51 
ern Europe, C. maxima. This is a vigorous and hardy shrub with large 
leaves and a large oblong nut enclosed in a husk produced in a long 
narrow tube and nearly twice the length of the nut. It is this plant 
and its selected forms which produce the filberts of commerce, which 
are also probably obtained from hybrids of C. maxima and C. Avellana. 
A variety of C. maxima with very dark red-purple leaves is the largest 
and most vigorous of all purple-leaved shrubs. Of the shrubby Asiatic 
species in the collection C. heterophylla of Japan or eastern China is 
an oriental representative of C. Avellana, from which it may be distin- 
guished by the more regular dentation of the husk. The still little 
known var. sutchuenensis of this species from western China is grow- 
ing well in the Arboretum but has not yet produced fruit. C. Siehold- 
iana with the long beak to the fruit is related to the American C. ros- 
trata; it is a shrub which often grows to the height of fifteen feet and 
differs from the Korean and Mandshurian Hazel (var. mandshurica), 
often considered a species (C, mandshurica) in its much shorter tube 
of the husk. In the collection there is also a plant for which the Ar- 
boretum is indebted to Dr. R. T. Morris of New York and which is be- 
lieved to be a hybrid of C. americana and C. Avellana var. pontica. 
This hybrid, which was raised artificially by Dr. Morris, has not flow- 
ered in the Arboretum. The Arboretum still needs the following spe- 
cies: Corylus ferox and C. Jacquemontii of the Himalayas, C. hallai- 
sensis of southern Korea, and C. colchica of the Caucasus. It lacks, 
too, many varieties of C. Avellana and several of its supposed hybrids. 
Coluteas, or Bladder Sennas as they are popularly called, are shrubs 
of the Pea Family with deciduous pinnate leaves, small leaflets, long- 
stemmed racemes of yellow or dark orange-red flowers and large inflated 
reddish brown pods. The flowers open in succession from June until 
August, and the pods from the early flowers are fully grown when the 
late flowers are still opening, the flowers and fruits together making 
an attractive appearance, as can be seen in the Shrub Collection where 
three species are now covered with flowers and fruits. They are C. 
arborescens, a native of the Mediterranean region and southeastern 
Europe, with dull green leaves and bright yellow flowers; C. cilicica, 
a native of Asia Minor, with blue-green leaves and yellow flowers; and 
C. orientalis, a native of southeastern Europe and Asia Minor, with 
glaucous leaves and reddish brown flowers. There is a dwarf compact 
form of C. arborescens (var. bullata) in the Arboretum, but the other 
species and a supposed hybrid (C. media) between C. arborescens and 
C. orientalis have not succeeded here. 
Shrub. This is the old and usually accepted popular name for the 
plants of the North American genus Calycanthus, famous for the fra- 
grance of the flowers of at least one of its species. One of the three or 
four species, C. occidentalis, a native of California, although it has 
often been planted in the Arboretum has not proved hardy here. Two of 
the eastern species are now covered with flowers in the Shrub Collection 
where, helped by the mild winter, they are in unusually good condition. 
The best known species, at least in gardens, Calycanthus jioridus, to 
which the name Shrub properly belongs on account of the delightful fra- 
grance of the red-brown flowers, is better worth a place in the garden 
than the other species of the genus, although in Massachusetts the 
