriores in appendicibus longe foli-
been in its correct position in the tribe Ver- iformes margine spinosae, bracteae inter-
&
nonieae (Bentham Hooker 1873, Hoff- iores angustiores in apicibus setiferae. Flo-
mann 1890-1894). The genus contains a res 60-70 homogami; corollae azurae vel
single species, and has been promoted as a albae plerumque late liguliformes in limbis
possible crop plant useful as a source for 5-lobatae, corollae centrales ca. 3 actino-
&
epoxy resins (Gunn White 1974). The morphae; thecae antherarum base rotunda-
plant is also widely cultivated as an orna- tae, cellulis endothecialibus distincte linea-
A
mental. drawing has been provided by tis, lineis in partibus longitudinalibus cet-
Gunn and White (1974), and a color pho- erum variabiliter arcuatis; appendices api-
tograph can be seen in Rickett (1967). The cales antherarum breves glabrae in
pollen of the genus has a rather weak per- parietibus cellularum tenues; basi stylorum
forated tectum and a unique lophate pattern non noduliferi; rami stylorum glandulo-
with trisected colpi meeting at the poles punctati, papillis aciculiformibus argutis.
.
VOLUME 112, NUMBER 1 217
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n
H
i^^^W
^^^^^^^om^^g^'g
m
^
pW^k
) HIS^^H
fW
^^^^^^^v* ^^^ mi^ ^^^^H
E
1
3
4
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Figs. 1-4. Stokesia laevis (Hill) Greene, Knobloch 1426 (US), Mississippi. 1. Polar view, line = 20 |jim. 2.
Colpar view, line = 20 fxm. 3, 4. Detailed views of muri with baculae and perforated tectum. 3. line = 3.8 fjim.
=
4. line 1.76 |xm.
Achenia 3-4-angulata plerumque prope bas- to the Southeastern United States in south-
em glandulo-punctata, cellulis subsuperfi- em South Carolina, Georgia, Alabama and
cialibus porosis fibriformibus, raphidis sub- Mississippi, western Florida and eastern
nullis minutis breviter oblongis; squamae Louisiana.
pappi 4 aut 5 subulatae perfacile deciduae Pacourina is a singularly distinctive
mm
8-9 longae. Grana pollinis triporata, la- emergent aquatic plant of tropical America.
cunis colpi rhomboideis, muds minute The inflorescence, with heads sessile in a
crenulatis (Figs. 1-4). Numerus chromoso- series of leaf axils, is reminiscent of the
matum n = 1 Lepidaploa Group in the subtribe Vemoni-
The single species in the subtribe is Sto- nae. The sclerified apical anther appendage,
kesia laevis (Hill) Greene, which is native however, is totally foreign to that group and
218 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
Figs. 5, 6. Pacourina edulis Aubl., Killip and Smith 14576 (US), Colombia. 5. Whole grain, line = 15 ixm.
2. Closer view showing lacuna with pore and lack of micropunctations on muri, line = 6.7 ixm.
is extreme for even the Piptocarphinae and epaleacea; flores ca. 50 in capitulo; corollae
Lychnophorinae. Triporate, psilolophate purpureae, lobis distaliter valde scleroideis;
pollen is known otherwise in the tribe Ver- thecae anterharum base dentate appendicu-
nonieae only in the Paleotropical subtribe latae; appendices apicales antherarum gla-
Erlangeinae, but the pollen of Pacourina is brae valde scleroideae; basi stylorum leniter
larger than pollen in any members of that latiores, pilis stylorum acicularibus. Ach-
group, and the inflorescence and anther ap-
enia 10-costata suberose corticata in sulcis
pendages are totally different. Thus, the idioblastifera; setae pappi breves multiser-
combination of characteristics precludes
iatae deciduae, squamellis persistentibus.
placement in any presently existing subtribe
Grana poUinis triporata psilolophata emi-
of the Vemonieae. Closest relationships of
cropunctata (Figs. 5, 6).
the new subtribe are not known, but they
The single species in the subtribe in Pa-
are presumed to be Neotropical. The dis-
courina edulis Aubl. of Central America
tinctive nature of the plant may derive to
and tropical South America. The species is
considerable extent from is aquatic special-
well illustrated in Nash and Williams (1976,
ization.
fig. 7, p. 461).
Pacourininae H.Rob., subtribus nov.
Acknowledgments
Type: Pacourina Aubl., Hist. PI. Guiane
2:800. 1775.
Plantae camosae aquaticae, folia simpli- The SEM photographs were made by Su-
cia altema valde dentata. Inflorescentiae se- sann Braden of the National Museum of
SEM
riate cymosae, bracteis foliiformibus; capit- Natural History Laboratory using a
ula sessilia axillaria solitaria late campan- Hitachi S-570. Prints were prepared by
ulata homogama; bracteae involucri ca. 50 Sherry Pittam, previously of the Depart-
latae virides et margine albae; receptacula ment of Botany.
—
VOLUME NUMBER
112, 1 219
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