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PLANT MORPHOLOGY 



2. LYCOPODIINAE' 



The lycopods, numbering nearly 950 species, are an ancient group 

 represented in our modern flora by only four surviving genera. They 

 were abundant in the Devonian but reached their greatest display during 

 the Carboniferous (Fig. 258), when some were trees 30 m. tall. Today 

 all lycopods are herbaceous, generally growing close to the ground. They 

 are characterized by leaves that are mostly small, simple, and spirally 

 arranged and by sporangia that are always solitary, adaxial, and uniloc- 

 ular. There are four orders, the Lycopodiales, Selaginellales, Lepidoden- 

 drales, and Isoetales. Of these, the third is extinct. 



Fig. 173. Two tropical species of Lycopodium from Costa Rica, about one-third natural 

 size. A, Lycopodium cernuum, a terrestrial species with upright stems and nodding cones; 

 B, Lycopodium tubulosurn, a pendent epiphytic species with loosely organized cones at the 

 ends of the branches. 



1. Lycopodiales 



Only two living genera belong to this order. Lycopodium, with 180 

 species, is widely distributed throughout the world but is most abundant 

 • Also called Lycopsida. 



