XCVIII. ORCHIDACEJE 
489 
XCVIII. ORCHIDACE^ 
Terrestrial, usually succulent, scapose herbs ; roots fibrous or 
tuberous, annually producing erect flowering-stems. Leaves simple, 
entire, sometimes reduced to scales, alternate or crowded, base 
usually sheathing. Flowers of peculiar shape and structure, in a 
terminal, spike-hke raceme. Perianth superior, usually fleshy ; 
segments 6, in two series, free or variously combined ; the three 
outer or sepals nearly alike, usually green ; the three inner or 
petals dissimilar, coloured, the two side ones similar, the third or lip 
very differently shaped and sometimes extended downwards in a 
hollow spur. Functional stamen one, except in Cypripedium, united 
with the style in a fleshy column ; neither stamen nor style is 
differentiated or externally visible. Anther one, except in Cypri- 
pedium, situated on the column, cells 2, except in Oreorchis, con- 
tiguous or widely separated , parallel or divergent ; pollen, except 
in Gypripedium, cohering in 1, 2 or 4 pairs of minute, waxy or 
powdery, usually club-shaped masses or pollinia, either free or 
attached at the base or by a thread-like stalk or caudicle to a 
viscid gland naked or sometimes covered by a small pouch. Ovary 
1 -celled, usually linear and twisted, placed below the flower ; 
stigma, except in Cypripedium, a small, more or less concave 
portion of the face of the column, or, as in most species of 
Habenaria, consisting of two linear, projecting arms. Capsule 
cylindrical or ovoid, generally ribbed; seeds minute, very numerous. 
In Gypripedium there are two functional stamens ; the pollen 
is granular and glutinous ; and the stigma is borne on a very 
short style. — One of the largest Natural Orders, generally spread 
over nearly the whole globe ; most numerous in subtropical 
climates but extending into the arctic regions nearly to the limits 
of vegetation ; rare in. remote islands. 
Most of the tropical Orchids are epiphytes, growing on trees ; some grow on 
rocks ; but those in Simla and its neighbourhood are almost all terrestrial. 
The fact that the peculiar structure of the flowers of Orchids renders them 
in most cases entirely dependent on insect agency for the transference of the 
pollen to the stigma has been known in a general way for more than a hundred 
years, but it was not until 1862, when Darwin published his famous work on 
The various Contrivances by which Orchids are fertilised ( pollenised ) by 
Insects , that our knowledge of the subject became in any degree either accurate 
or complete. It is not within the scope of this book to repeat Darwin’s in- 
genious explanations of the complex contrivances exhibited in these flowers, 
but the action of the essential parts may, perhaps, with advantage, be briefly 
summarised. 
The honey, secreted in the spur or sometimes on the surface of the lip, 
offers an attractive food for insects, and the lip serves as a convenient resting 
place. The viscid drop or gland, placed directly in the path of an insect seek- 
ing to obtain the honey, glues the pollinia so firmly to its head that, when the 
insect flies off, they are dragged out of the anther, and are carried in such a 
