Description from Flora of China
Lycopodium aristatum Humboldt & Bonpland ex Willdenow var. robustius Greville & Hooker; L. clavatum var. asiaticum Ching; L. clavatum var. robustius (Greville & Hooker) Nakai.
Stolons subterranean, slender and creeping, 1 or 2 times forked, green, with sparse entire leaves; lateral branches erect, 20-25 cm tall, 3-5 times forked, sparse, flattened (young branches terete), stem together with leaves 9-12 mm in diam. Leaves spirally arranged, dense, angled upward, lanceolate, 4-6 × ca. 1 mm, leathery, with transparent hairs, midrib visible on both surfaces, base cuneate, decurrent, sessile, margin entire, apex acuminate. Strobili 2(or 3) together on a peduncle, peduncle up to 12 cm, bracts of peduncle spirally arranged, sparse, herbaceous, narrowly lanceolate; strobili erect, terete, 3.5-4.5 cm × ca. 4 mm, subsessile or with short, equally long pedicels; sporophyll broadly ovate, ca. 1.5 × 1.3 mm, papery, margin membranous, erose, apex acute, with short acute tip. Sporangia slightly exposed.
Lycopodium clavatum differs from L. japonicum in its fertile branches each bearing 2(or 3) strobili with equal pedicels.
Coniferous forests, among dry moss; 700-1800 m. Heilongjiang, Jilin, Liaoning, Nei Mongol [Japan, Korea; North and South America].