Juglans microcarpa aka Texas Walnut

Juglans microcarpa is a deciduous tree in the walnut family. Its common names include little walnut and Texas walnut. It grows from New Mexico to southern Kansas and northeastern Mexico. Its range also includes Oklahoma and Texas. It grows beside streams on limestone banks and in valleys. It also occurs in dry, rocky ravines within this range.

The plant forms a large shrub or small tree. It often branches near the ground into several trunks. Its broad, rounded crown gives shade and attracts birds. Garden size is around 30–33 feet (9–10 metres) tall and wide. Oregon State gives a wider height range of 20–50 feet (6–15 metres). Gray bark darkens and forms deep cracks with age. Green young twigs turn gray-brown and carry fuzzy, pale brown buds. The brown pith has chambers.

The leaves grow in an alternate pattern along the stems. Each pinnate leaf has narrow leaflets with fine teeth. Sources report seven to 21 leaflets per leaf. The upper leaf surface is green, with a paler underside. Crushed leaves give off a scent. Leaves turn yellow in fall. Male and female flowers grow on the same tree. Male flowers hang in yellow-green catkins on older twigs. Small female flowers sit in clusters at branch tips. Wind carries the pollen, and the tree can fertilize itself. Reported bloom dates span March through June.

The round fruits ripen in fall, with seeds maturing from October through December. Each fruit measures less than an inch across. Its thin husk turns from yellow-green to brown. A thick, deeply grooved shell surrounds a small edible seed. The raw kernel tastes sweet and contains oil. People can extract edible oil, but it soon turns rancid. Plants For A Future lists no known hazards or medicinal uses. The small kernel and thick shell limit its food value.

Choose a sunny spot with shelter from strong winds. Chicago Botanic Garden also lists partial shade. Deep, well-drained loam suits it, though it accepts sand and clay. It prefers moist soil but withstands drought and strong heat. Slightly alkaline soil suits it, though mildly acid soil also works. Chicago lists USDA zones 6–8; Oregon State lists zone 7. Young trees need winter protection and dislike root disturbance. Brief frost can damage flowers and new shoots. Leaf chemicals can slow the growth of plants beneath it. Uses include rootstock, veneer, cabinets, and furniture. Heavy cutting for veneer has affected wild trees.