Lycopodium clavatum L.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - 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 × 0.5–0.8 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.