Description from Flora of China
Shrubs, deciduous or semi-evergreen. Winter buds exposed, ovoid-orbicular, small, with several pairs of scales. Leaves opposite, rarely 3- or 4-whorled, shortly petiolate with an interpetiolar line, estipulate. Leaf margin entire to dentate or crenate-serrate. Flowers axillary, paniculate, single or paired (flowers opening consecutively); paired flowers with 6 bracts (Abelia chinensis), single flowers with 4 bracts (A. uniflora and A. forrestii) at base of ovaries; bracts small and not accrescent. Sepals 2-5, spreading, narrowly oblong, elliptic, persistent. Corolla 5-lobed, funnelform or bilabiate, white, yellow, pink, or red. Corolla tube gibbous ventrally at base containing a nectary of dense glandular hairs (nectaria trichomalia). Stamens didynamous, adnate to corolla tube, included or exserted; anthers introrse. Ovary narrowly oblong, 3-locular, 2 locules with 2 series of sterile ovules, 1 locule with a single fertile ovule; style filiform; stigmas capitate, white and papillose. Fruit an oblong, leathery achene, crowned with persistent sepals. Seed subterete, testa membranous; endosperm fleshy.
- 3-4. Abelia uniflora species complex
Shrubs deciduous, to 4 m tall. Branches pubescent, occasionally glabrous. Leaves highly variable in shape and size, ovate, orbicular, or lanceolate, 1-8 × 0.5-3.5 cm, abaxially densely white pubescent at base of midvein and lateral veins, adaxially sparsely pubescent, base cuneate, margin subentire or remotely serrate, apex obtuse to acuminate. Flowers single and axillary, sometimes slightly paniculate. Calyx of 2 oblong to elliptic sepals, 10-15 mm, ca. 1/3 as long as corolla tube. Corolla white to purplish pink, bilabiate, 25-50 mm, gibbous at base of tube, 5-lobed, outside pubescent, inside villous on lip; upper lip 2-lobed; lower lip 3-lobed, bearded and with reticulate orange markings. Stamens 4, didynamous; filaments partially adnate to corolla tube. Ovary pubescent, with 4 ovate to lanceolate bracts at base; style ca. as long as corolla tube; stigmas capitate. Achene 6-15 mm, pubescent, crowned with 2 persistent and slightly enlarged sepals. Fl. Apr-Jun, fr. Aug-Oct.
● Thickets, forests; 200-2000 m. Fujian, Gansu, Guangxi, Guizhou, Henan, Hubei, Hunan, Shaanxi, Sichuan, Yunnan.
This species shows variation in leaf and sepal shape, ovary length, and corolla size. In the past, many species have been recognized as separate. A specimen collected in Guizhou (Simmons et al. 288) has been identified to show introgression from Abelia chinensis. This phenomenon, as well as possible polyploidy, renders the infraspecific classification of A. uniflora very unreliable.
Five species (including one cultivated hybrid): China, Japan; five species (three endemic, one cultivated hybrid) in China.