ACEBACEAE (MAPLE FAMILY) 313 



1. Rhus cismontana Greene, Wash. Acad. Sci. 8: 189. 1906. Shrub 8-20 

 dm. high, with smooth, glabrous or glaucous branches: leaflets 9-17, sessile 

 or petiolulate, from broadly to narrowly lance-oblong, acute or acuminate, 

 serrate, pale green above, lighter beneath and often glaucous, moderately 

 firm: panicle dense, generally pyramidal: drupelets spherical to ovate, pubes- 

 cent with acid reddish hairs; stone smooth. R. glabra. (R. nitens, R. tessel- 

 lata, R. albida, and R. asplenifolia Greene, and possibly others of the species 

 proposed in the paper cited above.) From Dakota and Utah to New Mexico 

 and Arizona. 



2. Rhus Rydbergii Small, Mem. N. Y. Bot. Gard. 1: 268. 1900. A single- 

 stemmed shrub, less than 1 m. high: petioles 6-12 cm. long; leaflets 3-10 cm. 

 long, broadly ovate, often somewhat rhomboid, glabrous except on the prom- 

 inent veins beneath, sinuately toothed: flowers in small, conical, axillary pan- 

 icles: petals ovate, 3 mm. long, yellowish streaked with green: fruit globular, 

 about 6 mm. in diameter, white and shining when ripe. R. Toxicodendron in 

 part. WESTERN POISON IVY. Poisonous to the touch. Open woods; in the 

 mountains and extending eastward to the plains. 



3. Rhus trilobata Nutt. T. & G. Fl. N. A. 1: 219. 1838. A diffusely 

 branched shrub, 6-16 dm. high, ill-scented: leaflets cuneate-oboyate or rhom- 

 boidal, crenately toothed or lobed above the middle, sometimes 3-lobed: 

 flowers in scaly-bracted ; spike-like catkins, yellowish, preceding the leaves: 

 fruits globose, red, viscid-pubescent. R. aromatica trilobata. SKUNK-BUSH. 

 Not poisonous. Common on bleak hillsides; throughout our range. 



68. CELASTRACEAE Lindl. STAFF TREE FAMILY 



Shrubs with simple leaves, no stipules, and small, dull-colored, perfect, reg- 

 ular flowers. Sepals and petals imbricated. Stamens as many as the petals, 

 alternate with them and inserted on the margin of a broad disk which lines 

 the calyx-tube. Seeds arillate. 



1. PACHYSTIMA Raf. 



Low evergreen shrubs, with smooth, opposite, short-petioled, serrulate leaves. 

 Flowers solitary or in few-flowered axillary cymes. Calyx with a short tube 

 and 4 rounded lobes. Petals 4. Ovary free, 2-celled; style very short. Cap- 

 sule small, coriaceous, 1-2-seeded. Seeds inclosed in a white many-cleft 

 membranaceous aril. 



1. Pachystima myrsinites Raf. Am. Month. Mag. 1818. Leaves ovate to 

 oblong or oblanceolate, cuneate at base: fruit smooth. In the mountains; 

 from New Mexico to British America and west to California. 



69. ACERACEAE St. Hil. MAPLE FAMILY 



Trees or shrubs, with watery saccharine sap and opposite palmately lobed 

 or more rarely compound leaves. Flowers polygamous or dioecious, in lateral 

 or terminal umbel-like corymbs or fascicles. Calyx imbricate, 5-parted. 

 Petals 5 or wanting, inserted around the hypogynous disk. Ovary 2-lobed, 

 its 2 styles inserted between the lobes. Fruit of 2 long-winged samaras joined 

 at the base. 



ACER L. MAPLE 



Flowers in umbel-like corymbs. Calyx colored, usually 5-lobed. Petals 

 5 or none. Stamens usually 8. Fruit Divaricately 2-winged above, separable 

 at maturity, each 1-seeded, 



