Carya Nutt.

Tutin, T. G., Heywood, V. H., Burges, N. A., Moore, D. M., Valentine, D. H., Walters, S. M. & Webb, D. A., 1964, Flora Europaea - Volume 1. Lycopodiaceae to Platanaceae, Cambridge University Press : 57

2. Carya Nutt. 1

Twigs with continuous pith. Buds with scales, sessile. Leaves not aromatic. Male catkins 3 or more together, many-flowered, pendent. Female flowers in 2- to 10-flowered terminal racemes. Fruit a large drupe; mesocarp dehiscing more or less completely into 4 valves. 1 Bud-scales 4-6, valvate, bright yellow; fruit 4-winged in upper half 1. cordiformis

1 Bud-scales 6-12, imbricate, not bright yellow; fruit unwinged or slightly winged near apex

2 Bark not scaling; buds 8-12 mm; fruit slightly winged near apex 2. glabra

2 Bark scaling; buds 13-25 mm; fruit unwinged 3. alba