Ranunculus subrigidus W.B. Drew, Rhodora

Wiegleb, Gerhard, Bobrov, Alexander A. & Zalewska-Gałosz, Joanna, 2017, A taxonomic account of Ranunculus section Batrachium (Ranunculaceae), Phytotaxa 319 (1), pp. 1-55 : 37

25. Ranunculus subrigidus W.B. Drew, Rhodora 38: 39 (1936).

≡ Ranunculus circinatus Sibth. var. subrigidus (W.B. Drew) L.D. Benson, Amer. Midl. Naturalist 40: 240 (1948).

≡ Batrachium subrigidum (W.B. Drew) Ritchie, Canad. J. Bot. 34: 300 (1956).

≡ Ranunculus aquatilis L. var. subrigidus (W.B. Drew) Breitung, Amer. Midl. Naturalist 58: 32 (1957).

≡ Batrachium circinatum (Sibth.) Spach subsp. subrigidum (W.B. Drew) Á. & D. Löve, Bot. Not. 128: 512 (1976).

Type: CANADA. Quebec: Gaspé County, York River, 29 July 1905, E. F. Williams, J. F. Collins and M. L. Fernald s.n. ( GH).

– Batrachium foeniculaceum auct. sin., non (Gilib.) V.I. Krecz., Fl. URSS 7: 338 (1937).

Description

Winter- or summer green perennial, hydrophyte; aquatic state with capillary leaves only (myriophyllid), terrestrial state not seen. Shoots up to 100 cm long, internodes of the middle part of the shoot longer or equal to adjacent leaf, hairy in upper part, light green. Laminar leaves absent. Intermediate leaves absent. Capillary leaves present, alternate, 10–25 mm long, suborbicular to obconical, green, pubescent, segments subrigid to rigid, partly clasping to divergent, middle part equal to the lateral ones, length between first and second bifurcation 0.5–2 mm, number of the lamina divisions 3–5, number of final segments 60–80; sessile or with petioles 1–5 mm long, rarely up to 10 mm long. Stipules 1/2 to 2/3 adnate to the petiole, apex of free part rounded, hairy. Peduncles 30–50 mm long, often recurved, glabrous. Sepals 5, 3–4 mm long, elliptic, yellow-green to purplish, spreading. Petals 5(–7), 7–10 mm long, obovate, white with large yellow claw, contiguous during anthesis. Nectar pits 1 per petal, pyriform. Stamens 10–20. Carpels 20–50(–80), 1.5–1.7 mm long, obovate, hairy, style terminal to subterminal, 0.2–0.5 mm long, persistent. Receptacles subglobose, pubescent.—Chromosome number. 2n = 16.