Desmanthus acuminatus Benth., sharppod bundleflower. Subshrub, winter–deciduous, not spinescent, not rosetted, several–stemmed at base, with spreading to decumbent principal branches, in range mostly < 30 cm tall; shoots with compound cauline leaves, secondary leaflets folding together when touched (thigmotropic), short–hairy without glandular hairs.
Stems 5–ridged and 5–sided, to 3 mm diameter, with 3 ridges descending from each leaf, swollen at nodes, aging striped.
Leaves helically alternate, even–2–pinnately compound with 4—6 pairs of primary leaflets and 9—17 pairs of secondary leaflets, petiolate with pulvinus, with stipules; stipules 2, attached to leaf base below pulvinus, basal portion with several short, reflexed and fringed basal lobes, a triangular base and threadlike upper portion to 7 mm long, upper portion light strawberry–colored, conspicuously short–hairy, deciduous; petiole pulvinus to 3 mm long, short–hairy, above pulvinus ± 4–sided, to 5 mm long, short–hairy, at top with extrafloral nectary cup next to the lowest pair of primary leaflets, 0.3—0.4 mm diameter, green with rose rim or crimson, outer surface puberulent; rachis ± 4–ridged, with pairs primary leaflets to 4 mm apart; stipel subtending primary leaflet absent; primary leaflet petiolule pulvinus 1 mm long, often purple–red, above pulvinus 0.5—1 mm long, short–hairy; rachilla to 16 mm long + extension to 3.5 mm long, pairs closely spaced (to 1.3 mm apart), flat on upper side, lower side short–hirsute and glaucous; secondary petiolule pulvinus 0.25 mm long, green; blades of secondary leaflets oblong–lanceolate to oblong, 2.3—4.8 × 0.7—1.2 mm, the lowest pair 1/2 of other leaflets, asymmetric at base, entire and short–ciliate on margins, acute at tip, 1–veined at base not raised on surfaces, midrib closer to leading edge.
Inflorescence headlike spike, axillary, subspheroid in bud later with a mass of twisted and overlapping exserted stamens, (6—)10—16–flowered, flowers helically alternate, on most spikes the lowest flowers (to midpoint) staminate, above midpoint flowers bisexual, bracteate, short–hairy; peduncle pulvinus at base, 5–ridged, to 16 mm long increasing 2× in fruit, short–hairy; rachis < 1 mm long, glabrous; bractlet subtending flower < 1 mm long, stalked with upper portion diamond–shaped, fringed, crisped, veiny and short–hairy on back.
Staminate flower radial, variable = spreading crooked filaments; calyx 5–lobed, 1 mm long; tube bell–shaped, colorless with 5 faint greenish veins; tobes (teeth) unequal, ± deltate, 0.3 mm long, often purple–red; petals 5, narrowly spatulate, ± 2 × 0.4 mm, white with green above midpoint and narrow colorless margins; stamens 10, free; filaments never straight, 6.5—8 × 0.1 mm, white; anthers dorsifixed, dithecal, 0.5—0.65 mm long, light yellow, longitudinally dehiscent; pollen light yellow; pistil absent.
Bisexual flower radial, variable = spreading crooked filaments; calyx 5–lobed, 2.3—2.5 mm long; tube narrowly funnel–shaped, 2 mm long, colorless with 5 faint greenish veins; tobes (teeth) unequal, ± deltate, 0.2—0.5 mm long, often rose and with red point at tip, the largest lobe rounded on back; petals 5, oblanceolate, ± 3.5 × 0.7 mm, white with green above midpoint; stamens 10, free; filaments never straight, 6.5—8 × 0.1 mm, white; anthers dorsifixed, dithecal, 0.5—0.65 mm long, light yellow, longitudinally dehiscent; pollen light yellow; pistil 1, 6.5—8 mm long, the uppermost flower with the longest pistil and stamens, stalked (stipe), stalk 0.25 mm long, greenish; ovary superior, narrowly oblong, ca. 2 mm long, green, glabrous, 1–chambered with < 20 ovules attached to upper side; style cylindric, 4.5—6 mm long, white; stigma terminal, recessed in funnel–shaped tip.
Fruit pod (legume), dehiscent by 2 valves, to 17–seeded, linear and slightly curved strongly flattened side–to–side slightly bulging at seeds, 26—45 × 3.5 mm, valves dark brown, acute–acuminate at tip, seeds somewhat overlapping; stalk stout and short, < 1 × 1 mm.
Seed ± ovate to trapezoidal in outline and compressed side–to–side, 3—4.3 × 2—3 mm, brown to reddish brown and not mottled, smooth.
A. C. Gibson