This section is from the book "The Standard Cyclopedia Of Horticulture Vol2", by L. H. Bailey. See also: Western Garden Book: More than 8,000 Plants - The Right Plants for Your Climate - Tips from Western Garden Experts.
(ancient Greek name of the Alder, transferred to this genus on account of the resemblance of the leaves). Clethraceae. White Alder. Shrubs or small trees grown for their handsome spikes of white fragrant flowers appearing in summer.
Leaves alternate, usually serrate, deciduous or persistent: flowers white, in terminal often panicled racemes; petals 5, erect; stamens 10: caps, splitting into 3 valves, many - seeded. -About 25 species in Amer., E. Asia, Madeira. Only a few hardy deciduous species are generally cultivated; valuable for their showy spikes of white fragrant flowers, appearing late in summer. They grow best in a moist, peaty or sandy soil. Prop, by seeds, sown in spring in pans in sandy and peaty soil, and by greenwood cuttings under glass, growing best if taken from forced plants in early spring and placed in slight bottom heat; also, increased by layers and by division of large plants. Handsome when forced under glass.
b. Racemes usually solitary; stamens pubescent.
Michx. Tall shrub or small tree, to 15 ft.: leaves petioled, oval or oblong, acuminate, rounded or narrowed at the base, sharply serrate, pubescent beneath at least on the veins, 3-7 in. long: racemes usually solitary, nodding; sepals acute; style glabrous. July-Sept. Alleghany Mts., Va. to Ga. L.B.C.15:1427.
bb. Racemes usually panicled.
c. The leaves with 7-10 pairs of veins, 1 1/2-4 in. long: sepals obtusish; stamens glabrous.
Lam. (C. alnifolia variety tomentosa, Michx.). Fig. 998. Shrub, 2-8 ft.: leaves short-petioled, obovate, acute or short-acuminate, cuneate, serrate usually above the middle, pubescent above, tomentose beneath, 2-4 in. long: racemes few or solitary; style pubescent. Aug., Sept. N. C. to Fla. and Ala. B.M. 3743. G.F. 4:65 (adapted in Fig. 998). R.H. 1912, p. 519.
Fig. 998. Clethra tomentosa. (X 1/2) a. Leaves deciduous: stamens exserted.
Linn. Sweet Pepperbush. Shrub, 3-10 ft.: leaves short-petioled, cuneate, obovate or oblong, sharply serrate, mostly glabrous or nearly so, 2-4 in. long: flowers fragrant, in erect, usually panicled racemes. July-Sept. Maine to Fla. M.D.G. 1890:65; 1903: 473,474. G. 26:63. J.H. III. 31:375. Em. 426. variety paniculata, Arb. Kew. (C. paniculata, Ait.). Leaves cuneate-lanceolate, less toothed, green and glabrous on both sides: racemes panicled. variety rosea, Rehd. With pinkish flowers
cc. The leaves with 10-15 pairs of veins, 3-6 in. long.
Sieb. & Zucc. (C. canescens, Authors, not Reinw.). Shrub or tree, to 30 ft.: branches glabrous: leaves petioled, cuneate, obovate or oblong-obovate, acuminate, sharply dentate-serrate, pubescent beneath at least on the veins, 3-6 in. long: racemes panicled; flowers fragrant; pedicels about as long as the flowers; sepals obtuse; filaments glabrous. July-Sept. E. Asia. Gt. 19:654.
Fargesii, Franch. Shrub, to 12 ft.: young branchlets tomentose or nearly glabrous: petioles 1/2-1 in. long: leaves oblong-ovate or elliptic-oblong, acuminate, broadly cuneate or rounded at base, sharply serrate, slightly pubescent beneath or nearly glabrous, 3-6 in. long: flowers white, in panicled racemes 5-7 in. long; sepals pointed; filaments hairy, style glabrous. Cent. China. -One of the most ornamental species on account of its very long racemes.
aa. Leaves evergreen: stamens included.
Ait. Shrub or small tree, to 20 ft.: leaves cuneate, narrow-elliptic, acuminate, serrate, almost glabrous, shining above, 3-4 in. long: racemes panicled; flowers fragrant. Aug. - Oct. Madeira. B.M. 1057. G.C. 111.52:100. J.H. III. 64:245. G.M. 49:97; 52:127. Gt. 52, p. 209. Gn. 76, p. 428. - It stands only a few degrees of frost.
C. monostachya, Rehd. & Wilson. Allied to C. Fargesii. Leaves cuneate, elliptic-oblong to oblong-lanceolate, glabrous or nearly so: racemes usually solitary; style appressed pilose. Cent. China. - C. quercifolia, Schlecht. Shrub: leaves obovate-oblong, tomentose beneath: racemes panicled. Mex. B.R. 28:23. - C. tinifblia, Swartz. Shrub: leaves oblong, entire, tomentose beneath: racemes panicled. Jamaica. - The last two are evergreen and hardy only in subtropi-regions. Alfred Rehder.