EXOGEN^E THALAMIFLORJE. 



109 



Hebradendron cambogioides. 1 . A female flower, with the sterile stamens sur- 

 rounding the pistil. 2. A male flower. 3. An anther, which opens by throwing off 

 a cap, in consequence of transverse dehiscence. 4. A transverse section of the ovary. 



33. Aceracea. Trees. Leaves opposite, without stipules. 

 Flowers small, green, often polygamous. Flowers unsym- 

 metrical. Calyx imbricated. Petals inserted round an hy- 

 pogynous disk. Stamens inserted upon an hypogynous disk, 

 generally 8. Ovary 2-lobed; style 1. Fruit of 2 parts, 

 which are samaroid ; each 1 -celled ; with one or two seeds ; 

 albumen none. 



USES. The saccharine sap of Acer saccharinum yields a 

 kind of sugar in North America. The timber of most species 

 is light, clean, and useful, where strength is not required. 



TYPICAL GENUS. Acer. 



34. ^Escnlaceee. Trees or shrubs. Leaves opposite, with- 

 out stipules, quinate or septenate. Racemes terminal. Flow- 

 ers large, showy. Flowers unsymmetrical. Calyx cam- 

 panulate, 5-lobed. Petals 4 or 5, unequal, hypogynous. 

 Stamens 7-8, unequal. Ovary 3-celled ; ovules 2 in each cell. 

 Fruit 1- 2- or 3-valved. Seeds large, with a broad hilum ; 

 albumen none ; embryo curved, germinating under ground. 



USES. Handsome trees or bushes. Seeds filled with starch, 

 which renders them nutritious ; but it is said that they are 

 also dangerous. 



TYPICAL GENUS. ^Esculus. 



