In this article we will discuss about the external features of lycopodium.
1. Plant body is sporophytic and the sporophyte is divisible into roots, stem and leaves (Fig. 224).
2. The genus is divisible into two subgenera, i.e., Urostachya and Rhopalostachya. In sub-genus Urostachya, the plant body is erect or pendant, rarely branched, with rarely organized strobili, and the sporophylls are entire and their length is similar with the foliage leaves, e.g., L.selago, L. phlegmaria, etc.
But in sub-genus Rhopalostachya, the plant body is creeping or trailing, well-branched showing dichotomy, with well-organized strobili, and the sporophylls with toothed margins and their length is quite dissimilar with the foliage leaves, e.g., L. cernuum, L. clavatum, L. inundatum, etc.
3. Roots are adventitious, dichotomously branched and small.
4. Stem is erect or pendant in sub-genus Urostachya, while it is prostrate with upright branches in subgenus Rhopalostachya.
5. The branching of the stem is partly monopodial and partly dichotomous.
6. The stem is thickly covered with many leaves.
7. Leaves are eligulate, simple, small, sessile, usually lanceolate in outline with broad base. Each leaf contains a single unbranched midvein (Fig. 225).
8. Leaves are arranged (Fig. 226) spirally in L.clavatum and L. annotinum, in pairs in L. alpinum, and in whorls in L.cernuum.
9. In L.volubile the leaves are heterophyllous.
10. Leaves contain many equally distributed stomata.
