226 CHINESE ECONOMIC TEEES 



The wood is soft and light. Useful as an ornamental tree on account 

 of its large attractive foliage and panicled fragrant yellow flowers. 



ACERACEAE 



Leaves opposite, simple, usually, but not always, palmately lobed, 

 rarely entire, or pinnately compound, without stipules. Flowers 

 dioecious or monoecious, perfect or polygamous, regular. Stamens 4-10, 

 usually 8. Ovary superior, 2 celled. Style 1. Stigma 2. Fruit, 2 long- 

 winged samaras joined at the base where the seeds are borne ; seeds 1 or 

 2 in each cell, exalbuminous; the cotyledons thin and folded. 



A family of 2 genera, one widely distributed throughout the northern 

 hemisphere, the other monotypic and confined to China. The samaroid 

 fruit and opposite, exstipulate leaves are characteristic of this family. 



KEY TO GENERA 



I. Nutlets encircled by a broad wing; leaves pinnate, with 9-15 

 leaflets Dipteronia. 



II. Nutlets with an elongated wing on one side, in pairs; leaves 

 simple or compound Acer. 



ACER 



Trees or shrubs with watery, often saccharine sap. Leaves mostly 

 deciduous, opposite, petiolate, simple, lobed or compound, with 3 to 5 

 leaflets. Inflorescence in racemes, fascicles or corymbs. Flowers dioe- 

 ciously or monoeciously polygamous, regular, small; calyx colored, 5 

 parted ; petals 5 or absent ; stamens usually 8 (4-10) ; styles 2 ; ovary 2 

 lobed, 2 celled, and with 2 ovules in each cell. Fruit 2 long winged 

 samaras united at the base where the seeds are borne. Seeds solitary by 

 abortion, rarely 2. 



About 100 species in Asia, Europe, N. America and Northern Africa. 

 Sixty or seventy species have been found in eastern Asia. Of these a 

 large number occur in China. The Maples are ornamental shrubs and 

 trees with handsome foliage turning to brilliant colors in the autumn. 

 Several species are valuable timber trees. One American species, Acer 



