MONOCOTYLEDONS 269 



trunks and branches of trees ; and are dispersed by means 

 of their very minute and light seeds. Some are saprophytes 

 (PP- 355-7) an d grow on humus, but most of the species in 

 temperate regions are terrestrial. They are largely culti- 

 vated for the brilliant colours and often curious and extra- 

 ordinary forms of their flowers, which are the most highly 

 specialized of the Monocotyledons (Fig. 137, p. 199). To 

 some of them characteristic names have been given. 

 The more common and interesting British species are : 



Early Purple Orchis (Orchis mascula), Spotted Orchis (O. macu- 

 lata), Butterfly Orchis (Habenaria spp.), Bee Orchis (Ophrys apifera), 

 Spider Orchids (O. arachnites and aranifera), Fly Orchis (O.muscifera), 

 Lady's Tresses (Spiranthes spp.), Coral-root (Corallorrhiza innata), 

 Lady's Slipper (Cypripedium Calceolns), ~fte\\ebox'\r).es>(Epipactis spp.), 

 Tway Blade (Lister a ovata). 



The class Monocotyledons contains about 24,000 species. 

 The simpler and more primitive forms have no perianth and 

 the parts of the flowers are spirally arranged and indefinite, 

 e. g. Pond-weeds (Potamogeton). The flowers of Grasses are 

 protected by bracts, have few stamens and carpels, and are 

 pollinated by the wind. The Water Plantain and Flowering 

 Rush have a double perianth, the parts being in two whorls 

 of three each. The flowers of the higher forms are cyclic 

 and have often five trimerous whorls, e. g. Lily and Bluebell. 

 The most highly developed forms have epigynous and 

 irregular flowers, with one or two stamens, e. g. Orchids. 



