Dalea reverchoni

  • Title

    Dalea reverchoni

  • Authors

    Rupert C. Barneby

  • Scientific Name

    Dalea reverchonii (S.Watson) Shinners

  • Description

    49. Dalea reverchoni (Watson) Shinners

    (Plate LIX)

    Herbaceous from a tough woody taproot, 1.5-2 dm tall, the few, simple or distally 1-branched, densely leafy stems decumbent, prominently ribbed, glandless, rather densely pilosulous with fine incurved or sinuous hairs up to 0.15-0.25 mm long, the aloysia-scented foliage green and glabrous, the leaflets smooth above, punctate beneath; leaf-spurs 0.4-1 mm long; stipules narrowly subulate to linear-attenuate, 1-3.5 mm long, becoming dry, recurved, brittle, brown or livid; intrapetiolular glands minute or 0; post-petiolular glands small but prominent, blunt; leaves mostly subsessile, the primary cauline ones (all subtending leaf-spurs or branchlets) 2-3 cm long, with 3 or 4 pairs of linear-oblong or -oblanceolate, obtuse, bluntly gland-mucronulate, loosely inrolled or marginally elevated, thick-textured, dorsally carinate leaflets up to 5-12 mm long, the terminal one longest, either sessile or short-stalked beyond the last pair; peduncles up to 1 cm long; spikes loose, the flowers (pressed) falling into 2-3 ranks to expose the densely villous-tomentulose axis, without petals 8-10 mm diam, becoming 1.5-5 cm long; bracts deciduous narrowly ovate, ± 2.5 mm long, densely pilosulous dorsally; calyx 4.2-4.6 mm long, densely silky-pilosulous or -tomentulose from base upward with fine lustrous subappressed hairs up to 0.25 mm long, the pentagonally turbinate tube 1.9-2.1 mm long, not recessed behind banner, obtusely angled by the ribs leading to the sinuses, the ribs leading to the teeth more slender and scarcely prominent, the broad intervals either hyaline or densely castaneous-flecked, glandless, the teeth of nearly equal length, the 3 dorsal ones lance-acuminate, 2.1-2.5mm long, 0-0.5 mm longer than tube, the ventral pair triangular-acuminate, scarcely shorter, all firmly herbaceous or livid, pilosulous within, spreading in age; petals all vivid magenta-purple, glandless; banner 4.3-4.6 mm long, the claw 2-2.5 mm, the scoop-shaped, apically hooded, obtuse or subacute blade 2.1-2.3 mm long, 1.82 mm wide, broadly cuneate to subtruncate (not cordate) at base; epistemonous petals 3.1-3.6 mm long, the claw 0.7-0.8 mm, the oblong, concave, obtuse or subacute blades cuneate at base, 2.6-3 mm long, 1.1-1.3 mm wide; androecium 6.1-7.2 mm long, the column 2.5-3.2 mm, the magenta-purple filaments 3.3-4 mm long, the anthers orange; pod 3.1-3.5 mm long, in profile plumply half-obovate, the short ventral suture straight or slightly concave, the dorsal one strongly convex, the prow prominent, thickened, the valves thinly papery but not hyaline at base, papery, pilosulous and minutely gland-sprinkled distally; seed not seen. — Collections: 3 (i).

    Dry stony hillsides on limestone, rare and local on northern outlying spurs of Edwards Plateau in n.-centr. Texas (Hood and Parker counties).—Flowering May- June, September-October. —Material: Texas. Hood: Comanche Peak, Reverchon 1273 (NY, US). Parker: 3 mi s.-w. of Springtown, Barneby 13,529 (CAS, IA, NY SMU).

    Dalea reverchoni (Watson) Shinners, Field & Lab. 17: 84. 1949, based on Petalostemon reverchoni (Julien Reverchon, 1834-1905) Wats., Proc. Amer. Acad. 21: 449. 1885. — "On the rocky top of Comanche Peak, in western Texas, J. Reverchon, June, 1882 (n. 36)." — Holotypus, so labelled (Wemple, 1970, p. 76), GH! isotypus (fragm.), NY!- Kuhnistera reverchoni (Wats.) A. Hell., Bull. Torrey Club 23: 124. 1896.

    A strongly marked species, distinguished from the marginally sympatric D. tenuis by the short, pilosulous stem contrasting with green leaflets, these seven or nine (not three or five) in the primary cauline leaves, and by the open spike of pentagonal, antrorsely pilosulous calyces. The loose flower-spike distinguishes the species equally from D. purpurea or D. compacta. The allopatric D. tenuifolia, ranging over the high plains of the Texas Panhandle and northwestward into adjoining states, has a relatively loose spike, but once again differs in fewer leaflets (3 or 5), stems pilose only at base and not throughout, and long-pilose calyces subtended by broad, obovate bracts. Only D. gattingeri resembles D. reverchoni in leaflet-number, and this has an indistinctly ribbed, not bluntly pentagonal calyx.

    Until recently D. reverchoni was known only from the type-locality, where it was collected first in 1882, and once again in 1900 by Eggert (MO, acc. Wemple, not seen). Wemple (1970, p. 76) thought it might well be extinct, but I had the extraordinary luck to happen on a flourishing colony of plants, sparsely flowering, perhaps unseasonably, in October, 1964. The species must be expected to turn up elsewhere around the northern fringes of Edwards Plateau.