Bulbophyllum section Monanthes (Blume) Aver., Ident. Guide Vietnamese Orchids (1994) 279
Minute to medium sized epiphytes. Rhizomes creeping, straggling, or erect to pendulous; rhizome bracts thin, glabrous to papillose, caducous but veins thick (sometimes only 1 vein present), often persistent as fibres. Roots sprouting along the entire rhizome or only sprouting near the base, spreading or growing over or alongside the rhizome towards the substrate, glabrous to slightly and locally hirsute. Pseudobulbs conspicuous or small compared to the size of the plant, 1-leafed, with shoots either sprouting from its basal node and free, not fused to the pseudobulb, or at any distance from the basal node because fused to and partly or entirely covered by it. Leaves persistent, thick, veins inconspicuous. Inflorescences sprouting from nodes along the length of the rhizome or near the pseudobulbs only, at a (short) distance above the subtending rhizome bract attachment (in Bulbophyllum aff. microdendron, NGF 39698 observed so far above it that they sprout sub-opposite the next bract), single to densely fasciculate, fascicles sometimes branching (several flowers simultaneously from a single rhizome node); 1-flowered. Peduncle short, not or barely protruding from the subtending rhizome bract, to long, with the top well above the leaves, peduncle bracts 2, (sub-)basal (upper approx. half-way peduncle in Bulbophyllum alabastraceus). Flowers per sympodium branch 1 open at a time; floral bracts tubular; pedicel with the basal node level with the attachment of the floral bract, shorter to little longer than the ovary. Sepals free, or the laterals connate along their lower margin, the laterals usually approx. as long as the median (the laterals up to 22 times as long as the median in Bulbophyllum bicaudatum, Bulbophyllum inauditum; the median 3— 4 times as long as the laterals in Bulbophyllum unicaudatum); 3— 100 mm long, obovate to triangular, rounded to caudate, margins glabrous to ciliate; thin to thick, top thickened or not; 3-veined (5— 7-veined in Bulbophyllum plumula), surface glabrous (hirsute abaxially in e.g. Bulbophyllum inauditum; hirsute adaxially and papillose abaxially in Bulbophyllum unicaudatum). Petals 0.4— 25 mm long, (transversely) elliptic to triangular, retuse to caudate, margins entire or distally erose, glabrous to ciliate; thin 1-veined (3-veined in Bulbophyllum masonii), surface glabrous to hirsute. Lip mobile on a thin ligament, with or without minute, retrorse auricles near the ligament, undivided or 3-lobed with lateral lobes towards the base, 1.1— 15 mm long, elliptic or oblong, through (ob-)ovate to linear, or spathulate or panduriform, margins glabrous to (glandular) ciliate; adaxially without ridges, or often with a median ridge which is often highest near the base of the lip, and often flanked by two shorter ridges or calli proximally (with two [additional] ridges in approx. flexural position in Bulbophyllum fibristectum, Bulbophyllum myolaense), surface glabrous to papillose or hirsute, abaxial surface glabrous (papillose in Bulbophyllum fuscatum, long-hairy in Bulbophyllum fibristectum). Column with rostellum front (deeply) receding in between the stelidia tips, stigma large, without keels inside, proximally protruding or not, or with a tooth, column foot tapering towards its top, free part virtually absent (present but short in Bulbophyllum fibristectum); with or without a callus just short of the ligament. Stelidia shorter to much longer than 1/2 of the length of the column; deltoid to subulate, without a tooth along the upper margin (with a large, triangular tooth in e.g. Bulbophyllum bivalve), with or without a slight, rounded wing along the lower. Anther abaxially with a low or high, usually rounded crest, front not concave, front margin usually drawn out into a small, semi-circular to triangular beak or not. Pollinia 2, or 4 and with the inner less than half as long as the outer (4 of equal length in Bulbophyllum fibristectum); without appendages (a fleshy appendage in Bulbophyllum consimile).
New Guinea: 90 taxa. Altogether 122 provisionally accepted taxa (150 names): India (Darjeeling) and China, Indochina, to Australia and Pacific.
Includes Section Hybochilus, which displays a morphological diversity comparable to section Polyblepharon, but has the lateral sepals free. These can be distinguished from section Oxysepala by the presence of a median ridge on the adaxial side of the lip. After taking off the species with free lateral sepals as a separate series, a combination of two characters each with two states permits distinction of 4 more convenient groups presumably without any phylogenetic meaning:
a (section Hybochilus)
Lateral sepals free.
b Rhizomes creeping to straggling. Lateral sepals fused. Lip with minute, retrorse auricles near the ligament.
c Rhizomes creeping to straggling. Lateral sepals fused. Lip without minute, retrorse auricles near the ligament.
d Rhizomes erect to pendulous. Lateral sepals fused. Lip with minute, retrorse auricles near the ligament.
e Rhizomes erect to pendulous. Lateral sepals fused. Lip without minute, retrorse auricles near the ligament.
The following taxa in this program belong to this Section:
Bulbophyllum quinquelobum var. lancilabium
Bulbophyllum unicaudatum var. xanthosphaerum