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Tree to 36 m in the wild. Bark dark grey, fissured or ridged, not exfoliating. Branchlets reddish brown, stout, hirsute and scaly. Terminal bud 0.5–1 cm long, tan (after early loss of outer scales). Leaves deciduous, imparipinnate, 20–30 cm long (up to 50 cm on vigorous, young trees); leaflets (five to) seven to nine, ovate to elliptic or obovate, 4–19 × 2–8 cm, upper surface hirsute along midrib and primary veins, puberulent with armed hairs and scales at first. Lower surface hirsute with 2-8-armed hairs, and with many large and small round peltate scales. margins finely to coarsely serrate, apex acute to acuminate; lateral petiolules 0–0.2 cm long, terminal petiolules 0.2–1.3 cm long ; petiole and rachis hirsute with large and small peltate scales; petiole 3–12 cm long. Staminate spikes to 14 cm long, hirsute, scaly. Fruits reddish brown, 3–4 × 2–3 cm, obovoid to globose, not compressed or compressed, splitting to the middle or nearly to base; nuts finely wrinkled. Stone & Whittemore 1997, Whittemore 2013.
Introduced to Britain in 1766 (Armitage et al. 2014), Bean (1970) described Carya tomentosa as ‘too much neglected’ in British gardens, though this has been somewhat rectified by a number of more recent introductions…
Like Carya laciniosa, the species has large winter buds, but its bark does not exfoliate. It also has particularly strongly fragrant foliage, which, like other members of the Juglandaceae, is strongest when the leaves are rubbed but Bean (1970) notes that on dewy, summer mornings it can be detected from some distance away.
The protologue of Juglans alba referred to the work of four authors, with three of these works referring to specimens of what is now Carya tomentosa and one, C. ovata.
Some authors refer to mockernut as Carya alba (e.g Lance 2004) though confusion surrounding this combination has now been resolved. As summarised by Stone and Whittemore (1997), both mockernut and shagbark hickory were at one point known as C. alba, based on Linnaeus’ Juglans alba. However, Rehder (1945) highlighted that Linnaeus’ protologue in fact referred to two taxa, C. tomentosa and C. ovata, and should be therefore rejected in favour of these names. Ward & Wiersema (2008) formally proposed the rejection of Juglans alba, which was recommended unanimously (Brummitt 2010).
A tree 50 to 60, occasionally 100 ft high; winter buds large, the terminal one broadly egg-shaped, pointed, 1⁄2 to 3⁄4 in. long, and 1⁄2 in. or more wide; the inner scales covered with a soft pale felt; young shoots very downy, especially at first. Leaves fragrant, 8 to 12 in. (on very vigorous young trees 20 in.) long; composed usually of seven (sometimes five or nine) leaflets; terminal leaflet is 5 to 8 in. long, 2 to 41⁄2 in. wide, obovate, wedge-shaped at the base; basal pair sometimes only 11⁄2 to 2 in. long, ovate, rounded at the base; the middle pair or pairs are intermediate in size and shape; all taper-pointed, toothed, upper surface dark green, downy on the midrib; lower surface yellowish, and covered with starry down and glands; common stalk stellately downy. Male catkins 3 to 5 in. long, very downy. Fruit top-shaped or roundish.
Native of eastern N. America; rare in cultivation. The species is distinct in its large winter buds (it is sometimes called ‘big-bud hickory’) and in the fragrance of its foliage. This, of course, is most marked when the leaf is rubbed, but on dewy mornings in summer it can be perceived many yards away from the tree. The mockernut has been too much neglected in gardens, if only on this account. There is a fine specimen at Kew 70 ft high, remarkable for its stately habit and splendid foliage. Another grows at Sidbury Manor, Devon; planted in 1898, it is 68 ft high. Smaller trees grow at Westonbirt and Tortworth, Glos.; and in the University Parks, Oxford. This species resembles C. cordiformis in its bark but is easily distinguished by its terminal winter buds, which are brown, hairy and broadly ovate, with imbricate scales; in C. cordiformis they are bright yellow, scurfy, elongated, with two pairs of scales which do not overlap (valvate).
specimens: Kew, in Ash Collection, pl. 1872, 75 × 51⁄2 ft (1978); University Parks, Oxford, 66 × 33⁄4 ft (1981); Warnham Court, Sussex, Old Nursery, 72 × 31⁄2 ft (1984).