460 ORCHIDEiE 



and often gorgeously-coloured flowers are the only conspicuous 

 part of the plant. They have greyish-green aerial roots which 

 are furnished with a peculiar superficial structure adapted to 

 the absorption of atmospheric moisture, and clustered, elliptical 

 branches known as pseudobulbs, from the summit of which spring 

 a few green, leathery leaves, and slender peduncles which hardly 

 seem capable of producing the numerous blossoms, beautiful in 

 form and colour, which they are destined shortly to bear. The 

 British species have mostly rounded or palmate root-tubers, two 

 or more glossy sheathing leaves, and a simple spike or raceme 

 of flowers, which are in most cases red, pink, white, or greenish. 

 They have 3 sepals, often petaloid ; and 3 petals, the lowest 

 unlike the rest, and frequently spurred. The structure of this 

 lower lip of the corolla, or labellum, is often most singular, 

 resembling some insect or presenting a fantastic caricature of 

 some more important member of the animal kingdom. " There 

 is," says Lindley, " scarcely a common reptile or insect to which 

 some of them have not been likened." The stamens are united 

 with the style into a central column, only one, or rarely two, of 

 them producing pollen, which, though sometimes powdery, is com- 

 monly united into 2 club-shaped masses, or pollinia, one in each 

 chamber of the anther. The ovary is inferior, and often so 

 twisted as to invert the flower, and so long as to be mistaken 

 for a pedicel ; it is 1 -chambered, with 3 parietal placentas. The 

 stigma is a viscid hollow in front of the column ; and the fruit 

 a 3-valved, many-seeded capsule. The floral structure of the 

 Order is, in spite of the varied form of the labellum, very uniform, 

 and, in most species, clearly adapted to secure insect-pollination. 

 The flowers have, in many cases, powerful odours and secrete 

 honey ; but in the spurred forms this honey is within the tissue 

 of the spur, instead of being, as in other groups, in the cavity 

 of the spur. The insect seeking honey is thus delayed by the 

 necessity of boring for it, and, meanwhile the stickiness of a 

 gland, or retinaculum, at the base of the pollinium has time to set 

 on the insect's head. The whole pollinium is thus removed from 

 the anther, and, in some cases, while being borne to some other 

 blossom, it bends, so as more effectually to strike against the 

 stigma. As only a part of the pollinium is torn off by the 

 viscidity of the stigma, the insect may thus pollinate many 

 blossoms. The spur of Angrcecum sesquipeddle , a native of 

 Madagascar, is no less than 9 inches long ; but, as foretold by 

 Darwin, a hawk-moth has been found in the same island with 

 a proboscis of even greater length. In some species the labellum 

 is irritable. In Caledna nigrita, for instance, the column is a 



