MAPLE FAMILY 553 



beneath, 4-8 cm. long, 5-10 cm. wide; lobes rhombic-lanceolate; hypanthium 

 long-hairy; samaras divergent, about 3 cm. long, forming with each other an 

 angle of about 120. Canons: w Tex. Wyo. Ida. Ariz. Son. Submont. 

 Ap-My. 



2. NEGUNDO (Ray) Ludwig. BOX-ELDER, ASH-LEAVED MAPLE. 



Trees, with light green twigs, widely branching. Leaves opposite, odd-pin- 

 nate, usually with toothed leaflets. Flowers dioecious, appearing before the 

 leaves, the staminate in drooping small clusters, the pistillate racemose. Sepals 

 4 or 5, very small. Petals wanting. Stamens 4 or 5. Disk obsolete. Samaras 

 2, with reticulate wings. [Rulac Adans.] 



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

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



Branchlets 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. 



1. N. Nuttallii (Nieuwl.) Rydb. Tree up to 15 m. high, with spreading 

 branches; bark of the twigs and younger branches light green; leaflets usually 3, 

 lanceolate or ovate, long-acuminate, usually rounded at the base, coarsely 

 toothed or often more or less lobed, sparingly hairy or in age glabrate above, 

 more densely so beneath, and often with tufts of hairs in the axils of the veins; 

 fruit glabrous, gradually tapering below; wing scarcely decurrent. River valleys: 

 Mich. la. Kans. Colo. Mont.; often cultivated. Plain. Ap-My. 



2. N. interius (Britton) Rydb. Tree up to 12 m. high; leaflets lanceolate 

 or ovate, or the terminal rhombic, 5-12 cm. long, long-acuminate, usually lobed, 

 coarsely toothed, otherwise as in the preceding; fruit as in the preceding. A. 

 interior Britton. Along streams and in canons, mostly in the foot-hills and moun- 

 tains: Sask. Man. Neb. N.M. Ariz. Mont. Plain Submont. My-Je. 



3. N. Kingii (Britton) Rydb. Tree perhaps 10 m. high; twigs grayish 

 green; leaflets lanceolate, long-acuminate, 5-10 cm. long; pubescence as in the 

 preceding; fruit glabrous; wings less spreading than in the two preceding. A. 

 Kingii Britton. Canons: Utah (? Ariz.). Submont. Mont. My-Je. 



FAMILY 79. RHAMNACEAE. BUCKTHORN FAMILY. 



Shrubs or trees, with alternate, rarely opposite, simple, usually several- 

 ribbed leaves and small stipules. Flowers greenish, perfect or polygamous, 

 rarely dioecious. Sepals 4 or 5, valvate. Hypanthium somewhat developed, 

 lined or filled with a thickened disk. Petals 4 or 5. Stamens of the same 

 number, inserted on the disk, opposite the petals. Gynoecium of 2 or 3 

 united carpels; ovary 2- or 3-celled, partly immersed in the disk. Styles 

 and stigmas more or less united. Fruit a capsule, a drupe, or rarely a samara. 



Fruit pulpy; petals small, clawless, or wanting; stigmas usually 2. 1. RHAMNUS. 



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



1. RHAMNUS (Tourn.) L. BUCKTHORN. 



Shrubs or trees, unarmed, or with spinose branchlets. Leaves alternate, 

 entire or toothed, several-ribbed; stipules deciduous. Flowers perfect or poly- 

 gamo-dioecious, axillary, often clustered, in racemes, cymes or umbels. Sepals 

 4 or 5, keeled within. Disk cup-shaped, lining the hypanthium. Petals 4 or 5, 

 or wanting, clawless, inserted on the margin of the disk. Stamens of the same 

 number, on the edge of the disk; filaments very short. Ovary 2-4-celled; styles 

 2-4, united at the base. Drupe berry-like, with 3-4 nutlets. Endosperm fleshy. 



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

 buds scaly. 

 Shrub spinose; introduced species. 1- R- carthartica. 



