170 DE CANDOLLE'S SYSTEM. 



152. Juglandacea. Trees. Leaves alternate, pinnated, 

 without pellucid dots or stipules. Flowers unisexual, amen- 

 taceous. Calyx in the males membranous ; in the females 

 superior. Petals in the males ; in the females occasionally 

 present. Stamens indefinite. Ovary inferior, incompletely 

 2- 4-celled ; ovule solitary, erect. Fruit drupaceous, 1-celled, 

 with 4 imperfect partitions. Seed 4-lobed ; radicle superior. 



USES. Trees furnishing excellent timber ; that of Juglans 

 regia and nigra is used for gunstocks ; of Carya alba for pur- 

 poses of elasticity and strength : the former are Walnuts, the 

 latter Hickory. The fruit is purgative ; that of the common 

 Walnut when young, made into a preserve with the husk, is 

 a domestic medicine ; and Juglans cathartica derives its name 

 from its quality. 



TYPICAL GENUS. Juglans. 



1 53. Cycadacea. Trees, with a cylindrical trunk, increasing 

 by a single terminal bud. Leaves pinnated, gyrate. Flowers 

 dioBcious. Males monandrous, in cones. Females either in 

 cones, or in the form of contracted leaves. Ovules solitary, 

 naked. Embryo in the midst of albumen, hanging by a 

 spiral suspensor. 



USES. A bitter gum of unknown use exudes from the 

 trunk when wounded ; the latter contains a great quantity of 

 starch, which forms a kind of arrow-root extracted from 

 Zamias in the West Indies, and a sort of Sago from the 

 species of Cycas. 



TYPICAL GENERA. Zamia, Cycas. 



154. Taxace/e. Trees with continuous branches. Ligne- 

 ous tissue marked with circular disks. Leaves usually en- 

 tire ; sometimes dilated and lobed, and in those cases having 

 forked veins. Flowers mono3cious or direcious, solitary. Fi- 

 laments monadelphous. Females ; ovules naked, their outer 

 skin becoming hard. Seed hard, either naked or surrounded 

 by a succulent cup. Albumen fleshy. Embryo dicotyledon- 

 ous. 



USES. The Yew and several others are valuable timber- 

 trees. The leaves of Yew are foetid and deleterious ; they 

 are said to act medicinally like Digitalis without accumulating 



