278 MISC. PUBLICATION 42 3, U. S. DEPT. OF AGRICULTURE 



15. SALSOLA 



An annual much-branched herb, becoming hard and prickly; leaves 

 awl-shaped, spine-tipped; flowers perfect, each subtended by 2 

 bractlets, sessile, axillary; perianth 5-parted, in fruit with horizontal 

 scarious dorsal wings; stamens commonly 5; styles 2; seed horizontal. 



1. Salsola pestifer A. Nels. in Court., New Man. Rocky Mount. 169. 

 1909. 



Extensively naturalized in the western United States; introduced 

 from Eurasia. It is perhaps better regarded as a variety of S. kali L. 

 (var. tenuifolia Tausch). 



Russian-thistle. Abundant along roads in some of the irrigated 

 districts of southern Arizona and on overgrazed ranges in the northern 

 part of the State. In early spring the young plants are readily eaten 

 by livestock, and the dead plants are eaten in winter after softening by 

 rains. In case of need good ensilage can be made from the mature 

 plants, which otherwise are unpalatable. Hay sometimes is made of 

 the young plants. The plant is a typical "tumbleweed," breaking off 

 at the surface of the ground when mature and piling up along fences. 

 One of the Hopi Indian names signifies "white man's plant." 



35. AMARANTHACEAE. Amaranth family 



Stems herbaceous or slightly woody below; leaves simple, entire, 

 without stipules; flowers small, unisexual or some of them perfect, 

 commonly in dense heads or spikes; perianth scarious, hyaline, or 

 papery; ovary 1-celled; fruit a utricle, circumscissile or bursting 

 irregularly. 



Key to the genera 



1. Leaves alternate; anthers 4-celled, appearing 2-celled after dehiscence; plants 

 annual, without lanate pubescence (2). 

 2. Pistillate flowers with a perianth, not concealed by the bracts, these narrow, 

 not cordate 1. Amaranthus. 



2. Pistillate flowers without a perianth, more or less concealed by broad, 



cordate, spine-tipped, scarious-margined bracts 2. Acanthochiton. 



1. Leaves opposite; anthers 2-celled, often appearing 1-celled after dehiscence (3). 



3. Stamens adnate to the perianth, perigynous 3. Brayulinea. 



3. Stamens free from the perianth, hypogynous (4). 



4. Perianth segments united into a tube, this in fruit hardened and 

 longitudinally crested, winged, or bearing longitudinal rows of 



spines 5. Froelichia. 



4. Perianth segments separate or united only near the base, not forming an 

 appendaged tube in fruit (5). 

 5. Flowers in few-flowered, rather loose axillary glomerules, these sub- 

 tended by leaves with the bases becoming more or less hardened 

 and united, forming a turbinate involucre; plants with lanate 



pubescence 4. Tidestromia. 



5. Flowers in dense heads or spikes, these naked or, if subtended by leaves, 

 their bases not becoming hardened and united; pubescence not 

 lanate; bracts of the inflorescence thin, scarious, white, yellowish, 

 or pink (6). 



6. Stigma capitate 6. Achyranthes. 



6. Stigma with 2 or 3 subulate or filiform lobes (7) . 



7. Flowers perfect, in globose or ovoid heads, these terminal or 

 both terminal and axillary, solitary or in dense subcapitate 



clusters 7. Gomphrena. 



7. Flowers dioecious, in a loose panicle of numerous slender 

 spikes - 8. Iresine. 



