Ferns 



233 



LycopodiaceaD), the Selaginellas are popularly regarded as Ferns, and are 

 culturally treated as such. There are over 300 species known, one S. 

 spinosa (or selaginoides) being a native of Britain. The plants are easily 

 recognized by the stems bearing four rows of scalelike leaves two rows 

 of small ones on the upper surface, and two rows of larger ones at the 

 sides one large leaf and one small one arising at each joint. The repro- 

 ductive organs sporangia are borne at the tips of the shoots in angular 

 conical spikes (fig. 316 c). There are two kinds of sporangia "mega- 

 sporangia" and " microsporangia ". Each 

 megasporangium usually contains four large 

 " megaspores " or " macrospores ", and each 

 microsporangium contains a large number of 

 small microspores (fig. 316). The latter are 



A Frond with spore-bearing spikes or cones (c), 

 nat. size. 



Section of Spore-bearing Cone, 

 bowing Megasporangia on left 

 and Microsporangia on right 



Fig. 316. Selaginella incequatyolia 



usually borne in the axils of the upper scale leaves, while the former are 

 in the axils of the lower. The process of fertilization is practically the 

 same as in the Ferns (see p. 213). 



Comparatively few Selaginellas are grown on a large scale for market. 

 They require a close moist atmosphere, and will flourish in a light compost 

 suitable for Ferns generally. Propagation is effected either by cuttings 

 of the stems having rootlets or by spores. Among the smaller-growing 

 kinds worthy of notice are S. apus or apoda, S. ccesia or uncinata, S. 

 Kraussiana (or denticulata), and its varieties aurea and variegata. These 

 grow from 1-3 in. high, and have trailing stems and an ornamental mosslike 



