FLOWERING PLANTS AND FERNS OF ARIZONA 283 



The whitish mats of this plant are conspicuous soon after summer 

 rains on the deserts in southern Arizona, and are well adapted for 

 checking the blowing of sandy soils. 



2. Tidestromia oblongifolia (S. Wats.) Standi., Wash. Acad. Sci. 

 Jour. 6: 70. 1916. 

 Cladothrix oblongifolia S. Wats., Amer. Acad. Arts and Sci. 

 Proc. 17: 376. 1882. 

 Mohave and Yuma Counties, 5,000 feet or lower, in sandy soil, June 

 to October. Arizona, Nevada, and southeastern California. 

 Plant often shrubby, up to about 0.6 m. high. 



5. FROELICHIA. Snakecotton 



Plants herbaceous, annual or perennial, lanate-tomentose; stems 

 erect, sparingly branched; flowers perfect, subtended by glabrous, 

 dark-colored bracts, in somewhat elongate glomerules, these forming 

 terminal panicles or interrupted spikes; stamens 5, the filaments 

 united; utricle indehiscent. 



The plants are relished by livestock. 



Key to the species 



1. Plant annual; stems slender, simple or branched at base, leafy only near the 

 base, commonly not more than 30 cm. long; leaf blades thin, lanceolate, 

 1 cm. wide or narrower 1. F. gracilis. 



1. Plant perennial, with a thick woody root; stems stout, often sparingly branched 

 above the base, commonly leafy well above the base, often much more than 

 30 cm. long; leaf blades thick, commonly oblanceolate and 1 to 2 cm. wide. 



2. F. ARIZOXICA. 



1. Froelichia gracilis Moq. in DC, Prodr. 13 2 : 420. 1849. 

 Navajo and Yavapai Counties south to Cochise County, 4,500 to 



5,500 feet, summer. Iowa to Colorado, south to Chihuahua and 

 Arizona. 



2. Froelichia arizonica Thornber ex Standi., North Amer. Fl. 21: 128. 



1917. 

 Cochise, Santa Cruz, and Pima Counties, 3,500 to 5,500 feet, on dry 

 grassy plains and slopes, late summer. Western Texas, southern 

 Arizona, and northern Mexico. 



Closely related to and perhaps not specifically distinct from F. 

 floridana (Nutt.) Moq. 



6. ACHYRANTHES 



Plant herbaceous, perennial, with a thick, woody, vertical root; 

 stems prostrate or procumbent, forming mats; leaves opposite, with 

 oval or obovate blades, those of the pair very unequal; flowers perfect, 

 in short axillary spikes, with conspicuous white bracts; sepals 5, 

 pubescent with stiff-jointed hairs, these minutely barbed at apex. 



1. Achyranthes repens L., Sp. PI. 205. 1753. 



Alternanthera repens (L.) Kuntze, Rev. Gen. PL 2: 540. 1891. 



Tombstone, Cochise County (Peebles et al. 3374), Huachuca 

 Mountains, Cochise County (Jones in 1903), Patagonia, Santa Cruz 

 County (Peebles et al. 4652), 4,000 to 5,500 feet, summer. South 

 Carolina to Arizona, south to tropical America. 



A roadside weed, resembling Brayvlinea dt nsa but with larger leaves 

 nd flower spikes. 



