Podostemum flagelliforme (Tulasne & Weddell) C. T. Philbrick & A.Novelo, comb. nov. Devillea flagellifonnis Tulasne & Weddell, Ann. Sci. Nat., Bot., ser. 3.11:107. 1849. Oserya flagellifonn is (Tulasne & Weddell) Warming in Engler, Nat. Pflanzenfam., ed. 2, 18a: 64. 1930.-TYPE: BRAZIL. Tocantins: Rio Tocantin near Sao Joao, Weddell 2367 (holotype: P!; isotypes: C! L!). Plant description: Roots 0.1-0.3 (0.2) mm wide. Stems monomorphic, 0.2-2 (1) cm long. Leaves peti olate, upright, arising in a 180° distichous arrangement, simple (occasional at base of stem) or 1-6 (2) times dichotomously divided, 8.5-25 (16.5) mm long; divisions arising in a 2-dimensional manner; ultimate leaf divisions 0.5-5.2 (2.2) mm long, 0.1-0.3 (0.1) mm wide, linear, flattened, apices acute, with a faint vein or vein absent; petioles 0.5-2 (1.1) mm long, round to elliptical in cross section; leaf bases symmetrical, attached per pendicular to stem axis; stipules composed of a symmetrical boat-shaped extension of the leaf base, 1-1.9 (I.I) mm long, entire, caducous, absent from leaves 1-2 nodes back from the apex. Flowers 1-2 (1) per stem; spathella 1.6-3.1 (2.5) mm long, 0.7-1.2 (1) mm wide,smoothtominutely papillate,apexroundedorwithanipple;tepals3,linearorspat ulate, straight, apex blunt or acute; lateral tepals 0.3-0.7 (0.4) mm long; 1 staminal tepal arising from the back (dorsal) side of the stamen filament, 0.3-0.5 (0.4) mm long; stamen 1, filaments 0.7-1.1 (0.8) mm long prior to and during anthesis; anthers 0.5-0.8 (0.6)mm long, 0.5-0.8 (0.6) mm wide; pollen monads 20-22.5 (22) µm long, 15-18 (16) µm wide; ovary 0.8-1.2 (0.9) mm long, 0.6-1.1 (0.9) mm wide; stigmas entire, 0.1-0.2 (0.1) mm long prior to anthesis, during anthesis to 0.2 mm; pedicels 0.4-1 (0.9) mm long prior to anthesis, during anthesis to 0.7-1.6 (0.9) mm. Capsules 1-1.2 (1.1) mm long, 0.9-1 (0.9) mm wide, smooth (lacking ribs); pedicels in fruit 4-6.2 (5.2) mm long; seeds not known.
Podostemum flagelliforme is known only from the type collection. Tulasne (1849) reported the type from "Brasilia tropica media." In an unpublished manuscript in P (Weddell, Catalogue du plantes recueillies dans I'Amerique du Sud, 1843-47) the locality is listed as Rio Tocantins, near Sao Joao, in the vicinity of Porto Imperiale, Goias (the region now the state of Tocantins) ,Brazil.
The single stamen and monad pollen distinguish P. flagelliforme from all other species of Podostemum. The short blunt stigmas are also notable; other species in the genus, as well as most other species of Podostemaceae in the New World, have linear elongate stigmas. The entire, boat-shaped stipule and dichotomously divided leaves are similar to those of P. ceratophyllum. The latter species, however, has dyad pollen, two stamens, and ribbed capsules. Podostemum flagelliforme has ribless (smooth) capsules, as do P. ovatum, P. saldanhanum, P. scaturiginum, and P. weddellianum.
Podostemum flagelliforme was originally described as Devillea flagelliformis Tul. & Wedd., in Tulasne (1849, p. 107). Some workers (e.g., Baillon 1886; Warming 1891; En gler 1930) placed this species in the genus Oserya, but our phylogenetic studies indicate that it is monophyletic with species of Podostemum.