EUPHORBIACEAE 691 



b. Flowers either staminate or pistillate or both in cymes or corymbs, or 

 if racemose pistillate terminal, if clustered on spurs corolla present. 

 Leaf-blades peltate. 18. RiciNus. 



Leaf-blades not peltate. 



Flowers clustered on leafy spurs. 19. Mozinna. 



Flowers in more or less open cymes or panicles. 

 Flowers in forking cyme-like panicles. 



Stamens 10 or more : petals wanting. 20. Cnidoscolus. 



Stamens 10 or fewer : petals present. 21. Jatropha. 



Flowers in simple or branched racemes. 22. Manihot. 



B. Flowers in involucres : calyx represented by a minute scale at the base of a 

 filameut-like pedicel.' 

 Glands of the involucres with petal-like appendiiges, these sometimes much 

 reduced. 

 Leaves all opposite. 



Leaf-blades inequilateral, oblique at the base. 23. Chamaesyce. 



Leaf-blades equilateral, not oblique at the base. 24. Zygophyllidil'm. 



Leaves alternate or scattered at least below the inflorescence. 



Stems terminating in a spicate or racemose inflorescence. 25. Tricherostigma. 



Stems topped by simple or compound umbels. 



Annual or biennial : stipules narrow : bracts petal-like. 26. Picrophyllum. 



Perennial : stipules none]: bracts not petal-like. 27. Tithymalopsis. 



Glands of the involucres without petal-like appendages, entirely naked, some- 

 times with crescent-like horns. 

 Stem topped by an umbel : stipules none : involucres in open cymes, each 



with 4 glands and entire or toothed lobes. 28. Tithymalus. 



Stem not topped by an umbel : stipules gland-like: involucres in cluster-like 



cymes, each with a single gland or rarely 4 glands and fimbriate lobes. 29. Poinsettia. 



1. ANDRACHNE L. 



Herbs or shrubby plants, with branching, sometimes diffuse stems. Leaves alternate : 

 blades often entire, petioled. Flowers monoecious, axillary : staminate commonly clus- 

 tered ; calyx of 5 or 6 sepals ; petals 5 or 6 ; disk glandular or lobed ; stamens 5 or 6, 

 their filaments distinct. Pistillate flowers solitary : calyx of 5 or 6 sepals : petals minute 

 or wanting : ovary 3-celled : styles distinct, 2-cleft or 2-parted. Ovules 2 in each cavity. 

 Cap.sule becoming dry, separating into three 2-valved carpels. Seeds somewhat curved, 

 with a rugose testa. 



Foliage glabrous to the twigs : leaf-blades longer than broad, rounded or cuneate at the base. 



1. A. pliyllanthoides. 

 Foliage somewhat hirsute : leaf-blades as broad as long, subcordate at the base. 2. A. Revcrchonii. 



1. Andrachne phyllanthoides (Nutt. ) Muell. Arg. A straggling much branched 

 shrub 3-9 dm. tall, with lustrous glabrous branches and minutely pubescent twigs. Leaves 

 numerous, bright green : blades obovate or oval, 7-20 mm. long, obtuse or refuse at the 

 apex, often mucronulate, paler beneath than above : pedicels filiform, 5-20 mm. long, 

 glabrous: sepals oblong-obovate, L 5-3 mm. long, spreading: petals various, those of the 

 staminate flowers greenish yellow, narrowly obovate or oblong-obovate, 3-5-toothed : 

 those of pistillate flowers much smaller, broadly obovate, entire : capsules subglobose, 

 rather fleshy until mature. 



On rocky barrens, Missouri to Arkansas and Texas. Summer. 



2. Andrachne Reverchonii Coulter. A branching shrub 3-6 dm. tall, with sparingly 

 hirsute foliage, and reddish more or less curved stems. Leaves alternate, approximate : 

 blades suborbicular or cuneate-orbicular, 8-16 mm. long, glabrate above, pale-green, trun- 

 cate or retuse at the apex, entire, subcordate at the base : sepals oblong or nearly so, 

 ciliate : petals cuneate, shorter than the sepals, those of staminate flowers more distinctly 

 denticulate than those of pistillate flowers : capsules depressed, less than 1 cm. broad. 



On rocky prairies, Texas. Spring. 



2. PHYLLANTHUS L. 



Annual or perennial herbs, or often shrubs or trees in the tropics. Leaves alternate, 



often numerous, sometimes so arranged as to appear like the leaflets of a compound leaf: 



blades entire, commonly sessile. Flowers monoecious, apetalous, sessile or pedicelled, a 



staminate and a pistillate one together in an axil, sometimes on the edges of leaf-like 



branches. Sepals mostly 5-6, imbricated. Stamens usually 3 : filaments more or less 



united, rarely separate. Ovary 3-celled : styles 3, each 2-cleft. Ovules 2 in each cavity. 



Capsule globose or depressed, each carpel 2-seeded. 



A. Annual, or perhaps sometimes perennial, species : stems solitary and mostly simple at the base. 

 Capsules 3 mm. broad. 1. P. Avicularia. 



Capsules 2 mm. broad. 



a. Branches erect or ascending : sepals 6. 2. P. Carolinensis. 



^ The following genera are commonly included in the composite genus Euphorbia, but the 

 name Euphorbia is to be associated with certain of the Cactus-like relatives of the Old World. 



