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 pediinculate 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 3. P. exile. 



Perennials. 



Corolla white or yellow 4. P. compadum. 



Corolla purple. 



Bracts glabrous; leaflets mucronulate 5. P. purpurcum. 



Bracts sericeous; leaflets obtuse 6. P. teiiuifolium. 



1. Petalostemum prostratum Woot. & Standi. Contr. U. S. Nat. Herb. 16: 138. 



1913. 



Type locality: Near Albuquerque, New Mexico. Type collected by Winnie Har- 

 ward (no. 17). 



Range: 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 locality: "Valley of the del Norte," New Mexico. Type collected by Emory 

 in 1847. 



Range: British America to Iowa, Colorado, and Arizona. 



New Mexico: Throughout the State. Open slopes, in the Upper Sonoran and 

 Transition zones. 



3. Petalostemum exile A. Gray, PL Wright. 2: 41. 1853. 

 Type locality: Hillsides, near Santa, Cruz, Sonora. 



Range: Southern New Mexico and Arizona and adjacent Mexico. 

 New Mexico: Mogollon Mountains. 



4. Petalostemum compactum (Spreng.) Swezey, Nebr. PI. Doane Coll. 6. 1891. 

 Dalea compacta Spreng. Syst. Veg. 3: 327. 1826. 



Petalostemum macrostachyum Torr. Ann. Lye. N. Y. 2: 176. 1828. 

 Type locality: "Ad fl. Rio Roxo in ditione Arkansa Amer. bor." 

 Range: Wyoming and Nebraska to Colorado and New Mexico. 

 New Mexico: Albuquerque; Pvito de los Frijoles; Dona Ana County. 



5. Petalostemum purpureum (Vent.) Rydf). Mem. N.Y. Bot. Gard. 1: 238. 1900. 

 Dalea purpurea Vent. PI. Jard. Cels. pi. 40. 1800. 



Petalostemum violaceum Michx. Fl. Bor. Amer. 2: 50. 1803. 

 Type locality: "Illinois." 



Range: British America to Missouri and New Mexico. 



New Mexico: NaraVisa. Pecos. Open hillsides and plains, in the Upper Sonoran 

 Zone. 



