152 



EUPHORBIACEAE 



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

 horn-4ike. 

 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. 



8. POINSETTIA Graham. Spurge. 



Gland or glands of the involucre stalked; bracts and upper leaves slightly if at all dis- 

 colored. 

 Seeds not prominently tubercled; glands of the involucre 3—4; leaf-blades linear or 

 linear-lanceolate. 1. P. cuphusperma. 



Seeds prominently tubercled; gland of the involucre soUtary; leaf-blades ovate to 

 lanceolate (linear-lanceolate only in one variety). 2. P. dentata. 



Gland of the involucre sessile or nearly so; bracts and upper leaves discolored at the base; 

 leaf-blades very variable, the upper usually flddle-shaped. 3. P. heterophylla. 



Family 75. CALLITRICHACEAE. Watek Starwort Family 

 1. CALLITRICHE; L. Water Starwort. 

 Characters of the family. 



3-nerved 



Upper floating leaves obovate or spatulate, 



bracts. 

 All leaves linear, 1-nerved; flowers bractless. 



flowers subtended by a pair of 



1. C. palustris. 



2. C. autumnalis. 



Family 76. CELASTRACEAE. Staff-tree Family. 



aril crimson. 



1. Ceiastrus. 



2. euontmus. 



3. Pachystima. 



4. mohtonia. 



5. porsellesia 



Stamens as many as the petals and sepals. 



Fruit a locuhcidal capsule; seeds with an aril. 



Shrubby vines, with alternate leaves; ovary free from the disk; 



Shrubs, with opposite leaves: ovary inmaersed in the disk. 

 Capsule 3-5-celled, 3— 5-lobed; aril orange or scarlet. 

 Capsule 2-celled, unlobed ; aril white or nearly so. 

 Fruit indehiscent, by abortion 1-seeded; aril wanting. 

 Stamens more numerous than the sepals or petals ; ovary 1-celled. 



1. CELASTRUS L. Waxwork, Shrubby Bittersweet, Staff-tree. 



1. C. scandens. 



2. EUONyMUS (Tourn.) L. Burning Bush, Wahoo. i. E. atropurpureus. 



3. PACHYSTIMA Raf. Mountain Lover. 



Leaves decussately spreading; petioles abruptly contracted into the midrib; petals 

 nearly as broad as long; stigma roxmded. 1. P. Myrsinites. 



Leaves arranged in one plane; petioles thickened, the thickening continued into the 

 midrib; stigma 2-lobed. 

 Stigma slightly 2-lobed; anthers equalling the filaments. 2. P. macrophylla. 



Stigmas deeply 2-cleft; anthers much shorter than the filaments. 3. P. Schaefferi. 



4. MORTONIA A. Gray. 



5. FORSELLESIA Greene. 

 Stamens 5-7. 



Stamens 10. 



I. i\/. uiahensis. 



1. F. meionandra. 



2. F. spinescens. 



Family 77. ANACHARDIACEAE. Sumach Family. 



Drupe with pubescent exocarp ; stone smooth. 

 Drupe with glabrous, smooth exocarp ; stone ribbed. 



1. RHUS (Tourn.) L. Sumach, Skunk-bush. 



Leaflets 11-21; inflorescence terminating leafy shoots. 



Leaflets light green or yellowish green, rather dull, subsessile. 

 Leaflets dark green above, shining, strictly sessile. 

 ' Leaflets 1-3, rarely 5 ; inflorescence axillary. 

 Leaves densely villous. 

 Leaves puberuleut or glabrous. 



Leaves 3-foUolate, rarely 5-foUolate. 



Branchlets and leaves puberulent, at least when young. 



Branchlets and leaves glabrous, 

 and veins. 



1. Rhus. 



2. Toxicodendron. 



1. R, cismontana. 



2. R. occidentalis. 



3. R. Osterhoutii. 



4. R. trilobata. 



except a few scattered cilia on the petioles 

 5. R. oxyacanthoides. 



