50 
where Wilson saw trees of this Hazel up to one hundred and twenty- 
feet in height with trunks from two to five feet in diameter. The nuts 
are small and thick-shelled and are contained in husks less deeply lobed 
at the apex than those of C. Colvrna and arranged in compact clusters. 
The third arborescent species in the collection, C. tihetica, is a small 
tree from twenty to twenty-five feet high, or a large bush common in 
woods in central and western China. From the other species, with the 
exception of the related C. ferox of the Himalayas, it differs in the 
fruit which is covered with slender spines and arranged in compact, 
globose, spiny clusters which resemble a Chestnut burr. 
The other species in the collection are large or small shrubs. The 
two eastern American species, Corylus americana and C. rostrata, are 
common and widely distributed woodland plants often spreading over 
a considerable area. The former is a shrub from three to eight feet high 
with glandular bristly branches and an egg-shaped, thick-shelled nut en- 
closed in a husk nearly twice its length and irregularly toothed at the 
apex. C. rostrata is a smaller shrub rarely more than six feet high, with 
branches which are not furnished with bristles and an egg-shaped, 
thick-shelled nut about half an inch long and enclosed in a husk con- 
tracted into a long narrow beak extending an inch or more above the 
nut. C. californica is common in the coast region of the Pacific states 
from Washington to California where it sometimes grows to a height 
of twenty feet, and, while it differs in the leaves, resembles the east- 
ern C. rostrata in the beaked husk of the fruit which is, however, 
stouter than that of the eastern plant, and often open at the mouth. 
Only the two European species, C. Avellana and C. maxima, and 
possibly some of their hybrids, produce nuts of commercial value as 
human food. The hazel or hazel-nut is produced by Corylus Avellana. 
This is widely distributed in Europe and extends into northern Africa 
and western Asia, and sometimes grows to a height of twenty feet and 
usually forms large thickets by shoots produced from the root. The 
nut is thin-shelled, about three-quarters of an inch in length, and about 
as long as its husk which has divided, often toothed lobes. As the 
stems are very pliable and easily trained this shrub was used to form 
pleached or shaded walks more commonly found in European gardens 
a century ago than they are today. The large dark leaves cast a dense 
shade and no plant with a little training is better suited to protect a 
walk from the sun. There are several forms of this plant selected and 
cultivated for their nuts which vary in size and in the thickness of the 
shell; and a number of varieties differing in habit or in the color and 
size of the leaves from the type are sometimes found in collections of 
ornamental plants. In the Arboretum collection are now found only 
the var. pendula with distinctly drooping branches, the var. contorta 
with curled and twisted branches, and the var. quercifolia with lobed 
leaves. These plants are curiosities, without real value as garden 
plants. Other varieties not in the collection are var. aurea with yellow 
leaves, var. atropurpurea with purple leaves, and var. laciniata with 
deeply lobed leaves. From a Hazel of southwestern Asia which is some- 
times considered a variety of C. Avellana (var. pontica) and sometimes 
a species (C. pontica) the Cobnuts of commerce are at least partly ob- 
tained. This plant has not yet proved hardy in the Arboretum. A 
larger and more robust plant than C. Avellana is the Hazel of south- 
