Psorothamnus

Taxonomy

Psorothamnus P.A. Rydberg N. Amer. Fl. 24: 45. 25 Apr 1919.

Subfamily: Faboideae.
Phylogenetic Number: 3.6.06.
Tribe: Amorpheae.
Species Studied - Species in Genus: 7 studied; 9 in genus.

Description

Fruit: A legumelegume:
usually dry, dehiscent fruit derived from a single carpel that opens along two longitudinal sutures
; unilocular; 0.2–1 cm long; 0.36–0.6 cm wide; 0.36–0.6 cm thick; 2–9 times longer than wide; with deciduous androecial sheath; with deciduous corolla; with persistent calyx; with calyx longer than fruit, or shorter than fruit; without orifice formed by curving of fruit or fruit segments; straight; not plicate; not twisted; symmetrical, or asymmetrical; with 1 straight and 1 curved suture; widest near middle or D-shaped; not inflated; compressed; with beak; straight; with solid beak the same color and texture as fruit; short tapered at apex; aligned with longitudinal axis of fruit to oblique with longitudinal axis of fruit; short tapered at base; aligned with longitudinal axis of fruit; with the apex and base uniform in texture; coriaceous; seed chambers externally visible; seed chambers with the raised seed chambers not torulose; margin not constricted; margin without sulcus; margin plain; wing(s) absent; nonstipitate; indehiscent. Replum invisible. Epicarp dull; monochrome (with glossy reddish-brown glandular dots); reddish brown; with surface texture uniform; glabrous, or pubescent and indurate; with hairs erect; with 1 type of pubescence; puberulent; with pubescence gray; with pubescence uniformly distributed; with simple hairs; pliable; with hair bases plain; glandular; with glandular dots; without spines; not smooth; with elevated features; not veined; not tuberculate; shagreen; not exfoliating; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp absent. Endocarp present; visible; dull; opaque; monochrome; tan; smooth; without adhering pieces of testa; nonseptate; chartaceous; not exfoliating; remaining fused to epicarp; without wings; entire. Seed(s) 1(–7) (-2 in P. kingii (S. Watson) R.C. Barneby or 3–7 in "one extralimital species" Barneby (1977)); length parallel with fruit length; neither overlapping nor touching; in 1 series. Funiculus of 1 length only; straight. Aril absent.

Seed: 4.2–6 mm long; 3–4 mm wide; 2–3 mm thick; not overgrown; not angular; asymmetrical; D-shaped; compressed; with visible radicle and cotyledon lobes; without external groove between radicle and cotyledon lobes; without hilar sinus; without umbo on seed faces; without medial ridge on each face. Cuticle not exfoliating; not inflated; not wrinkled. Testa present; without pieces of adhering epicarp; not adhering to endocarp; free from endocarp; dull; not modified by a bloom; colored; monochrome, or mottled (faintly); with frequent mottles; red; with red overlay; glabrous; smooth; coriaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Raphe faintly visible, or not visible; from hilum through lens to base of seed and terminating; not bifurcating; color of testa, or lighter than testa. Hilum present; visible; with faboid split; with the lips of the faboid split the same color as the rest of the hilum; punctiform; between cotyledon and radicle lobe; recessed; not within corona, halo, or rim. Lens discernible, or not discernible; with margins curved; circular; not in groove of raphe; adjacent to hilum; 0.5 mm from hilum; mounded; dissimilar color from testa; darker than testa; black (-brown), or brown; not within corona, halo, or rim. Endosperm present; thin; not pluglike and not resembling tip of radicle; covering entire embryo; adnate to testa. Cotyledons smooth; both outer faces convex; both the same thickness; both more or less of equal length; not folded; margin entire 180 degrees from base of radicle; similar at apex; partially concealing radicle; notched at radicle, or split over radicle; without lobes, or with lobes; with lobes not touching; with the interface division terminating at base of radicle; without margins recessed; yellow; inner face flat; glabrous on inner face. Embryonic axis deflexed; parallel to length of seed, or oblique to length of seed; without a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; linear; lobe tip curved; deflexed and parallel to cotyledon width; centered between cotyledons; less than 1/2 length of cotyledons. Plumule rudimentary; glabrous.

Distribution

Southwestern United States and northwestern Mexico.

New World; southwestern United States to Mexico (northwestern).

Tribal Notes

Tribe Amorpheae

Traditionally this tribe has been called Amorpheae. Reveal (1997) reported that the name Daleeae was published before the name Amorpheae. Following the International Code of Botanical Nomenclature (Greuter et al., 1994), the oldest name for a taxon must be used, so Reveal suggested that this tribe should called Daleeae. In 1999 Reveal (1999) reversed himself, so that the tribe remains the Amorpheae.