6. Limnophila rugosa (Roth) Merrill, Interpr. Herb. Amboin. 466. 1917.
大叶石龙尾 da ye shi long wei
Herpestis rugosa Roth, Nov. Pl. Sp. 290. 1821.
Perennials, 10-50 cm tall. Rhizomes transverse. Stems 1 to few, fascicled, erect or ascending, usually unbranched, glabrous. Leaves opposite; petiole 1-2 cm, narrowly winged; leaf blade ovate, rhomboid-elliptic, or elliptic, 3-9 X 1-5 cm, abaxially hispidulous along veins, adaxially glabrous or sparsely hispidulous, margin crenate; veins pinnate, ca. 10 on each side of midrib, abaxially raised. Peduncle 0.2-3 cm; bracts subspatulate-oblong, with flattened membranous glands, margin entire or apically undulate-toothed and ciliate. Flowers axillary, solitary, sessile, usually appearing capitate. Bracteoles absent. Calyx 6-8 mm, without raised veins in fruit or with 5 raised veins and flattened membranous glands, margin ciliate. Corolla purple-red to blue, to 1.6 cm. Style slender, apically cylindric, pubescent, with a membranous auricle on both sides. Capsule pale brown, ovoid, ca. 5 mm. Fl. and fr. Aug-Nov.
Adjacent to water, mountain valleys, grassland; below 900 m. Anhui, Fujian, Guangdong, Guangxi, Hunan, Taiwan, Yunnan [Bhutan, India, Indonesia, Japan (Ryukyu Islands), Laos, Malaysia, Myanmar, Nepal, Philippines, Sikkim, Thailand, Vietnam; Pacific Islands].