Xylobium
(from xylon, wood, and bios, life; in allusion to the substance on which the plants grow). ORD. Orchideae. A genus comprising about sixteen species of stove, epiphytal, tropical American Orchids, closely allied to Maxillaria. Flowers racemose, very shortly pedicellate; sepals erect, at length somewhat spreading, the lateral ones broader than the upper one, adnate at base to the foot of the column, forming a chin; petals similar to the upper sepal, but smaller; lip subarticulated with the foot of the column, sessile or contracted and incumbent at base, at length erect, the lateral lobes erect, clothing the erect, semi-terete column, the middle one short, broad, spreading; scapes at the bases of the pseudo-bulbs, erect, simple. Leaves ample or elongated, plicate-veined, contracted into the petioles. Stems short, many-sheathed, mostly thickened into a one or two-leaved, fleshy pseudo-bulb. The best-known species are here described. For culture, see Maxillaria (under which the species were formerly classed).
X. concavum (concave-lipped). fl. pale yellow; lateral sepals falcate, acuminate; petals half as large as the sepals; lip almost truncate, concave, bluntly three-lobed, the middle lobe somewhat fleshy and tuberculated at the edge, rose-veined, with a long, narrow ridge in the middle, three-lobed at the point. l. twin, three-ribbed, shining, narrowed into the petioles. Pseudo-bulbs oblong, deeply furrowed. h. 9in. Guatemala, 1844. SYN. Maxillaria concava (L. & P. F. G. ii., p. 53).
X. decolor (discoloured). fl., sepals and petals sulphur-coloured, the former ovate-oblong, obtuse, spreading, the latter half as large, connivent; lip whitish, obsoletely three-lobed, obtuse, hooded, with five elevated, parallel calli; scapes radical, many-flowered. l. solitary, oblong-lanceolate, acuminate at both ends, 1ft. to 1 1/4ft. long. Pseudo-bulbs oblong, compressed. h. 1ft. Jamaica, 1830. SYN. Maxillaria decolor (B. M. 3981; B. R. 1549).
X. elongatum (elongated). fl. in a dense, oblong raceme; sepals and petals pale, linear, acuminate; lip purplish-brown, warted, ovate-oblong, very fleshy; scapes erect, two-sheathed. l. lanceolate, three-ribbed, about twice as long as the elongated, cylindrical pseudo-bulbs. h. 1ft. Central America, 1847. SYN. Maxillaria elongata (L. & P. F. G. iii., p. 69.) X. foveatum (foveate). fl. of a pale, uniform straw-colour, faintly scented; sepals and petals linear-oblong; lip three-lobed at apex, the middle lobe rounded, fleshy, excavated. l. lanceolate, undulated, thrice as long as the raceme. h. 1ft. Demerara, 1839. Allied to X. squalens. SYN. Maxillaria foveata.
X. pallidiflorum (pale-flowered). fl. pedicellate; sepals and petals pale sulphur-coloured, one-ribbed, the lower sepals broadly falcate; lip whitish at back, reflexed above, somewhat truncate-emarginate at apex; racemes erect, three to seven-flowered. l. oblong, acuminate, glabrous, 8in. to 10in. long, three-ribbed, arcuate-recurved, attenuated into the petioles. Pseudobulbs densely aggregated, cylindrical, 6in. to 7in. long. h. 1ft. Venezuela, 1826. SYN. Maxillaria pallidiflora (B. M. 2806).
X. squalens (squalid). fl. pale, dingy yellowish-flesh-coloured, numerous, in a dense, thyrsiform raceme; two of the petals and the three-lobed lip streaked with purple, the side lobe of the lip deep purple; scape 4in. to 6in. high, brown-scaly. l. two to a pseudo-bulb, 8in. to 12in. long, tapering into footstalks, strongly five-ribbed. Pseudo-bulbs several, oblong, dark green, sheathed with brown scales. Brazil, 1828. SYNS. Maxillaria squalens (B. M. 2955), Dendrobium squalens (B. R. 732).