SUMACH FAMILY 153 



Leaves 1-foliolate. or rarely some of tliem 3-foliolate with small lateral leaflets 

 and a broad terminal one. 6. R. utafiensis. 



2. TOXICODENDRON (Tourn.) Mill. Poison Ivy, Poison Oak, 



Poison Sumach. 

 Leaflets thick, the terminal one decidedly longer than broad, its petiolule usually 1-2 cm. 



long; petals 3 mm. long. 1. T. Rydbergii. 



Leaflets thin, the terminal one nearly as broad as long, its petiolule 3-4 cm. long; petals 



2.5 mm. long. 2. T. longipcs. 



Family 78. ACERACEAE. Maple Family. 



Leaves palmately lobed or rarely palmatedly compound; flowers polygamous or perfect. 



I. Acer. 

 Leaves pinnately compound; flowers dioecious. 2. Negundo. 



1. ACER (Tourn.) L. Maple. 



Flowers in racemes or corymbs; petals and sepals both present; disk well developed; 

 lobes of the leaves toothed. 

 Flowers in long racemes, appearing after the leaves; leaves long-acuminate, with 



small lateral lobes; petals longer than the sepals. 1. .4. spicatum. 



Flowers corymbose, appearing with the leaves; leaves not long-acuminate, deeply 

 3-5-cleft; terminal lobe only slightly larger; petals and sepals greenish, sub- 

 equal. 

 Bark of the one-year-old branches grayish; leaves and their lobes acuminate, not 

 dotted beneath. 

 Sinuses between the leaf-lobes shallow, open; terminal lobe broadly triangular- 

 ovate. 2. .4. Douglasii. 

 Sinuses between the leaf-lobes deep and narrow; terminal lobe rhombic. 



3. A. glabrurn. 



Bark of the one-year-old branches wliite ; leaves and their lobes acute, not acum- 

 inate, with more or less numerous glandular red dots beneath. 



4. A. tripartilum. 

 Flowers in umbels, appearing with the leaves; petals lacking; lobes of the leaves sinuate. 



5. A. grandidentatum. 



2. NEGUNDO (Ray) Ludwig. Box-elder, Ash-leaved Maple. 



Branchlets glabrous, usually with a bloom; anthers acute, tapering into a tip one-half 

 to one-fourth mm. long. 1. N. Nuttallii. 



Branclilets pubescent; anthers obtuse, merely mucronate. 



Wings of the carpels terminal, scarcely at all decurrent on the body; racemes seldom 



over 1 dm. long in fruit. 2. N. interius. 



Wings of the carpels extending down on the inner side almost to the bottom of the 

 sinus; racemes in fruit 1.5-2 dm. long. 3. N. Kingii. 



Family 79. RHAMNACEAE. Buckthorn Family. 



Fruit pulpy; petals small, clawless, or wanting; stigmas usually 2. 1. Rh.^mnus. 



Fruit dry; petals hooded and long-clawed; stigmas 3. 2. Ceanothus 



1. RHAMNUS (Tourn.) L. Buckthorn. 



Flowers soUtary or in sessile umbels, usually polygamo-dioecious or dioecious; winter- 

 buds scaly. 

 Slirub spinose; introduced species. J. R. carthartica. 



Slirub not spmose; native species. 



Flowers 4-merous; petals present; seeds 2, grooved; leaves not strongly veiny. 

 Leaves broadly lanceolate, acuminate with a blunt apex. 2. R. lanceolala. 

 Leaves narrowly lanceolate, not aciiminate. 3. R. Smithii. 



Flowers 5-merous, apetalous; seeds 3, scarcely grooved; leaves strongly veiny. 



4. R. alnifnlia. 

 Flowers in peduncled umbels or corymbs, perfect; winter-buds not scaly, pubescent. 

 Peduncles longer than the pedicels ; leaves merely callous-denticulate. 5. R. Purshiana. 

 Peduncles shorter than the pedicels, sometimes almost none; leaves finely but dis- 

 tinctly serrate. 6. R. betulaefolia . 



2. CEANOTHUS L. New Jersey Tea, Mount.\in Laurel, Snow Brush, 



Deer Brush. 



Leaves alternate, thin, triple-nerved. 



Leaf-blades rounded-oval, often cordate at the base, closely glandular-dentate or 

 crenate. 

 Peduncles often naked from lateral buds; leaves sparingly pubescent beneath, 

 soon glabrate. 

 Leaves 3-6 cm. long; young branches long-hairy, soon glabrate. 



I. C. sanguineus. 

 Leaves 1-2.5 cm. long; young branches finely puberulent. 2. C. Martini. 

 Peduncles on leafy branches of the present season; leaves velutinous beneath. 



3. C. velutinus. 



