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PROCEEDINGS 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 p n H i^^^W ^^^^^^^om^^g^'g m ^ pW^k ) HIS^^H fW ^^^^^^^v* ^^^ mi^ ^^^^H E 1 3 4 ^^H « 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 Literature Cited . 1974. V—ernonieae (Compositae) chromosome numbers. Bulletin of the Torrey Botanical Bentham, G., & J. D. Hooker. 1873. Compositae. Club 101:31-34. Genera Plantarum. Vol. 2(1):163-533. Reeve & & Nash, D. L., L. O. Williams. 1976. Flora of Gua- Co., London. — temala. Fieldiana: Botany 24(12):1-603. Espinar, L. A. 1973. Revision del genero Hyalosehs — Rickett, H. W. 1967. Wild flowers ofthe United States, (Compositae). Kurtziana 7:195-21 1. Gunn, C. R., & G. A. White. 1974. Stokesia laevis: the southeastern states. 2(2):601, pi. 224. Mc- — Graw-Hill, New York. taxonomy and economic value. Economic Botany 28:130-135. Robinson, H. 1996. The status ofgeneric and subtribal Hoffmann, O. 1890-94. Compositae 4(5):87-387. In revisions in the Vernonieae. Pp 511-526 in D. A. Engler & K. Prantl, (eds.).—Die Natiirlichen J. N. Hind &—H. J. Beentje, eds., Compositae: Pflanzenfamilien. Leipzig. Systematics. Proceedings of the International Jones, S. B. 1968. Chromosome numbers—in South- Compositae Conference, Kew, 1994. (D. J. N. eastern United States Compositae, I. Bulletin Hind, Editor-in-Chief)- Vol. 1, Royal Botanic of the Torrey Botanical Club 95:393-395. Gardens, Kew.