Astragalus sabulonum A. Gray,

Castillón, Eduardo Estrada, Quintanilla, José Ángel Villarreal, Delgado-Salinas, Alfonso & Rebman, Jon P., 2023, The genus Astragalus (Leguminosae: Papilionoideae: Galegeae) in Mexico, Phytotaxa 586 (1), pp. 1921-1935 : 1921-1935

84. Astragalus sabulonum A. Gray, Proc. Amer. Acad. 13: 368. 1878

Type:— USA, Nevada, Southeastern border of Nevada, near the confluence of Muddy River with the Rio Virgen at Santo Thomas , on sandy ridges. 1877, Palmer 110 (holotype: GH 00058916 digital image!, US 00001549!, MO-149287 digital image!, NY 00005687 digital image!, AC 00319843 digital image!, PH 00005540 digital image!, NA 0026156 digital image!) .

Phaca sabulonum (A. Gray) Rydb., Bull. Torrey Bot. Club 40: 47. 1913.

Astragalus virgineus E. Sheld., Contr. U. S. Natl. Herb. 4: 88. 1893.

Phaca arenicola Rydb., N. Amer. Fl. 24(6): 356. 1929.

Phaca lerdoensis Rydb., N. Amer. Fl. 24(6): 356. 1929.

Annual or if perennial, of short duration. Stems up to 26 cm long, erect, diffuse, decumbent, straight or distally in zig-zag, commonly with purple tones, villous to hirsute, trichomes up to 1 mm long. Stipules 1–4 mm long, semiclasping, decurrent, not connate, triangular to deltoid. Leaves 1.5–6.5 cm long, leaflets 5–15, 2–14 mm long, oblong to oblanceolate, basally narrowed, truncate, obtuses or notched apically, bicolored, abaxially clearer, adaxially somewhat glabrate along midvein. Peduncles 1–4 cm long; the racemes 0.5–2.5 cm long, flowers 2–7. Flowers ochroleucous, with purple or lilac tones, or only the veins of the banner purple or purple-lilac, or the banner only purple around the fold area; the calyx 3.3–6.2 × 1.8–2.7 mm, hirsute, trichomes white o rarely with few additional, scattered black trichomes, the tube 1.6–2.4 mm long, the teeth 1.7–3.6 mm long, subulate; the banner 5.2–7.2 × 3.8–5.4 mm, recurved, obovate to suborbicular, basally narrowed, basally ending in a minute claw, apically obtuse to wide notched; the wings 5.7–6.8 × 1.8–2.4 mm, the claw 1.8–2.4 mm long, the blade 4–5.3 mm long, oblique, obovate, somewhat incurved; the keel 5–6.5 × 2–2.3 mm, the claw 2–2.6 mm long, the blade 3–4.2 mm long, distally oblique, obovate. Pod 9–20 × 4–11 mm, sessile, spreading or deflexed, commonly humistrate when fruits ripen, oblique, ovoid, to ovoid-oblong, widened, but not inflated like a bladder, incurved, lunate, basally rounded or narrowed, commonly ventrally sulcate, distally contracted in a triangular beak, dorsally rounded or slightly and openly sulcate, the valves fleshy, thin, turning leathery o stiff-papery, green, turning ochre with age, sometimes with purple or dark-redish spots, hirsute to strigulose, the trichomes fine to dense, white; septum absent; ovules 10–19; seeds 2–2.5 mm long, brown, mitten shape, sometimes with purple tones, shiny.

Distribution:— In Mexico, found only in the northwestern Sonora in the Desierto de Altar (San Luis Río Colorado, Golfo de Santa Clara and La Salina). Also, in Arizona, New Mexico, California, Nevada, and Utah ( USA) ( Fig. 24 ).

Habitat:— Areas near (0.5 km) sandy dunes along the coast; vegetation with stabilized dunes, with psamophilic and halophitic vegetation; desert scrubland with creosote bush; sandy flat above high tidal zone, adjacent to tidal channels; 40– 45 m.

Comments:— In the area of the Desierto de Altar, A. aridus , A. insularis var. harwoodii and A. sabulonum are all found. These species have a similar physiognomy, stems regularly ashy and racemes with few flowers (2–9), however, A. aridus is distinguished from these other by its smaller white with pink or lilac flowers, with its keel 3.6–5 mm long, and the banner almost always shorter than calyx teeth, and ascending, silky-canescent pubescent small pods (1–1.7 × 4.5–7 mm) with few ovules (3–7). The other two species have deflexed flowers and fruitswhen mature. Astragalus insularis var. harwoodii (purple-reddish) and A. sabulonum (ochroleucous, but with purple tints), have longer pods, averaging 13–29 mm, rarely 9–10 mm long, and a larger number of ovules, averaging10–19, rarely 7–9. The difference between these two last species is more subtle, in A. insularis the pubescence of the pod is short, appressed and straight, the trichomes shorter than 0.7 mm long, whereas in A. sabulonum the pubescence is villous, longer than 0.7 mm long, or if less than this size, those are curled or at least incurved. Most of time, peduncles and racemes are longer in A. insularis , up to 7 cm, and up to 6 cm, respectively. So far as we know, A. sabulonum is only distributed in northern Sonora in Mexico but it should be expected also in Baja Califronia.

Specimens examined:— SONORA: 5 March 1992, 6 March 1992 , Ca. 12 airline km ESE of El Golfo de Santa Clara, ca, 0.5 km inland from shore, R. S. Felger 92-188, K. Cliffton ( NY, TEX-LL); 23 March 1993 , Delta del Río Colorado, Sonora, R. S. Felger 92-246, E. Glenn, V. Moretsky, D. Ortiz Reyna ( NY) ; 23 March 1993 , Delta del Río Colorado, Sonora, R. S. Felger 92-246, E. Glenn, V. Moretsky, D. Ortiz Reina ( MEXU, NY, USON) ; 27 March 1905 , Mesa near Inter. Bound . Colorado river Sonora, Mac Dougal 87 ( NY); 27 March 1905 , Mesa near Inter. Bound . Colorado river Sonora, D. MacDougal 87 ( NY); 23 March 1993 , Delta del Río Colorado, Sonora, R. S. Felger 92-246, E. Glenn, V. Moretsky and D. Ortiz ( NY) ; 6 March 1992 , Sonora, R. S. Felger 92-221, K. Cliffton ( CAS, MEXU, NY); 14 March 1993 , Delta del Río Colorado, Sonora, Felger 92-246, E. Glenn, V. Moretsky, D. Ortiz Reina ( MEXU, NY, USON) .

Figures

FIGURE 24. Map showing the distribution of Astragalus regiomontanus, A. rupertii, A. sabulonuum, A. sagitticarpus, and A. sanctorum in Mexico.