314 POLYGON ACE^. (BUCKWHEAT FAMILY.) 



rayed, usually some or all of the raijs once or twice divided. — From Colorado to 

 Nevada and Washington. 



-I- -i- Flowers not glabrous. 

 ++ Leafu : flowers not attenuate at base. 



4. E. salsuginosum, Hook. Low, glabrous, somewhat fleshy, di- or 

 trichotomously divided : leaves spatulate-oblanceolate, the bracts becoming 

 linear : involucres divided : flowers pubescent, yellow : sepals narrow, closely 

 appressed to the acutely triangular glabrous akene. — From S. W. Colorado 

 to Utah and W. Wyoming. 



•w- ++ Naked or nearly so : flowers attenuate at base. 

 = Bracts conspicuous : akenes glabrous or nearly so. 



5. E, Jamesii, Benth. Rather slender, herbaceous, with branching cau- 

 dex, a foot high or less, white-tomentose : leaves and bracts oblong-oblanceolate, 

 the latter shortly petiolate : involucres solitary, sessile, with 5 erect teeth, on a 

 naked peduncle : flowers whitish, silky. — Colorado, New Mexico, and Arizona. 



Var. flavescens, Watson. Stouter : floicers yellow or yellowish. — Dis- 

 tinguished from the next by the strictly solitary sessile involucres. 



6. E. flavum, Nutt. Tomeutose throughout, a span high or less: leaves 

 oblnnceolate : umbel of 3 to 9 rays, simple, on a naked peduncle : flowers yellow, 

 very silky. — Colorado to Washington and the Saskatchewan. 



7. E. CSespitOSUm, Nutt. Dwarf densely matted: leaves ovate- to oblong- 

 spatulate, tumenfose on both sides : involucres solitary on naked peduncles : flowers 

 yellow, pubescent. — From Wyoming to Nevada. 



8. E. sphaerocephalum, Douirl. Similar, but larger and 7nuch more 

 diffused: leaves linear-spatulate, often revolute : peduncles with a whorl of ob- 

 lanceolate bracts sometimes subtending a 2 to 4-rayed umbel, the lateral rays 

 also bracteate : floicers yellow, pubescent. — Nevada and California to Wash- 

 ington, and extending theuce eastward into ^Montana. 



= = Bracts small : akenes densely villous. 



9. E. acaule, Nutt. Very dicarf and densely matted and tomentose . 

 leaves crowded, oblong : peduncles naked, ^ inch high, bearing a head of \ to b 

 nearly sessile involucres: flowers pubescent. — S. W. Colorado to S. Idaho. 



10. E. laehnogynum, Torr. Cespitose and densely tomentose : leaves 

 oblong-lanceolate : the slender naked peduncle a foot high, sparingly dichotomous 

 above : ini'olucres solitary, sessile or long pedunculate : flowers densely tomen- 

 tose. — S. Colorado and New Mexico. 



§ 2. Involucres campanulate or short-turbinate, not nerved or angled, ivith 5 

 rounded erect teeth, pedunculate in diffuse repeatedly di- or trichotomous 

 panicles : bracts not foliaceous, all ternate : flowers not attenuate at base : 

 ovary glabrous. 



* Leaves tomentose. 



•»- Stems simple, leafy, naked above. 



11. E. annuum, Nutt. Tall and stout : leaves narrowly oblanceolate or 

 oblong, attenuate to a short petiole, mostly flat : inflorescence cymose : involu- 

 cres densely white-tomentose : flowers white : sepals very unequal, the outer 

 oblong-obovate. — Colorado to Texas and Mexico. 



