24-4 EuniOKBiACE.E (]>roAvn). [UiqiJwrhia, 



Fl<jwering-eyes 2-4 lin, above the spine- 

 shiekls and quite separate fi'oni them ; 

 .•mgles of young branches not more than 

 1^ liii. thick at the edges between the 

 spine -shiekl;i ... ... ... • . O^lCi) similis. 



Flowering-eyes nearly or quite touching the 

 ppine-shields : 

 Branches erect or ascending, forming an 

 obconic crown ; angles 2J-3 lin. thick 

 at the edges ; spine-shields of a thin 

 disintegrating substance and often 

 spineless, suborbicular or transverse, 

 rust-coloured (17''>) ingens. 



Branches spreading and upcurved, forming 

 a rounded crown ; angles 1^-2 Hn. 

 thick at the edges ; spine-shields 

 horny, lonp:er than broad, free or 

 united into a horny margin (177) triangularis. 



Flowering branches ^-2 in. in diam., 3-5-angIed 

 or flat and 2-angled, usually less than IJ 

 lin. thick at the edges between the spine- 

 shields : 

 Flowering branches 1-2 in. in diam. ; spine- 

 shields sometimes united into a horny 

 margin ,. ... (178) Evansii. 



Flowering branches J-1 in. in diam. ; spine- 

 shields free, never united into a horny 

 margin ; ilowering-eyes touching the 

 spme-shields : 



Flowering brandies often 3- (sometimes 2-) 



angledj conspicuously toothed ... (179) grandidens. 



Flowering branches usually 4- .5- (some- 

 times 3-) angledj often rather slightly 

 toothed (180) tetragona. 



ttI5nshes or shrubs 2-8 ft. high, with the spine-shields 



united into a continuous horny margin or 

 sometimes free : 

 Stems simple or occasionally sparingly branched, 

 4-8 ft. high, 5-7-angled, constricted into 

 ellipsoidal segments (172) virosa. 



Stems more or less branched, 2-8 ft. high : 



Branches 3-4-angled ; flowering-eyes seated 



nearly midway betweeii two pairs of spines (lf)9) frankiana. 



Branches 4-7-angled ; flowering-eyes seated at 

 about one-third of the <listance up between 

 two pairs of spines : 

 Stems more or less glaucous or bluish-green ; 

 spines 3-G lin. long, g-J lin. thick ; in- 

 volucre unknown ... (170) coerulescena. 



Stems green, not glaucous ; spines 1-3 lin. 

 long, J-J Hn. thick, sometimes absent ; 

 involucre narrowly obconic, yellow ►., (171) LedieniL 



ttfDwarf plants, less than 1 ft. high and usually only 



attaining 3-6 in. above the ground, often with 

 a thick tuberous rootstock : 

 Spines subconnate at the ba.se, then diverging ; 

 tul^rcles on the angles crowded, spirally 

 arranged ,., (IGl) mammiUosa 



