404 



EXOGENOUS OR DICOTYLEDONOUS PLANTS. 



758. Ord, Malpighiaceae is a large tropical family (with one or 

 two representatives in Texas), which differs from Aceracea? in its 

 more symmetrical flowers, trimerous gynsecium, solitary ovules, 

 the want of a disk, and in the entire leaves, &c. 



759. Ord, AceraceSB (the Maple Family). Trees or shrubs, with 

 opposite leaves and no stipules. Flowers small, polygamous, reg- 

 ular, sometimes- perfect, in racemes, corymbs, or fascicles, often 

 preceding the leaves. Calyx mostly of five sepals, more or less 

 united. Petals as many as the sepals, or none. Stamens three to 

 twelve, seldom agreeing in number with the sepals, inserted on or 

 around a hypogynous disk. Ovary of two more or less united 

 carpels ; each carpel forming a samara in fruit. Ovules two in 

 each cell. Seeds solitary, destitute of albumen. Embryo coiled. 

 Ex. Acer, the Maple ; useful timber-trees of northern temper- 



647 



ate regions. Sugar is yielded by the vernal sap of Acer saccha- 

 rinum, and in less quantity by A. dasycarpum and other species. 



FIG. 647. A branch of Acer dasycarpum (the White Soft Maple) with staminate flowers. 

 648. A separate, enlarged staminate flower. 649. Branch with pistillate flowers. 650. A sepa- 

 rate fertile flower; the bracts, &c., of the cluster cut away. 651. The same enlarged, with the 

 calyx cut away. 652. A cluster showing the fruiting ovaries expanding into wings (reduced in 

 size). 653. Ripe fruit; one of the samaras cut open to show the seed. 654. A leaf. 



