Other species worth growing are C. americana, heterophylla, mandshurica, and maxima, with its very fine variety atropurpurea, and other forms, among them the varieties of cobs and filbert nuts grown for their fruits.
The filbert is economically grown on the borders of plantations or orchards, or in open spots in woods.
As seen in commerce jujube fruits are about the size of a small filbert, having a reddish-brown, shining, somewhat wrinkled exterior, and a yellow or gingerbread coloured pulp enclosing a hard elongated stone.
The filbert, 2 among the numerous varieties of Corylus Avellana, is extensively cultivated, especially in Kent, for the sake of its nuts, which are readily distinguished from cob-nuts by their ample involucre and greater length.
Filbert nuts required for keeping must be gathered only when quite ripe; they may then be preserved in dry sand, or, after drying, by packing with a sprinkling of salt in sound casks or new FIG.
Their different forms include the Cosford, which are thin-shelled and oblong; the Downton, or large square nut, having a lancinated husk; the white or Wrotham Park filbert; and the red hazel or filbert, the kernel of which has a red pellicle.