无瘤木贼 wu liu mu zei

Equisetum robustum A. Braun var. affine Engelmann, Amer. J. Sci. Arts 46: 88. 1844; E. praealtum Rafinesque; E. robustum A. Braun; E. affine (Engelmann) Rydberg; E. hyemale var. affine (Engelmann) A. A. Eaton; E. hyemale var. komarovii (Iljin) W. Wang; E. hyemale var. robustum (A. Braun) A. A. Eaton; E. komarovii Iljin; E. praealtum var. affine (Engelmann) M. Broun; Hippochaete hyemalis f. affinis (Engelmann) Satou; H. hyemalis var. affinis (Engelmann) S. X. Li & J. Z. Wang; H. praealta (Rafinesque) Farwell; H. praealta (Rafinesque) Farwell var. affinis (Engelmann) Farwell.

Plants large. Rhizome creeping or erect, blackish brown, nodes and roots with long yellowish brown trichomes. Aerial stem perennial, monomorphic, green, up to 1.5 m tall, 5-10 mm in diam. at middle, not branched or base with few erect lateral branches; internodes 6-9 cm. Aerial stem 16-22-ridged; ridges arc-shaped abaxially or nearly rectangular, without conspicuous tubercles; sheath 0.8-1.1 cm, blackish brown or both distal portion and base with a blackish brown band, or only distal portion with a blackish brown band; sheath teeth 16-22, lanceolate, small, 0.3-0.5 cm, teeth of distal portion light brown, membranous, aristate, caducous, teeth of lower portion blackish brown, thinly leathery, abaxially 3-ridged at base, persistent or falling off early with sheath. Strobilus ovate, 1.1-1.6 cm, 0.4-0.7 cm in diam., apex with small acute tip, sessile.

Forests; 700-1000 m. Heilongjiang [Russia (Far East); Central America (Guatemala, Mexico), North America].