20 POLYGONACEAE 



I. EUERIOGONUM 



Perennials with a simple or usually a branched and more or less cespitose woody 

 caudex. Leaves borne on the ends of the caudex branches, often tufted. Flowering stems 

 scapiform, bractless or with a whorl of bracts near the middle or at the base of the umbel. 

 Umbels simple or sometimes compound, bearing a single involucre at the end of each ray, 

 sometimes congested into heads by shortening of the rays; involucres turbinate, neither 

 ribbed nor angled, 4-8-toothed or -lobed. Calyx narrowed to a stipe-like base, accrescent, 

 the lobes oblong-obovate. 



Calyx pubescent on the outer surface, at least toward the base, sometimes glabrous or nearly so in tenue. 

 Involucre more or less deeply lobed, the lobes spreading and usually reflexed in age. 

 Bracts none; involucres solitary at the end of the naked scapiform flowering stem. 



1. E. caespitosum. 

 Bracts present, in plants with a single ray and a solitary involucre appearing as if near the middle of 

 the stem, and in those with umbels subtending the umbel. 



Caudex branches decumbent forming mats; leaves densely white-tomentose on both surfaces; bracts 

 appearing near the middle of the stem; involucre solitary, not umbellate. 



Leaves spatulate to ovate, not revolute. 2. E. Douglasii. 



Leaves linear, revolute; calyx sometimes nearly or quite glabrous. 3. E. tenue. 



Caudex branches mostly erect, 10—20 cm. high; leaves white-tomentose beneath, greener and gla- 

 brate above; involucre usually umbellate. 



Calyx villous with spreading hairs, the lobes 5-6 mm. long, the tube 2 mm. long. 



4. E. sphaerocephalum. 

 Calyx silky-tomentose with short appressed hairs, the lobes 3—4 mm. long and the tube scarcely 

 1 mm. long. 5. E. tripodutn. 



Involucre toothed at the apex, the teeth short and erect or nearly so. 

 Bracts and involucre herbaceous. 



Bracts appearing in a whorl near the middle of the flowering stem; involucre solitary; leaves linear, 



revolute, tomentose. 6. E. thymoides. 



Bracts subtending the umbel; rays short, 1 to several. 



Leaves oblanceolate; bracts several; calyx yellow; filaments hairy. 7. E. Piperi. 

 Leaves ovate to suborbicular; bracts 2; calyx rose-colored; filaments glabrous. 



8. E. pyrolaefolium. 



Bracts and the involucres membranous and rose-colored; plants bright green and nearly glabrous. 



9. E. latens. 

 Calyx glabrous on the outer surface. 



Involucres merely toothed at the apex, the teeth short and erect or nearly so. 



Bracts forming a whorl near the middle of the flowering stem; involucre solitary without subtending 

 bracts. 

 Involucre narrowly turbinate, silky-tomentose, the teeth short, erect. 10. E. Kelloggii. 



Involucre campanulate, arachnoid-tomentose, the teeth reflexed, about as long as the tube. 



11. E. siskiyouense. 

 Bracts subtending the open or subcapitate umbel. 



Styles scarcely 0.5 mm. long, erect or slightly spreading, turgid, glabrous. 



Umbel mostly congested; leaves densely white-tomentose on both sides, mostly acute at base. 



12. E. incanum. 

 Umbel usually open; leaves becoming glabrous above, mostly rounded at base. 



13. E. marifolium. 



Styles 2.5-3.5 mm. long; filaments 3-4 mm. long, densely long-woolly below, the wool filling the 

 throat of the calyx. 



Leaves broadly ovate, rounded or subcordate at base; flowers ochroleucous. 



14. E. ursinum. 



Leaves obovate to spatulate, attenuate at base; flowers sulphur yellow. 



15. E. ternatum. 



Involucres lobed, the lobes oblong or ovate-oblong, spreading or usually reflexed in age. 



Stipes with a whorl of foliaceous bracts near the middle as well as at the base of the umbel; flowers 



ochroleucous. 16. E. heracleoides. 



Stipes bracteate only at the base of the umbel (rarely with a solitary bract near the middle, or in some 

 forms the umbel reduced to a single ray and a single involucre, then the whorl of bracts appear- 

 ing as if on the stipe). 

 Flowers sulphur yellow or red. 17. E. umbellatum. 



Flowers ochroleucous. 



Stipes erect, often 3-5 dm. tall; leaves often 10-20 cm. long, mostly cordate at base. 



18. E. compositum. 



Stipes decumbent, 1-2 dm. long; leaves 5-10 cm. long, never cordate at base. 



19. E. Lobbii. 



II. Ganysma 



Annuals, or trichopes and inflatum sometimes persisting through the winter. Stems 

 solitary or sometimes several from the tuft of basal leaves, more or less repeatedly di- 

 chotomously or trichotomously branched above, bearing a pair of small triangular more 

 or less connate bracts at the nodes, and in some species also cauline leaves. Involucres 

 solitary at the nodes, borne on slender pedicel-like peduncles, small, mostly 1-2 mm. long, 

 turbinate or campanulate, 4-5-toothed or -lobed, not angled ; filaments and pistil glabrous ; 

 achenes more or less 3-angled. 



Involucres 4-lobed or 4-toothed. 



Stem leaves all foliaceous except those of the uppermost nodes. 



Plants more or less woolly-tomentose; involucre 1.5-2 mm. long; stem leaves opposite, sessile. 

 Flowers not concealed by cotton-like tomentum. 



