MILKWORT FAMILY 541 



1. P. verticillata L. Stem 0.5-3 dm. high, angled, with numerous spread- 

 ing branches; leaves in 4's or 5's, 1-3 cm. long; racemes spike-like, narrowly 

 conic; flowers greenish or greenish white; wings ovate, about 1 mm. long; keel 

 crested with several thick processes; capsule about 2 mm. long. Dry soil: 

 Que. — Fla. — Mex. — Wyo. — Sask. Plain — Submont. Je-S. 



2. P. alba Nutt Stems several from the base, erect or ascending, 1-5 dm. 

 high, angled, simple; leaves 1-2.5 cm. long; racemes spike-like, 4-6 mm. thick; 

 wings oval or obovate, 2-3 mm. long; corolla white; keel with a fimbriate crest; 

 capsule ovoid, 2-3 mm. long. Dry plains: Minn. — Kans. — Tex. — Ariz. — Colo. 

 — Mont.; Mex. Plain. Ap>-0. 



3. P. Senega L. Stems several from a thick root, erect, 1-5 dm. high, 

 simple; leaves numerous, lanceolate to lance-elliptic or (in var. latifolia) ovate- 

 lanceolate or ovate, scabrous on the margin; racemes spike-like, 2-6 cm. long; 

 wings orbicular-ovate, 2-3 mm. long; corolla greenish white, 3-4 mm. long; keel 

 crested with thick processes; capsule flat, broader than long. Dry soil: N.B. — 

 N.C.— Ark.— (Black Hills) S.D.— Alta. Submont. My-Jl. 



4. P. subspinosa S. Wats. Spinescent vmdershrub, intricately branched, 

 puberulent; leaves lance-oblong to elliptic or spatulate, 1-2 cm. long, firm; 

 inflorescence a few-flowered raceme; wings elhptic-oblong, acutish, as well as 

 tips of the lateral petals rose-colored; keel yellow, with a blunt beak; capsule 

 obovate, refuse, veiny, glabrous. Foot-hills: Colo. — ^Ariz. — -Nev. Son. — Sub- 

 mont. My-Jl. 



5. P. acanthoclada A. Gray. Spinescent shrub, with white or yeUowish 

 bark, intricately branched; leaves 6-12 mm. long; oblanceolate or spatulate; 

 racemes few-flowered, with a stout peduncle produced into a spine; flowers yellow- 

 ish white, or the petals tipped ■with purphsh; wings obovate; keel "nnth a very short 

 blunt, often obsolete, beak; fruit oblong-ovate, 5 mm. long, deeply notched. 

 Arid regions: Colo. — ^Ariz. — Nev, Son. Je. 



Family 74. EUPHORBIACEAE. Spurge Family. 



Monoecious or dioecious herbs (all ours), or shrubs or trees, often with 

 milky sap, and alternate, opposite, or verticillata simple leaves. Flowers 

 with or without petals, sometimes much reduced and subtended by a calyx- 

 like involucre. Stamens few or many; filaments united or distinct. Ovary 

 usually 3-celled. Stjdes as many as the cells of the ovary, simple, divided, 

 or many-cleft. Capsule separating at maturity into three 2-vaIved carpels. 



Flowers not in involucres; calyx of several sepals. 



Corolla present in either the staminate or pistillate flowers, or in both. 



Stamens 5 or 6; filaments distinct. 1. Crotox. 



Stamens 10; filaments monadelphous. 2. Ditaxis. 



Corolla wanting. 3. Tragl\. 



Flowers in involucres; caly.x represented by a minute scale on the fllament-Uke pedicels. 

 Glands of the involucres with petal-Uke appendages, these however sometimes much 

 reduced. 

 Leaves all opposite. 



Leaf-blades obhque at the base, inequilateral; glands 4. 4. CHAiL\ESTCE. 

 Leaf-blades equilateral, not obhque at the base; glands 5. 



5. ZTGOPHTLLIDrUM. 



Leaves alternate or scattered, at least below the inflorescence; annuals or bien- 



enials; bracts petal-like. "6. Lepadexlv. 



Glands of the involucres without petal-Uke appendages, entirely naked, sometimes 



with crescent-shaped horns. 

 Stem topped by an umbel; stipules none; involucres in open cymes, each with 4 



glands and entire or toothed lobes. 7. Tithy\l\lus. 



Stem not topped by an umbel; stipules gland-Uke; involucres ia conglomerate 



cymes, each with a single gland, or rarely 4 glands and fimbriate lobes. 



8. POIXSETTIA. 



1. CROTON L. CrotoxX. 



Herbs (ours) or shrubs, monoecious or rarely dioecious, heavy-scented, stel- 

 late-pubescent or scaly, sometimes more or less glandular. Leaves mostly alter- 

 nate, entire, toothed or lobed. Flowers in axillary or terminal clusters. Stam- 



