Australian Tropical Rainforest Plants - Online edition
Rhaphidospora cavernarum (F.Muell.) R.M.Barker
Barker, R.M. (1986) Journal of the Adelaide Botanic Gardens 9: 232.
Perennial tuberous herb to shrub, straggling or upright to about 1 m tall. Stems constricted above leaf nodes, longitudinally ribbed, clothed in white eglandular tortuous hairs.
Leaves variable, lower leaves larger and on long petioles usually thinly winged to the base, leaves gradually reducing in size up the stems, and upper leaves on short petioles or +/- sessile, with white eglandular hairs. Leaf blades ovate to rhomboid, about 3-88 mm x 2.5-38 mm, petioles about 0-26 mm long though usually thinly winged to base, white hairs on both surfaces, denser on the under surface and on veins. Leaf base attenuate on large leaves to cuneate, rounded and cordate as leaves become smaller; leaf apex acuminate to acute; margins crenate to smooth. Cigar-shaped cystoliths (deposits of calcium carbonate) visible with a lens on both surfaces of the leaf blade but more obscure beneath. Midrib with a double ridge on the upper surface at least towards the base of the leaf blade. Lateral veins raised on the upper surface of the leaf blade. Pith rather copious.
Inflorescences axillary and terminal, mostly a simple 2-3-flowered dichotomously branched panicle (a dichasium). Peduncles with glandular and eglandular hairs. Bracts and bracteoles ca. 1.2-1.8 mm long. Calyx with 5 linear lobes, with glandular and eglandular hairs. Corolla tube 5-6 mm long, upper lip 2.7-3.5 mm long, lower lip with median lobe 4 mm long, lateral lobes 5.5 mm long; corolla outside hairy, inside glabrous. Stamens 2, filaments glabrous or with a few hairs in a line, anthers lopsided and staggered, the lower anther locule with a basal appendage to ca. ? 0.4-0.5 mm long. Ovary seated on a conspicuous disk, hairy. Style long and slender, stigma small and terminal.
Capsules +/- clavate, 11-14 mm long, lower half constricted into narrow stalk, widened above into seed-bearing portion ca. 4.5 mm wide, hairy on the outer surface. Seeds light brown, flattened, ca. 2.8 mm diameter, up to four per capsule; testa clothed in pale brown spines. Radicle curved along the side of the cotyledons.
Cotyledons broad, somewhat falcate or oblique, about 11-12 x 8-9 mm. Stems, petioles and the upper and lower surfaces of the first pair of true leaves hairy. At the tenth leaf stage: leaf blade very attenuate at the base and acuminate at the apex, margin crenate, sinuate or slightly toothed. Lateral veins about 3-5 on each side of the midrib. Stem distinctly swollen just above each pair of leaves. Stem densely clothed in short white hairs. Seed germination time 213 days.
Description adapted from Barker (1996) J.Adel.Bot.Gard. Vol. 17: 151, and specimens at the Australian Tropical Herbarium.