Carya glabra (Mill.) Sweet

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Article from Bean's Trees and Shrubs Hardy in the British Isles

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'Carya glabra' from the website Trees and Shrubs Online ( Accessed 2019-11-18.


Common Names

  • Pignut Hickory


  • Juglans glabra Mill.
  • C. porcina Nutt.
  • C. ovalis (Wangenheim) Sarg.


Cone. Used here to indicate male pollen-producing structure in conifers which may or may not be cone-shaped.
(sect.) Subdivision of a genus.


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Article from Bean's Trees and Shrubs Hardy in the British Isles

Recommended citation
'Carya glabra' from the website Trees and Shrubs Online ( Accessed 2019-11-18.

Tree to 30 m. Bark light grey, smooth or fissured or exfoliating in plate-like scales or strips. . Branchlets reddish brown, slender, virtually glabrous or sparsely scaly. Terminal bud ovoid, 0.5–1.5 cm long, reddish brown to tan; bud scales imbricate, scaly, glabrous to pubescent. Leaves deciduous, imparipinnate, 20–30 cm long; leaflets (three to) five to seven (to nine), ovate to obovate or elliptic, 4–21 × 2–10 cm, upper surface largely glabrous, scaly when young; lower surface glabrous to pubescent with unicellular and 2-4-armed hairs, large peltate scales and small irregular, round and 4-lobed peltate scales at first, later glabrous; margins finely to coarsely serrate, apex acuminate to narrowly acuminate; lateral petiolules 0–0.1 cm long, terminal petiolules 2–1.8 cm; petiole and rachis glabrous to pubescent; petiole 3–14 cm long. Staminate spikes to 13 cm long, glabrous or pubescent. Fruits pale to reddish brown, 2–4.5 × 2–3.5 cm, obovoid to globose, splitting to the middle or base; nuts compressed or not. Bean 1970. Stone & Whittemore 1997, Whittemore 2013.

Distribution  Canada Ontario United States Alabama, Arkansas, Connecticut, Delaware, District of Columbia, Florida, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Massachusetts, Michigan, Mississippi, Missouri, New Hampshire, New Jersey, New York, North Carolina, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, Tennessee, Texas, Vermont, Virginia, West Virginia

USDA Hardiness Zone 5

The taxonomic treatment of Carya glabra and its close relatives has been debated in the United States for well over 100 years, the question being whether to treat C. ovalis as a distinct species or as part of C. glabra. Opinion has swayed both ways and Manning (1950) found the extremes so different that he treated them as separate, whilst acknowledging that intermediates are also frequent. He also noted that the two favour different conditions in the wild, with C. glabra more frequent along valleys and streams and C. ovalis more often found in dry upland sites, though ecological variation is found in other members of the genus, for example C. ovata and C. cordiformis.

Lance (2004) also treats the two as separate species, though acknowledging that the distinction is arguable and describing Carya glabra as ‘variable’, listing characters exhibiting this variation as those of numbers of leaflets, leaf size, leaf pubescence and husk thickness. This author states that the differences found in typical C. ovalis include having typically 7 leaflets, reddish petioles, stouter twigs, fruits not pear shaped, all or some husks splitting to the base and the husk being slightly winged. C. ovalis is also treated by some authors as C. glabra var. odorata

Stone and Whittemore (1997) include C. ovalis as part of C. glabra, not recognising it at varietal rank, describing it as a ‘highly polymorphic species’ which intergrades, and this treatment is adopted here. These authors also note the ecological variation found within it and state that intergradation also occurs with C . floridana, C . pallida and C . texana. It also apparently hybridizes with C . cordiformis to form C. × demareei.

Cultivated in The United States since 1750 (Kurz 2003) and introduced to Britain in 1799 (Bean 1970), there are many fine mature examples of C. glabra in gardens which colour exceptionally well in autumn. The UK champion, growing at Warnham Court, West Sussex, was measured at 26.5 m tall in 2017 (TROBI 2018). Consistent with other ‘true’ hickories, members of section Carya, the species is slow to establish… Measurements to follow


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