Horizontal stems on substrate surface. Upright shoots clustered, 0.6--1.2 cm diam., dominant main shoot with 3--6 branches mostly in lower 1/2. Lateral branchlets few and like upright shoots; annual bud constrictions abrupt, branchlets mostly spreading. Leaves spreading, often somewhat ascending in distal 1/3 of branches, medium green, linear, 4--6 X 0.4--0.8 mm; margins entire; apex with narrow hair tip 2.5--4 mm. Peduncles 3.5--12.5 cm, with remote pseudowhorls of appressed leaves, loosely branched into 2--5 alternate stalks, 0.5--0.8 cm. Strobili 2--5 on alternate stalks (if double, usually with stalks 5--8 mm), 15--25 X 3--6 mm. Sporophylls 1.5--2.5 mm, apex abruptly reduced to hair tip. 2 n = 68. Fields and woods; 100--1800 m; St. Pierre and Miquelon; B.C., Man., N.B., Nfld., N.S., Ont., P.E.I., Que., Sask.; Alaska, Calif., Conn., Ga., Idaho, Ill., Ind., Ky., Maine, Md., Mass., Mich., Minn., Mont., N.H., N.J., N.Y., N.C., Ohio, Oreg., Pa., R.I., Tenn., Vt., Va., Wash., W.Va., Wis.; Mexico; West Indies; Central America; South America; Europe; Asia; Africa; Pacific Islands. Plants found in eastern North America have been called Lycopodium clavatum var. clavatum ; those in the western part of the range, which have been called L . clavatum var. integrifolium Goldie, are distinguished by early shedding of the characteristic hairs on the leaf tips. Lycopodium dendroideum group
Horizontal stems superficial, elongate, arching and rooting at intervals, 2-3 mm thick, not dorsiventral, the lvs curved upwards; erect stems branched, to 2.5 dm; lvs mostly 10-ranked, uniform, linear-subulate, 4-7 נ0.5-0.8 mm, slightly or scarcely toothed, attenuate to a hyaline hair-like tip 2-3 mm; cones 1.5-11 cm, 3-7 mm thick, 1-6 on remotely bracteate peduncles 1.5-15 cm; sporophylls yellowish, broad-based, abruptly acuminate, with scarious erose margins; sporangia reniform, ca 1.5 mm wide; spores 28-36 microns in diameter, the sides convex, the commissural and outer faces angular-reticulate, the commissures not in furrows; 2n=68. Open dry woods and rocky places in acid soil; circumboreal, s. in e. U.S. to N.C., W.Va., Mich., and Io.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.