Petalostemon. LEGUMINOSii:. 309 



28. PETALOSTEMON. Michx.Jl. 2. p. 48, t. 37 ; DC. prodr. 2. p. 213. 



Calyx often glandular, 5-toothed (rarely 5-clcft), sometimes a little curved ; 

 the teeth connivent, nearly equal. Petals 5, on filiform claws : four of them 

 nearly similar, their claws united to the stamen-tube (juite to the summit 

 (alternate with the stamens), and deciduous by an articulation; the fifth pe- 

 tal (vexillum) free, inserted at the bottorn of the calyx ; the limb cordate or 

 oblong, conduplicate. Stamens 5, monadelphous ; the tube cleft. Ovary 

 with 2 collateral ovules. Legume membranaceous, enclosed in the calyx, 

 indehisoent, 1-seeded. — Herbaceous, mostly perennial plants, dotted with 

 glands. Leaves unequally pinnate, exstipellate. Stipules minute, setace- 

 ous. Flowers in pedunculate dense terminal spikes or heads. 



1. P. camlidum (Michx.) : glabrous ; stem firm and erect ; spikes cylin- 

 drical, on long peduncles; bracts aristate, longer than the floAvers ; leaflets 

 3-4 pairs, lanceolate, sparingly dotted beneath; calyx nearly glabrous; petals* 

 ovate; vexillum broadly cordate. — Michx.! ft. 2. p. 49, t. 37, y! 1; DC. 

 prodr. 2. p. 243 ; Hook. ! fi. Bor.-Avi. 1. p. i37. Dalea Candida, JVilld. sp. 

 3. p. 1337. 



Dry prairies, Western and South Western States! north to the Sas- 

 katchawan River ! August. — Sparingly branched. Leaves an inch or more 

 in length, 2-3 lines wide. Spikes much elongated after flowering. Teeth 

 of the calyx shorter than the tube, ovate, somewhat pubescent on the margin, 

 with 2 glands near the base of each. Petals white. Ovary pubescent. 



2. P. gracile (Nutt.): glabrous; stem slender, decumbent or assurgent ; 

 spikes oblong-cylindrical, short ; bracts acute, as long as the calyx ; leaflets 

 3 pairs, linear-elliptical, slightly dotted beneath; petals ovate; vexillum broad- 

 ly cordate. — Nutt.! in jour. acad. Philnd. 7. p. 92. 



Lower part of Alabama, and in Florida, Nuttall ! Dr. Gales ! Texas 

 Drummond f — (I) Stem 1-2 feet long. Leaflets scarcely half an inch in 

 length, in the uppermost leaves often solitary. Spikes shorter than in the 

 preceding species, but the flowers nearly the same. Petals white. 



3. P. midlifiorum (Nutt.): glabrous; stem erect, branches fastigiate; 

 spikes roundish-oblong; calyx with the tube glabrous; the teeth short, pubes- 

 cent on the margin; petals ovate; leaflets 4-6 pairs, linear-oblong, with 

 black dots on both surfaces. — Nutt. ! in jour. acad. Philad. 7. /;. 92. 



Prairies of Arkansas, particularly on the Red River, Nuttall ! Dr. Leav- 

 enworth! Texas, Drummond! — About 2 feet high, much branched. Leaf- 

 lets 4-6 lines long. Spikes scarcely half an inch long. Petals white, round- 

 ed or slightly cordate at the base. — Our Texan specimens differ from the 

 Arkansas plant in the smaller leaflets, but not essentially in the flowers. 



4. P. macrostachyum (Torr.) : glabrous ; stem dotted ; leaflets 2-3 pairs, 

 lanceolate-oblong, obtuse, dotted beneath ; spike cylindrical, elongated ; bracts 

 lanceolate ; calyx silky-villous, the teeth lanceolate ; vexillum cordate. — Torr. ! 

 in ann. lye. New- York, 2. p. 176. P. ornatum, Dougl. ! in Hook. fl. Bor - 

 Am. 1. p. 138. 



About the Forks of the Platte, Dr. James ! Prairies on Lewis's River, 

 Oregon, Douglas ! (v. s. in herb. Hook.) — (T) ? Stem 1-2 feet high, branch- 

 ed. Leaflets about | of an inch long, the upper surface becoming of a deep 

 verdigris-green in drying. Spikes when old more than 6 inches long ; the 



* In describing the species of this genus, we call petals the 4 which alternate with 

 the stamens : the 5th petal being the vexillum. 



