Edwards’s Bot. Reg. 20: plate 1686. 1834.
Shrubs or trees. Leaves: blade flat to concave-convex, coriaceous, margins entire, flat, revolute, or strongly undulate. Inflorescences axillary, aments; bracts opposite, distinct or connate basally; bracteoles 0. Pedicels: staminate present, pistillate absent. Staminate flowers: sepals 4, valvate in bud, apically connivent by intertwined hairs, linear to lanceolate-oblong; petals 0; nectary absent or vestigial; stamens alternate with sepals, anthers basifixed. Pistillate flowers: sepals 2, sometimes rudimentary; petals 0; nectary absent; ovules 2; styles 2(–3), erect or recurved, linear-lanceolate; stigmas decurrent on adaxial surfaces of styles. Fruits berries, dark blue to black, drying whitish-gray, subglobose to ovoid, fleshy, becoming brittle. Seeds (1–)2 per fruit. x = 11.
w, sc United States, Mexico, West Indies (Cuba, Hispaniola, Jamaica), Central America, some cultivated.
Species 17 (8 in the flora).
Two sections of Garrya have been recognized (see key below). Species of sect. Garrya range from Washington to Baja California and New Mexico, with one outlier in Guatemala, G. corvorum Standley & Steyermark. Section Fadyenia de Candolle ranges from trans-Pecos Texas to Arizona and from Mexico (including Baja California) to Central America plus the West Indies (Cuba, Hispaniola, and Jamaica). In addition to the features noted in the key, in sect. Garrya pistillate flowers bear a pair of small appendages at the ovary apex near the style base, whereas in sect. Fadyenia pistillate flowers occasionally produce two foliaceous bracts partially adnate to the ovary. The phylogenetic distinction between the two sections has been confirmed by D. O. Burge (2011).
The staminate flowers in pendulous aments of Garrya are similar to those in other genera specialized for wind-pollination. The staminate aments are more flexible than the pistillate and more responsive to wind currents. P. A. Munz (1959) noted that in California many of the species intergrade extensively where their distributions overlap, and hybridization and intraspecific variation underlie continuing uncertainty about delimitations of taxa. Natural hybrids, however, have not been reported elsewhere. The artificial hybrids G. ×issaquahensis Talbot de Malahide ex E. C. Nelson (G. elliptica × G. fremontii) and G. ×thuretii Carrière (G. elliptica × G. fadyenii Hooker) have been bred for garden planting.
The common name silktassel alludes to the sericeous vestiture of the long, showy aments in sect. Garrya. Plants are cultivated mainly for the foliage and showy staminate aments, and cultivars are mostly staminate plants propagated from cuttings.
Stem extracts of Garrya laurifolia Bentham are toxic but are used as an antidiarrhetic throughout rural Mexico, and bark extracts were reportedly used by Native Americans to treat fever (G. V. Dahling 1978).
|1||Staminate aments 1–3 cm; pistillate aments loose, internodes 4+ mm, erect, sometimes branched; pistillate bracts distinct or connate basally, each usually subtending 1 flower, at least proximal similar in size and shape to distal leaves; Arizona, New Mexico, Texas [Garrya sect. Fadyenia].||> 2|
|2||Leaf blade abaxial surfaces glabrous or sparsely strigose.||Garrya wrightii|
|2||Leaf blade abaxial surfaces persistently sparsely to densely puberulent-tomentulose to tomentulose with coiling to recurved hairs.||> 3|
|3||Leaf blades 1.6–4(–5.5) × 0.7–2.5 cm, margins undulate, ± muricate-roughened, especially distal to middle, adaxial surfaces usually persistently tomentose, sometimes ± glabrescent.||Garrya goldmanii|
|3||Leaf blades 4.5–8 × 2.5–5 cm, margins flat, smooth, adaxial surfaces glabrate or glabrous.||Garrya lindheimeri|
|1||Staminate aments 3–20 cm; pistillate aments compact, internodes to 1 mm, pendulous, unbranched; pistillate bracts connate proximally into deep cup, at least at proximal nodes each subtending 3 flowers, differing in size and shape from leaves; Arizona, California, Nevada, New Mexico, Oregon, Utah, Washington [Garrya sect. Garrya].||> 4|
|4||Leaf blade abaxial surfaces usually densely, sometimes becoming sparsely, closely tomentose, hairs curled or crisped, interwoven.||> 5|
|5||Leaf blade apices rounded to obtuse; pistillate and staminate aments 8–15 cm.||Garrya elliptica|
|5||Leaf blade apices acuminate; pistillate and staminate aments 2.5–7 cm.||Garrya veatchii|
|4||Leaf blade abaxial surfaces glabrous, glabrate, or sparsely to densely strigose-sericeous or strigose, hairs antrorsely appressed.||> 6|
|6||Leaf blades abaxially whitish, adaxially yellow-green to gray-green, dull; berries densely strigose-sericeous, sometimes glabrate toward base.||Garrya flavescens|
|6||Leaf blades abaxially green, adaxially bright to olive green, glossy; berries glabrous, glabrate, or sparsely strigose near apex.||> 7|
|7||Staminate aments 7–20 cm; leaf blade abaxial surfaces glabrous or sparsely strigose.||Garrya fremontii|
|7||Staminate aments 5–7 cm; leaf blade abaxial surfaces densely strigose-sericeous.||Garrya buxifolia|