32 LYCOPODIUM [CH. 



the male cells are provided with two cilia except in Isoetes 

 which has multiciliate antherozoids like those of the ferns. 

 The existing Lycopods, though widely distributed, never 

 grow in sufficiently dense masses to the exclusion of other 

 plants to form a conspicuous feature in the vegetation of a 

 country. The inconspicuous r61e which they play among the 

 plant-associations of the present era affords a striking contrast 

 to the abundance of the arborescent species in the Palaeozoic 

 forests of the northern hemisphere. 



Lycopodiaceae. Lycopodium, represented by nearly 100 

 species, forms a constituent of most floras : epiphytic species 

 predominate in tropical regions, while others flourish on the 

 mountains and moorlands of Britain and in other extra- tropical 

 countries. For the most part Lycopodium exhibits a preference 

 for a moist climate and appears to be well adapted to habitats 

 where the amount of sunlight is relatively small and the 

 conditions of life unfavourable for dense vegetation. Mountains 

 and islands constantly recur as situations from which species 

 have been recorded. Some species are essentially swamp- 

 plants, e.g. Lycopodium inundatum, a British species, and 

 L. cruentum from the marshes of Sierra Nevada. A variety 

 of the American species, L. alopecuroides (var. aquaticum) 

 affords an instance of a submerged form, which has been 

 collected from an altitude of 12 — 14,000 ft. on the Andes and 

 Himalayas. It is noteworthy that a considerable variety of 

 habitats is represented within the limits of the genus and that 

 many species are sufficiently hardy to exist in circumstances 

 which would be intolerable to the majority of flowering plants'. 



The British species frequently spoken of as Club Mosses, 

 include Lycopodium Selago, L. annotinium, L. clavatuvi, L. al- 

 pinum, and L. inundatum. 



Selaginellaceae. The species of Selaginella, over 300 in 

 number, are widely spread in tropical and subtropical forests, 

 growing on the ground with trailing, suberect or erect stems 

 climbing over taller and stouter plants or as pendulous epiphytes 

 on forest trees. 



1 See Baker (87) A. 



