Carya illinoinensis aka Pecan

Carya illinoinensis, or pecan, is a large tree in the walnut family. It sheds its leaves each fall. Its native range spans the central and east-central United States into Mexico. It grows in rich bottomlands and along streams and rivers. Pecan is the largest of the hickories. Gardens need ample space for its trunk and spreading crown. It suits large grounds, woodland edges, and sites needing shade.

Garden trees reach 70–100 feet (21.3–30.5 metres) tall. Their crowns can spread 40–75 feet (12.2–22.9 metres) wide. Some trees reach 150 feet (45.7 metres). Large limbs rise from the trunk, then spread outward. Lower limbs on old trees may sweep toward the ground. The grey-brown bark has grooves that form rough rectangular blocks. Brown twigs bear raised lenticels and hairy buds. Alternate, pinnate leaves have 9–17 pointed leaflets with toothed edges. The green leaves turn yellow to yellow-brown in fall.

Small yellow-green flowers bloom in spring, with timing varying by location. Each tree bears both male and female flowers. Male flowers hang in catkins; female flowers form short spikes. Wind carries the pollen between trees. Different varieties improve nut set because flower timing can limit self-pollination. The green husk turns brown and splits into four parts. Sweet nuts ripen in fall. Birds and small mammals eat them. The tree also hosts luna moth and hickory horndevil larvae.

Pecan grows best in full sun and deep, moist soil. Good drainage matters, though it accepts clay, sand, and loam. It tolerates both acid and alkaline soils, plus drought. Sources place it in USDA zones 5–9. A deep taproot makes moving established trees hard. Seed-grown trees may need eight to ten years to bear nuts. Cool summers and late springs can reduce crops in northern sites. Late frosts can also cut yields. Brittle limbs may break in wind.

Scab can harm both the leaves and nuts. Other diseases include anthracnose, leaf spots, and powdery mildew. Aphids, weevils, stink bugs, twig girdlers, and webworms may cause damage. Pecan needs a medium level of care. People eat the kernels raw or cooked, including in baked foods. The seeds also yield edible oil and a milk substitute. PFAF reports leaf tea use and lists no known hazards. The wood serves as fuel and sometimes for tools and wagons.