Equisetum hyemale subsp. affine

(Engelmann) Calder & Roy L. Taylor

Canad. J. Bot. 43: 1387. 1965.

Basionym: Equisetum robustum var. affine Engelmann Amer. J. Sci. Arts 46: 88. 1844
Synonyms: Equisetum hyemale var. affine (Engelmann) A.A. Eaton Equisetum hyemale var. californicum J.Milde Equisetum hyemale var. pseudohyemale (Farwell) C.V. Morton Equisetum hyemale var. robustum (A.Braun) A.A. Eaton Equisetum prealtum
Treatment appears in FNA Volume 2.

Aerial stems persisting more than a year, unbranched, 18–220 cm; lines of stomates single; ridges 14–50. Sheaths when mature dark-girdled, brown to gray above girdle, squarish in face view, 4.5–17 × 3.5–18 mm; teeth 14–50, articulate and promptly shed or persistent. Cone apex pointed; spores green, spheric. 2n =216.

Phenology: Cones maturing in summer, old stems sometimes developing branches with cones in spring.
Habitat: Moist roadsides, riverbanks, lakeshores, woodlands
Elevation: 0–3000 m


V2 735-distribution-map.gif

Alta., B.C., Man., N.B., Nfld. and Labr. (Nfld.), N.W.T., N.S., Ont., P.E.I., Que., Sask., Yukon, Ala., Alaska, Ariz., Ark., Calif., Colo., Conn., Del., D.C., Fla., Ga., Idaho, Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Mont., Nebr., Nev., N.H., N.J., N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Tex., Utah, Vt., Va., Wash., W.Va., Wis., Wyo., Mexico, Central America in Guatemala.


In southern and central to western regions plants tend to be taller and have more persistent teeth (Equisetum robustum, E. prealtum); in the Far West they often have bituberculate ridges (E. hyemale var. californicum). Equisetum hyemale subsp. hyemale is found in Europe and Asia to northwestern China in Xinjiang.

Subspecies affine is found throughout subarctic Alaska, including the Aleutian Islands.

Selected References


Lower Taxa

Richard L. Hauke +
(Engelmann) Calder & Roy L. Taylor +
Equisetum robustum var. affine +
Alta. +, B.C. +, Man. +, N.B. +, Nfld. and Labr. (Nfld.) +, N.W.T. +, N.S. +, Ont. +, P.E.I. +, Que. +, Sask. +, Yukon +, Ala. +, Alaska +, Ariz. +, Ark. +, Calif. +, Colo. +, Conn. +, Del. +, D.C. +, Fla. +, Ga. +, Idaho +, Ill. +, Ind. +, Iowa +, Kans. +, Ky. +, La. +, Maine +, Md. +, Mass. +, Mich. +, Minn. +, Miss. +, Mo. +, Mont. +, Nebr. +, Nev. +, N.H. +, N.J. +, N.Mex. +, N.Y. +, N.C. +, N.Dak. +, Ohio +, Okla. +, Oreg. +, Pa. +, R.I. +, S.C. +, S.Dak. +, Tenn. +, Tex. +, Utah +, Vt. +, Va. +, Wash. +, W.Va. +, Wis. +, Wyo. +, Mexico +  and Central America in Guatemala. +
0–3000 m +
Moist roadsides, riverbanks, lakeshores, woodlands +
Cones maturing in summer, old stems sometimes developing branches with cones in spring. +
Canad. J. Bot. +
Illustrated +
Equisetum hyemale var. affine +, Equisetum hyemale var. californicum +, Equisetum hyemale var. pseudohyemale +, Equisetum hyemale var. robustum +  and Equisetum prealtum +
Equisetum hyemale subsp. affine +
Equisetum hyemale +
subspecies +