Description from Flora of China
Plants small to medium-sized. Rhizome erect, creeping, or ascending, blackish brown, nodes and roots with few to numerous long yellowish brown trichomes or glabrous. Aerial stem perennial, monomorphic, green, 20-60 cm tall, 1-7 mm in diam. at middle, lower portion of main stem often branched, tufted; internodes 2-10 cm; young whorled branches conspicuous or inconspicuous; main stem 5-20-ridged, ridges arc-shaped abaxially, with a row of tubercles or small light brown cross grains; sheath tubes narrow, up to 1 cm, lower portion grayish green, upper portion usually grayish brown; sheath teeth 5-22, grayish white to light or blackish brown, deltoid, base flat or arc-shaped, margin (sometimes upper part) membranous, caducous or persistent, with conspicuous or inconspicuous stomatal bands. Lateral branches hard, terete, 5-12-ridged; ridge glabrous or with 1 row of tubercles or small pale cross grains; sheath teeth 5-10, upper portion brown, lanceolate, leathery but membranous at margin, usually persistent. Strobilus shortly clavate or ellipsoid, 0.5-2.5 cm, 0.4-0.7 cm in diam. at middle, apex with small acute tip, sessile. 2n = 216.
Reviewer Ralf Knapp notes that both subspecies of Equisetum ramosissimum are present in Taiwan but that the exact distribution (both regional and elevational) is currently insufficiently known. The highest known population in Taiwan is ca. 1650 m for subsp. ramosissimum, which on average appears to grow at higher elevations than subsp. debile.
Forests, forest margins, under bushes, meadows, banks of rivers and streams; sea level to 3600 m. Anhui, Chongqing, Fujian, Gansu, Guangdong, Guangxi, Guizhou, Hainan, Hebei, Heilongjiang, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Jilin, Liaoning, Nei Mongol, Ningxia, Qinghai, Shaanxi, Shandong, Shanxi, Sichuan, Taiwan, Xinjiang, Xizang, Yunnan, Zhejiang [Afghanistan, Bangladesh, Bhutan, India, Indonesia, Japan, Kashmir, Korea, Laos, Malaysia, Mongolia, Myanmar, Nepal, New Guinea, Pakistan, Philippines, Russia, Singapore, Sri Lanka, Thailand, Vietnam; Africa, C and SW Asia, Europe, S Pacific islands; introduced in North America].