WOOTON AND STANDLEY—FLORA OF NEW MEXICO. 355 
16. PETALOSTEMUM Michx. PRAIRIE CLOVER. 
Herbaceous glandular-punctate annuals or perennials with odd-pinnate leaves, the 
flowers in dense pedunculate terminal spikes or heads; calyx with 5 connivent teeth; 
petals with filiform claws, 4 of them nearly alike and adnate by their claws to the 
stamen tube, the banner free; stamens 5, monadelphous; pods membranous in the 
persistent calyx, indehiscent, 1-seeded. 
KEY TO THE SPECIES. 
Stems prostrate; flowers purplish.......--.----------------+---- 1. P. prostratum. 
Stems erect; flowers variously colored. 
Calyx glabrous; corolla white.............------+--+++--+-+- 2. P. oligophyllum. 
Calyx pubescent; corolla variously colored. 
Annual... 2.22... -. 2 eee eee ee eee eee eee eee eee ee eee 3. P. evile. 
Perennials. 
Corolla white or yellow...........- weeeee wee eeeee 4. P. compactum. 
Corolla purple. 
Bracts glabrous; leaflets mucronulate........- 5. P. purpureum. 
Bracts sericeous; leaflets obtuse. .-.-.--.------ 6. P. tenutfolium. 
1. Petalostemum prostratum Woot. & Standl. Contr. U. 8. Nat. Herb. 16: 138. 
1913. 
Typr Locauiry: Near Albuquerque, New Mexico. Type collected by Winnie Har- 
ward (no. 17). 
Rance: Rio Grande Valley of central New Mexico. 
New Mexico: Near Albuquerque; near Belen. Lower Sonoran Zone. 
A remarkable species, distinguished from all our others by its prostrate habit. In 
general appearance it resembles some species of Parosela, 
2. Petalostemum oligophyllum (Torr.) Rydb. Mem. N.Y. Bot. Gard. 1: 237. 1900. 
Petalostemum gracile oligophyllum Torr. in Emory, Mil. Reconn. 139. 1848. 
TypE Loca.iry: ‘‘ Valley of the del Norte,’’ New Mexico. Type collected by Emory 
in 1847. 
Rance: British America to Iowa, Colorado, and Arizona. 
New Mexico: Throughout the State. Open slopes, in the Upper Sonoran and 
Transition zones. 
8. Petalostemum exile A. Gray, Pl. Wright. 2: 41. 1853. 
Type Loca.iry: Hillsides, near Santa Cruz, Sonora. 
Rance: Southern New Mexico and Arizona and adjacent Mexico. 
New Mexico: Mogollon Mountains. 
4. Petalostemum compactum (Spreng.) Swezey, Nebr. Pl. Doane Coll. 6. 1891. 
+ Dalea compacta Spreng. Syst. Veg. 3: 327. 1826. 
Petalostemum macrostachyum Torr. Ann. Lyc. N. Y. 2: 176. 1828. 
Tyre Locauiry: ‘‘Ad fl. Rio Roxo in ditione Arkansa Amer. bor.”’ 
Rance: Wyoming and Nebraska to Colorado and New Mexico. 
New Mexico: Albuquerque; Rito de los Frijoles; Dona Ana County. 
5. Petalostemum purpureum (Vent.) Rydb. Mem. N. Y. Bot. Gard. 1: 238. 1900. 
Dalea purpurea Vent. Pl. Jard. Cels. pl. 40. 1800. 
Petalostemum violaceum Michx. Fl. Bor. Amer. 2: 50. 1803. 
Type Locauity: ‘‘Illinois.’’ 
Range: British America to Missouri and New Mexico. 
New Mexico: Nara Visa. Pecos. Open hillsides and plains, in the Upper Sonoran 
Zone. 
