228 POLYGONACEAE 



broad, pilose on both sides; secondary leaves with orbicular blades; involucres 

 turbinate; perianth whitish or yellowish, 1-1.5 mm. long; lobes oblong, subequal. 

 Clay hills: Wyo. — Colo. — -Ariz. — -Utah. Son. — ■Siibmont. Je-S. 



118. E. angulosum Benth. Stem 1-4 dm. high, di- or tri-chotomously 

 branched; basal leaves petioled, sjjatulate, 2-5 cm. long; primary stem-leaves 

 lanceolate, stipule-like; secondarv ones fascicled, oblong, linear, or oblanceolate; 

 peduncles 1-3 cm. long, divaricate; involucres shortly turbinate, 2 mm. long, 

 minutely glandular; lobes rounded; perianth rose-colored or white, deeply 5- 

 cleft, about 2 mm. long, the outer lobes ovate, the inner ones oblong or lanceo- 

 late, obtuse. Arid regions: Ariz. — Ida. — Calif. Son. Ap-0. 



119. E. puberulum S. Wats. Scape 5-15 cm. high, canescent, dichoto- 

 mously branched; leaf -blades obovate to broadly oval or suborbicular, 5-15 

 mm. broad, grayish short-pubescent; bracts more or less foliaceous, narrowly 

 oblong, 3-5 mm. long; involucres sessile in the forks, very small, 4-lobed; peri- 

 anth glabrous, rose-colored, 1.5-2 mm. long; lobes oblong. Sandy soil: Utah. 

 Son. — Suhmont. Je. 



120. E. spergulinum A. Gray. Stem 1-3 dm. high, slender, dichotomously 

 branched, glandular-pruinose and more or less hirsute below; leaves and bracts 

 verticillate, linear, green on both sides, hirsute; involucres on slender reflexed 

 peduncles, glabrous, 4-cleft, 1-1.5 mm. long; perianth white, pilose at the base, 

 2 mm. long. Sunny slopes: Calif. — Nev. — -Ida. — 'Ore. Son. Jl-Au. 



121. E. pharnaceoides Torr. Stem slender, 1-3 dm. high, villous; leaves 

 and bracts verticillate, linear, revolute-margined, villous above, tomentose 

 beneath; involucres on slender peduncles, turbinate, 3 mm. long, villous; lobes 

 lanceolate, as long as the tube; perianth rose-colored, 2.5-3 mm. long; outer 

 segments oval, saccate below, glabrous; the inner ones oblong. Rocky hills: 

 N.M.— Utah— Ariz. Son. Jl-S. 



122. E. salsuginosum Hook. Stem branched from the base, 1-2 dm. high, 

 trichotomous, leafy; basal leaves fleshy, spatulate, 2-4 cm. long; stem-leaves 

 linear; involucres partly sessile in the forks, partly long-peduncled, of nearly 

 distinct lanceolate bracts; perianth yellowish, hirtellous without; lobes oblong- 

 lanceolate; filaments and pistils glabrous. Clayey hills: Wyo. — N.M. — Utah. 

 Son. — Submont. My-Jl. 



2. OXYTHECA Nutt. 



Diffuse dioecious or monoecious annuals, more or less glandular. Leaves 

 rosulate at the base. Inflorescence trichotomously cymose. Bracts ternate, 

 foliaceous and more or less connate, often awned. Involucres few-flowered, 

 campanulate or turbinate, herbaceous, 3-5-cleft; lobes erect or spreading, end- 

 ing in straight awns. Perianth 6-parted. Stamens 9, inserted near the base of 

 the perianth. Achenes lenticular. 



Stem-leaves and bracts lanceolate, connate only at the base; involucres pedlcelled. 



1. O. foliosa. 

 Stem-leaves and bracts connate, forming a nearly circular disk; involucres sessile. 



2. O. perfoliata. 



1. O. foliosa Nutt. Stem 1-3 dm. high, with ascending branches; basal 

 leaves lincar-oblanceolate, 3-6 cm. long, pilose; invohicres 1-2 mm. long; lobes 

 somewhat unequal, the awns very unequal and varying in length; perianth light 

 rose-colored; lobes 6, obovate, 0.5-0.75 mm. long. Dry regions: Wash. — -Wyo. — 

 Nev. Son. Je-Jl. 



2. O. perfoliata T. & G. Annual; stem dichotomously branched, sparingly 

 glandular, 1-2 dm. high; basal leaves spatulate, 1-4 cm. long, glabrous; stem- 

 leaves and bracts 3 at each joint, forming a disk 1-2 cm. broad, with 3 bristle 

 points; involucres in the forks; lobes subulate-lanceolate, ending in an awn of their 

 own length; flowers 4-6, pedicellate; perianth i)ubescent. Arid regions: Nev. — 

 Ariz. — s Utah. L. Son. Je. 



3. CENTROSTEGIA A. Gray. 



Branched annuals. Leaves basal, spatulate. Inflorescence cymose-pan- 

 iculate. Bracts usually 3-fid; lobes spinulose-cuspidate. Involucres sessile, 



