Pachystoma
(from pachys, thick, and stoma, a mouth; alluding to the thick lip). SYN. Pachychilus. Including Apaturia and Ipsea. ORD. Orchideae. A genus comprising about ten species of stove, terrestrial orchids, with erect, nodose rhizomes and simple stems; one is tropical African, and the rest are natives of the East Indies and the Malayan Archipelago. Flowers mediocre or rather large, pendulous, in a simple raceme; sepals connivent, the lateral one sometimes very shortly adnate to the base, of the column; petals similar to the posterior sepals, but slightly smaller; lip affixed to, or adnate to the base of, the column, the lateral lobes oblong and erect, the middle one short. Leaves, for the most part, wanting; but the pseudo-bulbs sometimes at length bear two or three leaves. For culture, see Catasetum. The species introduced are described below.
P. speciosum (showy). fl. yellow, showy, usually solitary, sometimes twin, very sweetly scented; sepals nearly 2in. long, oblong, lateral ones connate with the base of the column; petals slightly narrower, obtuse; middle segment of lip oblong, obtuse, lateral ones broad, acute; scape purple. 1ft. to 1 1/2ft. high. Winter. l. twin, sheathing at base, narrow-ensiform. Root succulent. Ceylon. (B. M. 5701, under name of Ipsea speciosa.) P. Thomsonianum (Thomson's).* fl., sepals and petals white, beautifully shining, as if varnished; lip trifld, bright purple; side laciniae and column light greenish, striped or blotched with brown; peduncle long, velvety green, bearing a raceme of two or more large blossoms. Autumn. l. petiolate, oblong-acuminate. Rhizome trailing, bearing roundish, depressed, sulcate pseudo-bulbs. h. 6in. West Tropical Africa, 1879. (B. M. 6471.)