Nature and Habits of Orchids. 95 



It is not alone in the form of the flowers that the orchidaceous plants 

 differ from other members of the floral world : the whole structure of the 

 plant is peculiar. The roots are of four kinds : First, Annual fibres, simple 

 or branched, of a succulent nature, incapable of extension, and burrowing 

 under ground, as in the genus Orchis. Secondly, Annual fleshy tubercles, 

 round or oblong, simple or divided, as in the various species of the same 

 genus : they are always combined with the first, and appear to be intended 

 as receptacles for matter fit for the nourishment of the plant. Thirdly, 

 Fleshy, simple, or branched perennial bodies, much entangled, tortuous, or 

 irregular in form, as in Corallorhiza, &c.; or nearly simple, and resembling 

 tubers. Fourthly, Perennial round shoots, simple, or a little branched, 

 capable of extension, protruded from the stem into the air, adapted to ad- 

 hering to other bodies, and formed of a woody or vascular axis, covered 

 with cellular tissue, of which the subcutaneous layer is often green, and 

 composed of large reticulated cells : the stem is often (as in some terres- 

 trial species) merely a growing point surrounded by scales, and constituting 

 a leaf-bud when at rest, but eventually growing into a secondary stem 01 

 branch, on which the leaves and flowers are developed. In other cases 

 the growing point becomes perennial, thickens, is scarred with the remains 

 of leaves which once grew upon it, and assumes the state of a short round 

 or ovate perennial stem or pseudo-bulb. 



Or, again, the rhizoma, instead of having pseudo-bulbs, forms short stems, 

 which are terminated by one or more leaves. The leaves are very uncer- 

 tain in their appearance : usually they are sheathing at the base, and mem- 

 branous ; but in some species they are hard-stalked, articulated with the 

 stem, and have no trace of a sheath. Frequently they are leathery and 

 veinless ; as frequently they are membranous and strongly ribbed ; and 

 both these conditions may occur in the same genus, as in Cyprepediian. 



The peculiarities of the floral leaves and organs will more properly be 

 noticed in treating of the classification of orchids. Sufiice it to say, that 

 the flowers are constructed irregularly upon the ternary type, and consist of 

 three exterior and three interior pieces, of which the exterior are usually 

 nearly equal, and less brightly colored than the interior. 



On account of the peculiarities of growth and structure, so unlike other 



