Dendrobium unicarinatum

Description Herb, epiphytic, erect. Roots whitish, ca 1 – 2 mm wide, at the base of the plant (axillary roots lacking). Stem erect, to 50 cm long, terete or slightly flattened, covered by the sheath of the oldest leaves, blades remaining only in the upper third of the adult stem. Internodes 25 mm long at the base of the stem. Leaves green, shiny above. Blade 49 × 3 mm. Midrib slightly prominent. Two lateral veins visible, <1 mm from the margin (see discussion of anatomy below). Secondaries prominent, convergent at the apex. Base slightly narrower. Apex rounded or emarginate and asymmetrical. Sheath striated in the upper half and ending by a beak opposite to the lamina and applied on the stem. Inflorescence very short, 1 - flowered. Ovary non-resupinate. Floral buds white, flower white to bright yellow when open, fleshy. Tepals with a red terminal dot. Dorsal sepal triangular, 4.5 mm long, 3 mm wide at the base, with 5 nerves. Lateral sepals triangular-ovate, oblique, ca 4 × 2.4 mm, with 8 nerves. Petals ovate, asymmetrical, ca 4 × 2 mm, with 3 nerves. Lip white, entire, rectangular, ca 4 × 2.8 mm, with 5 – 7 nerves, 3 on the carina and 2 – 4 lateral. Apex triangular, rounded to obtuse. Carina ca 1 mm wide. Column 1.8 mm high and 1.5 mm wide. Fruit globose, ca 6 × 9 mm. Dried seed with transparent testa of 217 × 48 μm, fusiform, with extremity and base slender. Right extremity slightly spiral. Hydrated seed ovate, sacciform. Cells cubic to polygonal, with extremities rounded, ca 48 – 100 × 5 μm, with edges thick, roughly spiral, with smooth cellular walls. Embryo spherical, ca 12 μm in diameter.