3 io THE LYCOPODIALES 



The Lycopodiales are largely tropical, though a small number 

 of forms are of common occurrence in temperate regions. The 

 stems are erect or creeping and rather small, but owing to their 



FIG. 236. A common club moss fern, Lycopodium annotinum, with 

 creeping stem and erect branches covered with small moss-like leaves : 

 s } strobilus ; r, roots. H. O. Hanson. 



prolonged growth and extensive branching they often form con- 

 spicuous and attractive colonies. The tissues of the stem do 

 not materially differ from those of the common fern, though the 

 vascular bundles are centrally placed and often appear as radiat- 

 ing plates (Fig. 237). The work performed by the leaves, .as 

 in the Equisetales, is usually of two kinds, namely, photosynthe- 

 sis by the green foliage leaves and spore production by the leaves 

 that usually form strobili at the tips of certain branches. But a 

 single sporangium is associated with each of these sporophylls 

 (Fig. 239). 



