[2][3] Castanea seguinii are small trees or shrubs, rarely reaching 12 m. Their stipules are narrowly lanceolate, 0.7 to 1.5 cm long, and are shed (become deciduous) when the plant is in fruit.

Leaves are 6 to 14 cm long, with their abaxial sides covered with yellowish‑brown to gray scaly glands, and have sparse hairs along the veins when young.

Leaf blades are oblong‑obovate to elliptic‑oblong in shape, with bases rounded or infrequently subcordate, but cuneate when young, with acuminate apices.

Cupules are 3 to 5 cm wide, and covered with sparsely pilose spiny bracts which are 6 to 10 mm long.

[3] Its nuts are small, but are edible and occasionally cultivated or collected in the wild and consumed by locals.