(ancient Greek name). Betulaceae. Hazel. Filbert. Cobnut. Woody plants grown for their handsome rather large foliage and some species for their edible nuts.

Deciduous shrubs, rarely trees: leaves alternate, stipulate, petioled, serrate and usually more or less pubescent: flowers monoecious, appearing before the leaves; staminate in long, pendulous catkins, formed the previous year, and remaining naked during the winter (Fig. 1073), each bract bearing 4 divided stamens; pistillate included in a small, scaly bud with only the red styles protruding (Fig. 1074): fruit a nut, included or surrounded by a leafy involucre, usually in clusters at the end of short branches. - Fifteen species in N. Amer., Eu. and Asia, all mentioned below. Monograph by Winkler in Engler, Pflanzenreich, hft. 19, pp. 44-56 (1904), quoted below as Winkl.

Pistillate flowers of Corylus rostrata.

Fig. 1074. Pistillate flowers of Corylus rostrata. Natural size

Numerous varieties are cultivated in Europe for their edible nuts. They are also valuable for planting shrubberies, and thrive in almost any soil. The foliage of some species turns bright yellow or red in autumn. Propagated by seeds sown in fall, or stratified and sown in spring; the varieties usually by suckers, or by layers, put down in fall or spring; they will be rooted the following fall. Budding in summer is sometimes practiced for growing standard trees, and grafting in spring in the greenhouse for scarce varieties. They may also be increased by cuttings of mature wood taken off in fall kept during the winter in sand or moss in a cellar and planted in spring in a warm and sandy soil. Illustrated monograph of the cultivated varieties by Franz Goeschke, Die Haselnuss (1887). See, also, bulletin on Nut-culture by the U. S. Dept. of Agric. For the culture of the nuts, see articles Filberts and Hazels.

Winter catkins of filbert.

Fig. 1073. Winter catkins of filbert.

A. Husk or involucre consisting of 2 distinct bracts (sometimes partly connate).

B. Involucre densely spiny: leaves nearly glabrous.

1. Ferox, Wall

Tree, to 30 ft.: young branchlets silky-hairy: leaves oblong to obovate-oblong, usually rounded at the base, acuminate, doubly serrate, glabrous except on the veins beneath, with 12-14 pairs of veins, 3-5 in. long: involucre tomentose, forming a spiny bur about 1 1/2 in. across, longer than the small nuts. Himalayas. Winkl. 45. variety thibetica, Franch.

(C. thibetica, Batal.). Leaves broadly ovate to obovate: involucre glabrescent. Cent. and W. China. R.H. 1910:204.

bb. Involucre not spiny.

c. Bracts of the involucre deeply divided into linear lobes, much longer than the nut: tree.

2. Colurna, Linn

Tree, to 70 ft.: petioles 3/4-2 in. long, usually glabrescent: leaves deeply cordate, roundish ovate to obovate, slightly lobed and doubly crenate-serrate, at length nearly glabrous above, pubescent beneath, 3-5 in. long: fruits 3-10, clustered: involucre open at the apex, usually densely beset with glandular hairs: nut roundish ovate, 3/4in. long. From S. Eu. to Transcaspia. G.C. III. 40:256. Gn. 31, pp. 260-1. H.W. 2, p. 29. G.W. 14, p. 642. Gng. 16:163. - Ornamental tree, with regular pyramidal head, not quite hardy N. Rarely cultivated for the fruit under name of filbert or of Constantinople or Constantinople nut. variety glan-dulifera, DC. Petioles and peduncles glandular-setose: lobes of the involucre less acute and more dentate.

3. Chinensis, Franch

(C. Colurna variety chinensis, Burk.). Tree, to 120 ft.: petioles 1/3-1 in. long, pubescent and setulose: leaves ovate to ovate-oblong, cordate and very oblique at the base, glabrous above, pubescent on the veins beneath, doubly serrate, 4-7 in. long: fruit 4-6, clustered; involucre constricted above the nuts,, with recurved and more or less forked lobes, finely pubescent, not glandular. W. China. Winkl. 49 and 50.

cc. Bracts of the involucre divided into lanceolate or triangular lobes: shrubs.

D. The involucre not or only slightly longer than the nut, open or spreading at the apex. E. Lobes of bracts serrate or dentate.

4. Avellana, Linn

Shrub, to 15 ft.: leaves slightly cordate, roundish oval or broadly obovate, doubly serrate and often slightly lobed, at length nearly glabrous above, pubescent on the veins beneath: involucre shorter than the nut, deeply and irregularly incised: nut roundish ovate, 1/2-3/4in. high. Eu., N. Africa,W. Asia. H.W. 2:16, p. 28. variety atropurpurea, Kirchn. (variety fusco-rubra, Goeschke). Leaves purple. variety aurea, Kirchn. Leaves yellow. variety laciniata, Kirchn. (variety heterophylla, Loud.). Leaves laciniately incised or lobed. variety pendula, Goeschke. With pendulous branches. G.W. 2, p. 13. There are also many varieties cult, for their fruit

5. Pontica, Koch

Shrub: leaves cordate, roundish ovate or broad-oval, doubly serrate, pubescent beneath: involucre finely pubescent, with few glandular hairs at the base, campanulate, somewhat longer than the nut, with large spreading lobes: nut large, broad-ovate. W. Asia. F.S. 21:2223-4 (as C. Colurna). - From this species the cobnuts seem to have originated; also the Spanish nuts are probably mostly cross-breeds between this species and C. Avellana or C. maxima, or between the two latter species.

ee. Lobes of the bracts entire or sparingly dentate, triangular.

6. Heterophylla, Fisch

Shrub, to 12 ft.: petioles about 3/4in. long: leaves orbicular-obovate, cordate at the base, nearly truncate at the apex and with a very short point, incisely serrate, pubescent on the veins beneath, 2-4 in. long: involucre somewhat longer than the nuts, striate, glandular-setose near the base. Japan to W. China. S.I.F. 1:20. - Several varieties apparently not yet in cultivation occur in China: variety Crista-Galli, Burkill, variety setchueninsis, Franch., and variety yunnanensis, Franch.

dd. The involucre about twice as long as the nut, usually tightly inclosing the nut.

7. Americana, Walt

Shrub, 3-8 ft.: young branch-lets pubescent and glandular bristly: leaves slightly cordate or rounded at the base, broadly ovate or oval, irregularly serrate, sparingly pubescent above, finely tomentose beneath, 3-6 in. long: involucre compressed, exceeding the nut, the 2 bracts sometimes more or less connate, with rather short, irregular, toothed lobes: nut roundish ovate, about 1/2in. high. From Canada to Fla. west to Ont. and Dak. variety calyculata, Winkl. (C. calyculata, Dipp.). Involucre with 2 very large bracts at the base.

aa. Husk or involucre tubular, narrowed above the nut and forming an elongated beak.

B. Involucre finely pubescent outside with rather wide gradually narrowed beak.

8. Maxima, Mill. (C. Tubulosa, Willd.)

Shrub, sometimes small tree, to 30 ft.: leaves cordate, roundish-ovate, slightly lobed and doubly serrate, 3-6 in. long: involucre finely pubescent outside: nut oblong, large; kernel with thin red or white skin. S. Eu. H. W. 2, p. 30. Winkl. 49. variety purpurea, Rehd. (C. Avellana purpurea, Loud. C. maxima variety atropurpurea, Dochnahl). Leaves deep purplish red darker than in C. Avellana atropurpurea. F.E. 21:325. - Many varieties, with large nuts, known as filberts or Lambert's filberts. The cultivation forms are partly hybrids with C. Avellana.

bb. Involucre densely beset with bristly hairs, and usually rather abruptly constricted into a narrow beak.

c. Petioles usually longer than 1/2in.

9. Mandshurica, Maxim

(C. rostrata variety mands-churica, Regel). Shrub, to 15 ft.: young branchlets pubescent: leaves suborbicular to elliptic or obovate,

doubly serrate and slightly sinuately lobed, pubescent beneath, 3-5 in. long: involucre thickly beset with brown spreading bristles, about 2 in. long, about 3 times as long as the nut, divided at the the apex into narrow entire segments Manchuria, Korea. Winkl. 49.

10. Sieboldiana, Blume (C. Rostrata variety Sieboldiana, Maxim.)

Shrub, to 15 ft.: leaves elliptic to oblong or obovate, usually rounded at the base, doubly serrate and slightly lobed, 2-4 in.; the young leaves often with a purple blotch in the middle: involucre with less stiff bristles, about 1 1/2 in. long, 2 or sometimes 3 times as long as the nut, narrowed toward the apex. Japan. S.I.F. 1:20.

cc. Petioles shorter than 1/2in.

11. Rostrata, Ait

Fig. 1075. Shrub, 2-6 ft.: branchlets pubescent or glabrous, not bristly: leaves rounded or slightly cordate at the base, oval or obovate, densely serrate and sometimes slightly lobed, nearly glabrous at length, except sparingly pubescent on the veins beneath, 2 1/2-4 in. long: involucre densely beset with bristly hairs, beak long and narrow: nut ovoid, 1/2in. long. E. N. Amer., west to Minn, and Colo. G.F. 8:345 (adapted in Fig. 1075).

Corylus rostrata. (X 1/2)

Fig. 1075. Corylus rostrata. (X 1/2)

12. Californica, Rose

(C. rostrata variety californica, DC). Allied to C. rostrata. Shrub, to 20 ft.: leaves more villous beneath: involucre with a short beak, which is often flaring and sometimes torn. Calif, to Wash.

C. colchica, Alboff. Low shrub, to 3 ft.: leaves ovate or obovate, densely doubly serrate, sparingly pilose: involucre connate, with a short lacerated beak, pubescent. Caucasus. Winkl. 53. Not in cultivation - C. colurnoides, Schneid. (C. intermedia, Lodd., not Fingerh., C. ColurnaXC. Avellana). Similar to C. Colurna: small tree or large shrub, bark darker: involucre shorter, scarcely glandular. Garden origin. - C. Fargesii, Schneid. (C. mandshurica variety Far-gesii, Burkill). Tree to 45 ft.: leaves narrow-obovate to oblong: involucre soft-pubescent, sometimes only slightly so. W. China. - C. Jacquemontii, Decne. (C. Colurna variety lacera, DC). Allied to C. chinensis. Tree: leaves ovate, lobed toward the apex, less pubescent, 5-8 in. long: involucre pubescent, not constricted, lobes not or rarely forked, often dentate. Himalayas.

Alfred Rehder.