草问荆 cao wen jing

Equisetum umbrosum J. G. F. Meyer ex Willdenow.

Plants medium-sized. Rhizome erect or creeping, blackish brown, nodes and roots with sparse long yellowish brown trichomes or glabrous. Aerial stem annual, dimorphic, fertile and sterile stems appearing simultaneously. Fertile stems straw-colored, 15-25 cm tall, 2-2.5 mm in diam. at middle, branched eventually, 10-14-ridged; ridges glabrous; sheath tubes grayish green, ca. 0.6 cm; internodes 2-3 cm; sheath teeth 10-14, light brown, lanceolate, 4-6 mm, membranous, with shallow grooves abaxially. Fertile stems remaining alive after spores shed. Sterile stems straw-colored or grayish green, 30-60 cm, 2-2.5 mm in diam. at middle, well branched in whorls, unbranched below middle, main stem 14-22-ridged; ridges arc-shaped abaxially, each ridge often with a row of tubercles; internodes 2.2-2.8 cm; sheath tubes long, narrow, ca. 3 mm, lower portion grayish green, upper portion grayish green but with a light brown band; sheath abaxially 2-ridged; sheath teeth 14-22, light brown but with a blackish brown line, lanceolate, membranous, persistent. Lateral branches slender, complanate, with 3 or 4 narrow and tall ridges; ridges glabrous abaxially; sheath teeth not open. Strobilus ellipsoid-terete, 1-2.2 cm, 3-7 mm in diam., apex blunt; stalk prolonged when mature and 1.7-4.5 cm. 2n = 216.

Forest margins, stream banks, roadsides; 500-2800 m. Gansu, Hebei, Heilongjiang, Henan, Hubei, Hunan, Jilin, Nei Mongol, Shaanxi, Shandong, Shanxi, Xinjiang [Japan, Mongolia, Russia; C Asia, Europe, North America].