Astragalus scaphoides (Jones) Rydb. 

 Bitterroot Milkvetch 



DESCRIPTION 



1. General description: Astragalus scaphoides is a member of 

 an extremely diverse genus in the Fabaceae (Pea or Bean 

 Family) . The plants are relatively large herbaceous 

 perennials with pinnately compound leaves borne on the 

 flowering stems. The inflorescence is a compact to somewhat 

 elongate raceme of many relatively large, bilaterally 

 symmetrical flowers. The perianth consists of a fused, five 

 lobed calyx and a cream to yellowish corolla which includes 

 a banner (the top segment), two wings (the side segments), 

 and a keel (the boat shaped bottom segment). There are 10 

 stamens, nine connected in a group and one free, and a 

 single ovary. The mature fruit is a distinctively stalked 

 legume which contains several seeds. An illustration of the 

 species is included in Appendix E. 



2. Technical species description (guoted from Hitchcock and 

 Cronguist 1961): Sparsely strigillose perennial with a 

 taproot and branched crown; stems several, stout, ascending 

 to erect, 2-6 dm tall; leaves 10-25 cm long; stipules 

 lanceolate, 1-4 mm long, not connate; leaflets 15-21, lance- 

 oblong to elliptic-oblong, 1.5-3.5 cm long, as much as 13 mm 

 broad, glabrous on the upper surface at least; peduncles 

 mostly 10-15 cm long; racemes closely 15- to 30-flowered but 

 elongating and open in fruit; pedicels 2-5 mm long; flowers 

 spreading to slightly reflexed, white to ochroleucous, about 

 2 cm long; calyx usually blackish-hairy, 8-10 mm long, the 

 narrowly lanceolate lower teeth about 2 mm long; banner 

 erect; wings 2-4 mm longer than the keel; pod erect, with a 

 stout upward-arching stipe about twice as long as the calyx, 

 the body 1.5-2 cm long, cartilaginous, glabrous, slightly 

 mottled, corrugate-wrinkled, oblong-ovoid, inflated and 

 slightly obcompressed, 4-6 mm broad, 6-10 mm thick, with 

 both sutures sulcate, the lower intruded to form a 3/4 

 complete partition. 



3. Diagnostic characters: The following combination of 

 characters separates this from other Montana species of 

 Astragalus (adapted from Dorn 1984): 



-Leaflets more than 5, not awl shaped 



-Hairs attached at their base 



-Stipules not united on side of stem opposite the petiole 



-Pods stipitate, glabrous, obcompressed with the lower 



suture nearly forming a partition within the fruit, 7- 

 20 mm wide, less than 3 times as long as wide 



-Calyx 8-12.5 mm long, banner more than 15 mm long 



