MONOCOTYLEDONS. 



297 



,BUD 



ROOTS 



OLD -_ 



TUBER 



The fruit, a capsule, opens by three longitudinal slits ; the 

 seeds are very small (easily dispersed by wind), the embryo 

 is minute and only slightly developed in the ripe seed. 



313. Four species of Orchis, beside O. mascula, are fairly common 

 in Britain. Spotted Orchis (0. maculata) resembles the Early 

 Purple in having spotted leaves and in the general structure of the 

 flower, but the tubers are lobed (Fig. 117), the spike of firs. (May- 

 July) is shorter and denser, the flowers paler purple, the labellum 

 broader and its middle lobe narrow and not lobed, and the spur is 

 shorter than the ovary. Marsh 

 Orchis (0. latifolia) also has lobed 

 tubers and spotted leaves, dense 

 spike, and grows in moist places, 

 but the flrs. are larger and more 

 deeply purple, and the labellum 

 toothed rather than lobed. Green- 

 winged Orchis (O. morio) has 

 rather small unspotted leaves, a 

 globular tuber, sepals green-veined 

 and arching over the two small 

 upper petals so as to form a hood 

 or helmet ; not so common as the 

 preceding three species, and chiefly 

 found in South England. Pyra- 

 midal Orchis (O. pyramidalis) 

 is easily known by its pyramidal 

 spike of small rosy flrs. , which have a long slender spur ; tubers 

 globular, leaves narrow and long. 



314. The Orchid Family (Orchidaceae) contains over 

 400 genera, with 5000 species. Orchids are most abundant 

 in the tropics, and most of the tropical species are epiphytes, 

 while the temperate species are mostly ordinary land-plants, 

 and all are perennial herbs. It would be impossible here to 

 describe the wonderful adaptations shown by tropical Orchids, 

 both in their vegetative organs and their flowers. The student 

 should read Darwin's book on the Fertilisation of Orchids, 

 and if possible visit hot-houses containing these plants, e.g. the 

 Orchid House at Kew. 



Some British Wild Orchids grow by means of a rhizome, but in 

 most species tubers are developed, as in the Early Purple, the bud for 

 next year's growth being formed at the base of the stem and giving 

 rise to a thick tuberous root. Some of the British genera are rare 

 and local in occurrence, especially those found in the South of England 

 and on chalk. 



Fig. 117. Palmate Tuber of an Orchid. 



