THE CACTI Allied to the mangroves and the myrtles, but like the yuccas in some particulars, and in choosing desert regions to live in, are the cacti, two genera of which have tree-like species in the United States. The soft stems of these trees are storehouses of moisture, as are also the fleshy branches. All green surfaces perform the functions of leaves. The spiny processes are the character by which most people recognise a cactus. The flowers are large and showy, formed into a tube by many overlapping sepals and petals. The fruit is a fleshy, many-seeded berry. The tree cacti are found in desert regions near the boundary between the United States and Mexico.
Resinous, aromatic trees with hard wood. Leaves deciduous.
alternate, pinnately compound. Flowers moncecious: staminate lateral, in catkins ; pistillate terminal, in spikes, or solitary. Fruit, a bony nut enclosed in a spongy husk.
KeY TO GENERA AND SPECIES A. Pith of twigs chambered; husk not opening at maturity; nuts not smooth.
I. Genus JUGLANS, Linn.
B. Fruit elongated, clammy, in racemes; heart wood light broWn. (J. cinerea) BUTTERNUT BB. Fruit globular, not clammy; solitary or paired; heart wood dark brown.
C. Nuts deeply and irregularly ridged, large.
(J. nigra) BLACK WALNUT CC. Nuts deeply furrowed, small, thick shelled.