152 



EUPHORBIACEAE 



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 sliallow 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 



linear-lanceolate. 



Seeds prominently tubercled; gland of the involucre solitary 



lanceolate (linear-lanceolate only in one variety). 



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



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



leaf-blades linear or 



1. P. cuphusperma. 

 leaf-blades ovate to 



2. P. dcntata. 



Water Starwort Family. 



Family 75. CALLITRICHACEAE. 



1. CALLITRICHE L. W.\ter Starwort. 

 Characters of the family. 



Upper floating leaves obovate or spatulate, 3-nerved; flowers subtended by a pair of 



bracts. 1. C. paluslris. 



All leaves linear, 1-nerved; flowers bractless. 2. C. autumnalis. 



Family 76. CELASTRACEAE. Staff-tree Family. 



stamens as many as the petals and sepals. 



Fruit a loculicidal capsule; seeds with an aril. 



Slirubby vines, with alternate leaves; ovary free from the disk; aril crimson. 



1. Celastrus. 

 Shrubs, with opposite leaves; ovary immersed in the disk. 



Capsule 3-5-celled, 3-5-lobed; aril orange or scarlet. 2. EuojnrMUS. 



Cap.sule 2-celled, unlobed; aril wliite or nearly so. 3. Pachystima. 



Fruit indehiscent, by abortion 1-seeded; aril wanting. 4. ]MoRTOXlA. 



Stamens more numerous than the sepals or petals; ovary 1-celled. 5. Forsellesi.v 



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 rounded. 1. P. Myrsiniles. 



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

 midrib; stigma 2-lobed. 

 Stigma slightly 2-lobed; anthers equalling the filaments. 

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



4. MORTONIA A. Gray. 



5. FORSELLESIA Greene. 

 Stamens .5-7. 

 Stamens 10. 



2. P. macTophylla. 



3. P. Schaefferi. 



1. M. utahcnsis. 



1. F. meionandra. 



2. F. spinescens. 



Family 77. ANACHARDIACEAE. Sumach Family. 



1. Rhus. 



2. Toxicodendron. 



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 puberulent or glabrous. 



Leaves 3-foliolate, rarely 5-foliolate. 



Branclilets and leaves puberulent, at least when yoimg. 



Branclilets and leaves glabrous, except a few scattered cilia on the petioles 



and veins. 3. B. oxyacanthoides. 



cismonlana. 

 occidentalis. 



3. R. Ostcrhoutii. 



4. R. trilnbala. 



