33. Pattalias S. Watson, Proc. Amer. Acad. Arts. 24: 60. 1889.
Milkvine, swallow-wort [Greek pattalias, pricket or stake, alluding to stout, conical beak surmounting stigma in P. palmeri, the type species]
Mark Fishbein
Vines, herbaceous [woody at base]; latex white. Stems twining vigorously, unarmed, glabrous. Leaves persistent, opposite, sessile; stipular colleters interpetiolar; laminar colleters apparently absent. Inflorescences extra-axillary, solitary at nodes, umbelliform, pedunculate. Flowers: calycine colleters present; corolla green or cream, often brown- or purple-tinged, campanulate, aestivation contort-dextrorse; corolline corona absent; androecium and gynoecium united into a gynostegium adnate to corolla tube; gynostegial corona of 1 whorl of 5 laminar, somewhat fleshy segments opposite stamens, connate only at very base, united to column at base of anthers; anthers adnate to style, locules 2; pollen in each theca massed into a rigid, vertically oriented pollinium, pollinia lacrimiform, joined from adjacent anthers by translators to a common corpusculum and together forming a pollinarium. Fruits follicles, typically solitary, variously oriented, brown, narrowly fusiform, terete, smooth, glabrous. Seeds winged, not beaked, ovate, flattened, comose, not arillate.
Species 2 or 3 (1 in the flora): se United States, n, se Mexico, West Indies, Central America (Belize).
Formerly included in a broadly circumscribed, polyphyletic Cynanchum, especially following the influential revision of North American milkweed genera by R. E. Woodson Jr. (1941), Pattalias is placed close to or within Funastrum in phylogenetic analyses (S. Liede and A. Täuber 2002). Further study may support submersion in Funastrum, but the morphological distinctiveness of Pattalias and absence of definitive phylogenetic evidence warrant maintenance of this genus (M. Fishbein and W. D. Stevens 2005). Fishbein and Stevens misinterpreted the priority of names pertaining to this genus and placed the species of Pattalias in Seutera Reichenbach, but this latter name is illegitimate (Fishbein 2017).
