Psorothamnus fremontii

PLANT : Shrubs, glabrous to appressed pubescent, to 1.5 m tall; glands inconspicuous. LEAVES : pinnately compound; leaflets 3-5, linear to 6 CANOTIA Vol. 7 2011 oblong, 3-25 mm long, 1-2 mm wide, strigose. FLOWERS : in a lax, open raceme; calyx teeth 1.8-3.2 mm long, generally shorter than tube. FRUIT : 7-10 mm long, glabrous, densely covered with elongate glands in rows. NOTES : Sandy or rocky soils derived from granite and sandstone of washes, banks, and debris fans: w Coconino, Mohave, w Yavapai cos. (Fig. 2A); 350-1000 m (1200-3200 ft); (Mar) Apr-May; CA, NV, UT. Two varieties have been recognized (Barneby 1977) and both were noted to occur in Arizona. Psorothamnus fremontii var. fremontii was separated from P. fremontii var. attenuatus Barneby based upon leaflet shape (narrowly obovate to linear-elliptic in var. fremontii vs. narrowly linear in var. attenuatus) and leaflet size (3-15 mm long × 1.5-4.0 mm wide in var. fremontii vs. 5-25 mm long × 1.0-1.2mm wide in var. attenuatus). While the varieties as described by Barneby (1977) have overlapping ranges, var. fremontii generally occurs on sedimentary formations of limestone, and sandstone, and var. attenuatus occurs on volcanic and granitic bedrock. Two Arizona specimens (A. Phillips s.n., MNA and C. Schaack 1464, ASC) have narrowly linear leaflets but the leaflets are short, suggesting that they are diminutive leaves. Further collecting in Arizona is needed before these varieties can be recognized. REFERENCES : Rhodes, Suzanne, June Beasley and Tina Ayers. 2011. Fabaceae. CANOTIA 7: 1-13.