PTERIDOPHYTA 219 



in the tropics. Phylloglossum has a single species confined to Aiistraha, 

 Tasmania, and New Zealand. Fossil forms known as Lycopodites have 

 been found in Carboniferous and later formations. 



Sporophyte. The sporophyte of Lycopodium consists of a slender stem, 

 generally branched, and bearing roots and numerous small leaves. Most 

 of the species are terrestrial plants either with erect stems or, more com- 

 monly, with elongated, trailing or subterranean stems giving rise to 



Fig. 174. Median longitudinal section through the stem tip of Lycopodium reflexum, show- 

 ing the apical meristem and developing leaves, X 100. 



upright branches (Figs. 173A, 179, and 180). Many of the tropical spe- 

 cies are epiphytes with erect or pendent stems (Fig. 1735). The terres- 

 trial species grow close to the ground, few exceeding 30 cm. in height. 

 Numerous roots penetrate the soil. Generally both the roots and stems 

 branch dichotomously, but in some species the branching of the stem is 

 apparently monopodial, the branches arising laterally from a true main 

 axis. The leaves are small and often scale-like, simple, entire, and 

 densely cover the branches. They are generally borne in spiral arrange- 

 ment. Growth of the root and stem takes place by means of an apical 

 meristem, no apical cell being present (Fig. 174). 



Although Phylloglossum is much simpler than Lycopodium, it is gen- 

 erally regarded, not as a primitive form, but as one reduced from more 

 highly developed ancestors. The sporophyte is only 3 to 5 cm. high and 



