39. Kerria de Candolle, Trans. Linn. Soc. London. 12: 156. 1818.
[For William Kerr, d. 1814, collector in the far east, sponsored by Royal Botanic Gardens, Kew, and superintendent of Botanic Garden, Peradinaya, Sri Lanka]
James Henrickson, Alan S. Weakley
Shrubs, ˂spreading˃, open, rounded, 10–20(–30) dm; ˂rhizomatous, suckering freely˃. Stems 1–30+, widely arcuate, ˂sparingly branched˃; bark (periderm) not forming, epidermis green, ˂striate, glabrous˃; short shoots absent; unarmed; ˂bud scales imbricate˃. Leaves winter-deciduous, cauline, alternate; stipules caducous, linear-subulate, ˂thin˃, margins entire ˂± strigose-ciliate˃; petiole present; blade ovate to lance-ovate, 2–8.5 cm, membranous, margins flat, coarsely doubly serrate, abaxial surface sparsely sericeous-strigose along veins. Inflorescences terminal ˂on vernal, leaf-bearing lateral branches˃, flowers solitary, sparsely strigose or glabrous; bracts absent; bracteoles absent or present, ˂leaflike˃. Pedicels present. Flowers 20–50 mm diam.; epicalyx bractlets 0; hypanthium saucer-shaped, 3–4 mm diam., glabrous; sepals (4 or)5(or 6), spreading to reflexed, oblong-ovate to ± orbiculate; petals (4 or)5(or 6), to 34 in multi-petaled cultivars, ˂spreading˃, strong yellow to slightly orangish or yellow-cream (some petals white in multi-petaled cultivars), oblong-ovate to orbiculate, ˂base short-clawed, apex rounded to emarginate˃; stamens 80–130 (0 or few in multi-petaled cultivars), shorter than petals; torus absent; carpels (4–)5(–8), ˂globose˃, glabrous, styles lateral, ˂linear, ± exceeding filaments˃; ovules 2. Fruits aggregated nutlets, (1–)5 in 1 whorl, tan, obliquely obovoid-globose, 4.5–5 mm, ˂with distinct adaxial ridge˃, glabrous except for coarse basal hypanthial hairs; hypanthium persistent; sepals persistent (withering), reflexed; ˂exocarp thin, wrinkled, mesocarp thin, dry, endocarp ± cartilaginous˃. x = 9.
Species 1: introduced; e Asia (China, Japan); introduced also in Europe.
Kerria is a distinctive mesophytic shrub, native to montane forests and valleys at 200–3000 m in China and Japan, now widely cultivated. Morphologically, it stands closest to Neviusia.