340 orchidacb^;. (ORCHIS family.) 



Subclass IL MONOCOTYLEDONOUS or EXOGE- 

 NOUS PLANTS. 



Embryo with one cotyledon. Leaves mostly parallel-veined, 

 alternate, entire,, and sheathing at base. Flowers usually in 

 threes. 



Order 76. OKCHIDACEjE. (Orchis Family.) 



Herbs, distinguished by their perfect irregular flowers, with 6-merous 

 perianth adnate to a 1-celled ovary, with very numerous minute ovules 

 on 3 parietal placentae, and with one or two gynandrous stamens, the 

 pollen cohering in masses. Perianth of 6 divisions in 2 sets; the 3 

 outer, or sepals, mostly petal-like and resembling the 3 inner : one 

 of the inner set is variously modified into what is called a labellum or 

 lip, the other two alone being called petals. Before the lip, in the axis 

 of the flower, is the column, composed of a single stamen (more in 

 Cypripedium) variously coherent with or borne on the style or thick 

 fleshy stigma; the anther 2-celled, each cell containing one or more 

 masses of pollen, pollinia. Stigma a broad glutinous surface (except 

 in Cypripedium). — Perennials, often tuberous, sometimes parasitic, 

 with leaves mostly alternate. Flowers showy and singular in shape, 

 arranged for cross-fertilization by means of insects. 



Tribe I. Anther one, terminal and resting like a lid upon the column, deciduous ; 

 pollen-masses '4, smooth and waxy: leafless, except perhaps a single radical leaf: 

 flowers pedicellate. 



1. Calypso. Scape 1-flowered, from a solid bulb. Lip saccate. Column broadly-winged. 



Pollen-masses sessile on a large square membranaceous gland. 



2. Corallorhiza. Flowers racemose, spurred or gibbous at base. Roots branched, coral- 



line. Lip expanded or concave, crested. Column semiterete. Pollen-masses sessile 

 on a short oblong gland. 

 ?• Aplectrum. Flowers racemose, not spurred nor gibbous. Lip expanded, deeply 

 3-lohed. Column nearly terete. Pollen-masses in distinct pairs, without glands. 

 Rootstocks bearing a solid bulb and a single large green leaf. 



Tribe II. Anther one, connate with the column and persistent upon its face just above 

 the stigma; pollen-masses 2, of coarse grains united by an elastic web, each mass 

 attached at base by a stalk to a viscid gland : stems mostly leafy and flowers spicate 

 or racemose, 



4 Habenaria. Flowers numerous, white or greenish. Lip flat, spurred. Glands 

 exposed. 



Tribe III. Anther one, erect and sessile or nearly so upon the top of the column and 

 more or less covering and declinate upon the back of the stigma, persistent; pollen- 

 masses 2 or 4, of loosely cohering granules, hecoming attached by their upper ends to a 

 viscid gland on the beak of the stigma : without spurs. 

 5. Spira iitlics. Perianth oblique upon the ovary, the sepals and petals connivent : lip 

 oblong, embracing the column, with 2 callosities at base. Flowers 1 to 3-ranked in a 

 twisted spike. Stems leafy 'below. 



