Northern Ontario Plant Database
Carya cordiformis (Wangenh.) K.Koch
En: bitternut hickory, swamp hickory, yellowbud hickory
Juglandaceae (Walnut Family)
General: A medium-size, deciduous tree, to 25 m tall, aromatic. Bark grayish; smooth when young, furrowed with age. Twigs smooth to slightly hairy, buds bright yellow, rough-textured (scurfy), bud scales 2, meeting at their edges (valvate); leaf scars large, oval and 3-lobed, with 3 nearly circular clusters of bundle trace scars.
Leaves: Alternate, pinnately compound with 7 to 9 leaflets, rarely 5 or 11. The upper 3 leaflets (including the terminal leaflet) are the largest. Leaflet blades are elliptic to lanceolate, 10–15 cm long, sessile, and curved slightly backward (barely falcate); leaflets are dark green above, paler and slightly hairy beneath; bases of leaflets tapering (cuneate) to rounded, apices pointed to sharply pointed (acute to acuminate), margins toothed (serrate).
Flowers: Unisexual, with male and female flowers on the same tree (plants monoecious); male flowers arranged in clusters of 3 elongate, drooping catkins (aments), borne laterally from the top of the previous-year's growth. Female flowers 2–10 in a terminal spike. Calyx reduced (absent in female flowers), petals lacking; male flowers with 4 stamens; female flowers with a single pistil subtended by a 4-lobed bract (involucre), which develops into the husk of the fruit.
Fruit: the large nearly globose to obovoid fruit, 2.5–3.5 cm long, is technically called a tryma – a drupe with a dehiscent husk. The thin green husk bears 4 raised ridges, through which it splits halfway to the base into four segments, revealing a pale grayish-brown, thin-shelled nut, 1.5–3 cm long, with a slender, pointed beak. The hard shell surrounds a bitter kernel (the seed).
Habitat and Range: dry to moist woodlands, streambanks, swamps. The bitternut hickory is a temperate, eastern North American species that occurs in some southern and eastern Ontario locations, but is absent from northern Ontario.
Internet Images: The Carya cordiformis webpage from the Trees of Wisconsin website. Click on the smaller images to view larger, more detailed photos.
See also the Carya cordiformis webpage from the Virginia Tech Dendrology website and the Carya cordiformis webpage from the USDA Silvics of North America website.
Similar Species: There are 3 species of hickory native to Ontario, but only Carya ovata, found in southern and eastern Ontario, has a range similar to that of Carya cordiformis. The third species, Carya glabra, is restricted to southernmost Ontario. If buds are present, it is easy to distinguish the valvate, bright yellow buds of Carya cordiformis from the other Carya species, which have ovate buds with overlapping (imbricate) brown scales. In addition to the characters listed below, Carya ovata can be distinguished from the other species by its shaggy bark, which splits into long, narrow plates that are attached at the middle and free at both ends.
See the Carya ovata (shagbark hickory) webpage from the Trees of Wisconsin website. Click on the smaller images to view larger, more detailed photos.
Compare the webpages of Carya glabra and Carya ovata from the Virginia Dendrology website.
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