546 EUPHORBIACEAE 



often broadened upwards. Bracts of the umbel-like inflorescence different from 

 the stem-leaves. Involucres sessile or peduncled; lobes often toothed. Glands 

 4, transversely oblong, reniform, or crescent-shaped, with the horn-like append- 

 ages pointing upwards. Capsule 3-lobed; lobes rounded, acute or keeled. Seeds 

 pitted. 



Leaves entire; glands of the involucres with processes, except in the first species. 

 Perennials with a woody base; processes short and blunt, or none. 



Stem-leaves linear; capsule rough; seeds smooth. 1. T. Cyparissias. 



Stem-leaves from oblong or oblanceolate to orbicular; capsule smooth or slightly 



wrinkled; seeds pitted. 

 Glands crenulate, obscurely horned; leaves small, ascending. 



2. T. luridus. 

 Glands distinctly horned; horns larger than the teeth (if any) between them; 



leaves large, spreading. . 



Bracts rhombic-ovate, cuspidate; stem rather slender. 3. T. philorus. 

 Bracts rhombic-reniform, mucronate; stem stout. 4. T. robustus. 



Annuals or perennials by means of sobols (suckers) ; processes of the glands long and 



horn-like. 



Seeds with small deep pits; leaves very thin. 5. T. commutatus. 



Seeds with broad shallow pits; leaves firm. 6. T. mancus. 



Leaves distinctly serrulate; plants annual or biennial; glands without processes. 

 Upper stem-leaves merely sessile; bracts manifestly longer than broad. 



7. T. arkansanus. 

 Upper stem-leaves with small auricles at the base; bracts mostly broader than long. 



8. T. missouriensis. 



1. T. Cyparissias (L.) Lam. Bright green, cespitose perennial; stems erect, 

 usually simple, 2-3 dm. high, very leafy; leaves 1.5-3 cm. long, 0.5-3 mm. broad; 

 bracts reniform or nearly orbicular; involucres 2 mm. long; glands crescent- 

 shaped; appendages none; capsule subglobose, 3 mm. thick; seeds oblong, 2 mm. 

 long. E. Cyparissias L. Waste places and around dwellings: Mass. Va. 

 Colo. Mont.; escaped and nat. from Eu. My-O. 



2. T. luridus (Engelm.) Woot. & Standl. Stems several from the woody 

 caudex, 1.5-3 dm. high, strict, very leafy; leaves oblanceolate or obovate, obtuse 

 or mucronate, 8-15 mm. long; bracts oblanceolate to rounded; involucres 2 mm. 

 long, hirsute within; glands transversely oblong; capsule 3 mm. thick; seeds 

 cylindric-ovoid, 2.4 mm. long. E, lurida Engelm. Arid regions: N.M. s Utah 

 Ariz. Son. Je-Jl. 



3. T. philorus Cockerell. Glabrous, cespitose perennial; stems branched, 

 erect, 1-3 dm. high; leaves ovate, lanceolate, or broadly oval, 0.5-2 cm. long; 

 involucres 2 mm. high; glands 0.5 mm. long, 1 mm. wide; capsule depressed-ovoid, 

 3 mm. high, 3.5 mm. wide; seeds ovoid-oblong, 2 mm. long, ash-colored. E. 

 montana Engelm., not Raf. Mountains: Colo. Utah Mex. Tex. Son. 

 Submont. Mr-Jl. 



4. T. robustus (Engelm.) Small. Robust, cespitose perennial; stems 1-3 

 dm. high; usually glabrous; stem-leaves oblong to broadly ovate, 1-2 cm. long, 

 often nearly as broad; involucres 2.5 mm. high, 1.5 mm. wide, hirsute inside; 

 glands often dentate between the short horns, 1-2 mm. wide; capsule depressed- 

 ovoid, 4-4.5 mm. wide; seeds ovoid, 2.3 mm. long, with shallow pits. E. mon- 

 tana robusta Engelm. Mountains: S.D. Mont. Ariz. N.M. Neb. Plain 

 Submont. My-Jl. 



6. T. commutatus (Engelm.) Kl. & Garke. Annual or perennial by means 

 of shoots from the decumbent stems, 1.5-3 dm. high, branched at the base; 

 stem-leaves obovate, obtuse or retuse, 0.5-3 cm. long; those of the sterile branches 

 oblanceolate; bracts triangular-reniform; glands 1-1.5 mm. wide, yellow or 

 brown when old; horns white, twice as long; capsule 3 mm. thick; seeds sub- 

 globose. E. commutata Engelm. River valleys and sandy soil: Pa. N.C. 

 Tex. Wis. Mont. Plain. My-Jl. 



6. T. mancus (A. Nels.) Heller. Annual; stems 1-3 dm. high, branched at 

 the base, erect, or decumbent below; leaves spatulate or obovate, obtuse, 1-2 

 cm. long; bracts ovate-reniform, connate especially on the outside, 1-2 cm. 

 wide and more than half as long; glands 2 mm. wide, with divergent horns; cap- 

 sule 4 mm. long, somewhat broader; seeds oblong-ovoid. E. manca A. Nels. 

 Valleys: Colo. Ariz. 



