Juglandaceae, the Walnut Family
Trees with alternate pinnately compound leaves and flowers in catkins.
| 1a. Leaflets 11-23; pith divided by partitions into chambers — 2. | |
| 1b. Leaflets 5-11; pith not partitioned (Hickory) — 3. | |
| 2a. Pith brown; bark with flat longitudinal ridges | Butternut, Juglans cinerea. |
| 2b. Pith cream-color; bark of trunk without flat ridges | Black Walnut, Juglans nigra. |
| 3a. Bark of the trunk essentially smooth, not deeply furrowed or shaggy — 4. | |
| 3b. Bark of the trunk deeply furrowed or shaggy — 6. | |
| 4a. Leaflets glabrous beneath; buds greenish — 5. | |
| 4b. Leaflets somewhat pubescent beneath; buds bright yellow | Bitter Nut, Carya cordiformis. |
| 5a. Twigs hairy | Small-fruited Hickory, Carya microcarpa. |
| 5b. Twigs smooth | Pignut Hickory, Carya glabra. |
| 6a. Twigs and leaves both pubescent — 7. | |
| 6b. Twigs nearly smooth; leaves smooth beneath | Shag-bark Hickory, Carya ovata. |
| 7a. Twigs brownish; buds densely hairy | Mocker-nut Hickory, Carya alba. |
| 7b. Twigs orange; buds very slightly hairy | King-nut Hickory, Carya laciniosa. |