Ulmus rubra aka Slippery Elm

Ulmus rubra, or slippery elm, belongs to the elm family. It grows wild from southeastern Canada through central and eastern America. This tree loses its leaves each year and grows fast. Wild trees may live for about 200 years. It grows in woods, along streams, and on rocky slopes. Its garden height reaches about 70 feet [21.3 m]. Its crown can spread to 50 feet [15.2 m]. Some accounts report trees reaching 80 feet [24.4 m]. Branches rise or spread outward from a single trunk.

Gray bark has flat ridges with shallow grooves between them. The reddish inner bark feels slippery when moist. Young twigs have hairs, while buds look dark brown or black. Leaves grow in an alternate pattern along the twigs. Each simple leaf has an uneven base and double-toothed edges. Tiny hairs give the upper face a rough feel. The paler underside has hairs and clear, raised veins. Leaves turn dull yellow before they fall in autumn.

Small green and red flowers grow in tight groups. They bloom from March to April in the Chicago area. In North Carolina, bloom can start as early as February. The flowers offer little show in the garden. Each flat, winged fruit, called a samara, holds one seed. Fruits mature from March to May in North Carolina. Birds and squirrels eat the seeds and buds. Birds also nest among the leaves. Deer and rabbits eat twigs, and caterpillars feed on this tree.

Slippery elm grows best in sun and moist, rich loam. It also accepts light shade and clay loam. Good drainage matters, though the tree tolerates wet and dry sites. It can withstand drought and many urban growing conditions. Chicago lists it for USDA zones 3 through 9. It provides shade and suits naturalized sites away from homes. Heavy seed fall can cause litter and unwanted seedlings. Its coarse look and disease risks limit its landscape use. Nurseries seldom stock it.

Dutch elm disease can kill this tree; beetles spread the fungus. Other risks include wetwood, phloem necrosis, rots, and cankers. Borers, leaf miners, scale, and beetles can also attack it. People use its wood for lumber and its bark for fibre. Inner bark has a history of medicinal use in throat lozenges. Leaves, inner bark, and young fruits have recorded food uses. Ground inner bark can thicken soups or go into flour. PFAF warns that outer bark may cause miscarriage during pregnancy.