水冠草 shui guan cao

Argostemma iriomotense Masamune; A. taiwanense S. S. Ying.

Herbs, to 30 cm tall, sometimes branched; stems erect, puberulent or villosulous to glabrescent. Leaves opposite, slightly to markedly anisophyllous, in larger leaf of a pair petiole 0.5-3 cm, villosulous to glabrescent; blade drying membranous, ovate, lanceolate, or elliptic-oblong, 25-100 × 12-30 mm, adaxially glabrous or sparsely hirsute or pilose, abaxially pilosulous or villosulous along principal veins and glabrous on lamina, base cuneate to obtuse, margin entire and glabrous, apex acute to weakly acuminate; secondary veins 7 or 8 pairs; stipules persistent, oblong-elliptic or ovate, 3-7 mm, glabrescent, obtuse. Inflorescences cymose, 1-6-flowered, strigillose or villosulous to glabrescent; peduncles 1-2.5 cm; bracts triangular and 1-3 mm or resembling reduced leaves and stipules; pedicels 5-20 mm. Calyx villous, villosulous, or hirsute; hypanthium portion subglobose, ca. 1.5 mm; lobes 5, triangular, ca. 1.5 mm. Corolla white, rotate, glabrous; tube ca. 1.5 mm; lobes 5, narrowly lanceolate, ca. 7 mm, marginally densely ciliate. Stamens 5; anthers coherent, 5.5-7 mm, dehiscent by linear slits. Capsules cupuliform, 2-3 mm, leathery, densely hirsute or villosulous, with persistent calyx limb to 3 mm. Fl. Mar-Apr, fr. Jul.

Shady and moist streamsides; below 100-500 m. Taiwan [Japan (Ryukyu Islands), Philippines].

This species appears to vary widely in size of the plants, leaf size, and pubescence; it has sometimes been characterized (e.g., FRPS 71(1): 180-182. 1999) based only on larger plants, as described in the protologue. The two synonymous names listed here were not included in FRPS but were cited in Fl. Taiwan (ed. 2, 4: 247. 1998).