56 ACERACEAE 



leaflets 3-6 cm. long, broadly ovate, acutish, serrulate; petals 6-8 mm. long, a little longer than 

 the striate calyx-lobes ; capsule 3-5 cm. long, the carpels separating at the summit and some- 

 what spreading, dehiscent down the inner side of the free portion. 



Occasional in foothill canyons, Upper Sonoran Zone; western slopes of the Sierra Nevada from Siskiyou 

 County to Tulare County, California. Type locality: "Banks of St. Cloud [McCloud] River," Shasta County, 

 California. April-May. 



Family 87. ACERACEAE. 



Maple Family. 



Trees or shrubs, with watery, often saccharine sap, and opposite, simple and 

 palmately lobed, or pinnate leaves. Flowers polygamous or dioecious, regular, in 

 terminal or axillary corymbs or racemes. Calyx generally 5-parted, the lobes imbri- 

 cated. Petals of the same number as the calyx-lobes or none. Disk thick, annular, 

 lobed, sometimes obsolete. Stamens 4-12, often 8; filaments filiform. Ovary supe- 

 rior, 2-celled, 2-lobed ; styles 2, inserted between the lobes. Fruit of 2 long-winged 

 samaras, joined at the base, but usually separating before falling. Seeds 1 or some- 

 times 2 in a samara, compressed, ascending ; endosperm none ; cotyledons thin, 

 folded. 



A family of 2 genera and about 125 species, natives of the northern hemisphere. The second genus, 

 Dipteronia, of central Asia, differs from Acer in having the samara winged all around. 



1. Acer l. Sp. pi. 1055. 1753. 



Characters of the family. [The Latin name for the genus.] 



A genus of about 120 species, natives of the north temperate regions. Type species, Acer Pseudo-Platanus L. 



Leaves simple, palmately lobed; flowers polygamous; petals present. 



Flowers in many-flowered racemes; body of the samara hispid. 1. A. macrophyllum. 



Flowers in few-flowered corymbs; samaras glabrous. 



Leaves 3-5-lobed; samaras slightly spreading, the angle about 45 degrees. 



2. A. glabrum Douglasii. 



Leaves 7-9-lobed; samaras widely spreading, the angle nearly 180 degrees. 



3. A. circinatum. 



Leaves pinnate, with 3-5 leaflets; flowers dioecious; petals none; body of samara finely pubescent. 



4. A. Negundo californicum. 



1. Acer macrophyllum Pursh. Big-leaved or Oregon Maple. Fig. 3095. 



Acer macrophyllum Pursh, Fl. Amer. Sept. 1 : 267. 1814. 



Tall round-topped trees attaining a maximum height of about 30 m., the bark on old trunks 

 thick and furrowed. Leaves large, 10-25 cm. broad, deeply 3-5-parted, the lobes irregular, 

 coarsely toothed, soft pubescent when young, becoming glabrate above and puberulent beneath in 

 age ; flowers polygamous, perfect and staminate flowers mixed in the same raceme ; sepals and 

 petals rather broad, about equal in length; filaments pubescent at the base; body of the samara 

 with stiff tawny hairs, wings 2-4 cm. long, diverging at an acute angle. 



Stream banks, mainly Transition Zone; southern Alaska southward, west of the Cascade Mountains and 

 Sierra Nevada to southern California. Type locality: Cascades of the Columbia River. April-May. 



Greene (Leaflets Bot. Obs. 2:248-254. 1912.) has proposed several segregates, relying largely on the 

 lobing of the leaf for differentiating the species. 



2. Acer glabrum subsp. Douglasii (Hook.) Wesml. Dwarf or Mountain Maple. 



Fig. 3096. 



Acer Douglasii Hook. Lend. Journ. Bot. 6: 17. pi. 6. 1846. 



Acer glabrum subsp. Douglasii Wesml. Bull. Bot. Soc. Belg. 29: 46. 1890. 



Acer glabrum var. Douglasii Dippel, Handb. Laubh. 2: 438. 1892. 



Small tree, 3-10 m. high, with smooth gray bark. Leaves simple, orbicular in outline, 5-lobed, 

 the lobes acute, coarsely and sharply serrate, the terminal tooth acuminate, truncate or sub- 

 cordate at base, 5-10 cm. long, glabrous, dark green above, paler beneath; petioles slender; 

 flowers in small, few-flowered corymbs, polygamous ; sepals and petals similar, spatulate-oblong, 

 about 4 mm. long ; samaras diverging at an angle less than 45 degrees, glabrous, the wings about 

 2 cm. long. 



Stream banks and edges of meadows, Canadian Zone; Alaska to the Cascade Mountains, northern Oregon, 

 east to western Montana. Type locality: "Blue Mountains of Oregon." April-May. 



Typical Acer glabrum Torr. inhabits the Rocky Mountains region, and is somewhat intermediate between 

 the subspecies Douglasii and Torreyi. 



Acer glabrum var. Torreyi (Greene) Smiley, Univ. Calif. Pub. Bot. 9: 261. 1921. {Acer Torreyi Greene, 

 Pittonia 5: 2. 1902.) Low tree or usually shrubby. Leaves 2.5-4 cm. long, usually broader than long, mostly 

 3-lobed, or obscurely 5-lobed, the lobes acutish, serrate with acutish teeth, base of the blade subcordate. _ Mountain 

 meadows and streams, Canadian Zone; Sierra Nevada, California. Intermediate forms between this and the 



