300 ARBORETUM AND FRUTICETUM. PART Ill. 
astringent. “ The spines of the common berberry are a curious state of leaf, 
in which the parenchyma is displaced, and the ribs have become indurated. 
They, as well as all the simple leaves of ordinary appearance, are articulated 
with the petiole, and are therefore compound leaves reduced to a single foliole ; 
whence the supposed genus Mahonia does not differ essentially from Bérberis 
in foliage any more than in fructification.” (Lindley, Introd. to N.S., p. 31.) 
The species are generally thorny, and most of them flower freely in spring, 
bearing fruit abundant!y in autumn. 
The irritability of the stamens of the genus Bérberis, and more par- 
ticularly of those of the common berberry, of B. canadénsis, B. sinénsis, 
and, perhaps, of all the species the flowers of which expand, is a very 
remarkable property, which was first discovered by Kolreuter ; probably 
from observing that the stamens were put in motion by the proboscis of 
insects extracting honey from the flowers. Sir James Edward Smith has 
given a copious account of this phenomenon in the Phil. Trans., vol. Ixxviil. 
p- 158., and the last, and most clear and concise, description of it will 
be found to be that by Dr. Lindley, under the article Bérberis, in the Penny 
Cyclopedia. The stamens, “ when the filament is touched on the inside with 
the point of a pin, or any other hard instrument, bend forward towards the 
pistil, touch the stigma with the anther, remain curved for a short time, and 
then partially recover their erect position. This is best seen in warm dry. 
weather. After heavy rain, the phenomenon can scarcely be observed, 
owing, in all probability, to the springs of the filaments having been already 
set in motion by the dashing of the rain upon them, or to the flowers having 
been forcibly struck against each other. The cause of this curious action, 
like that of all other vital phenomena, is unknown. ll that has been ascer- 
tained concerning it is this, that the irritability of the filament is affected 
differently by different noxious substances. It has been found by Messrs. 
Macaire and Marcet, that, if a berberry is poisoned with any corrosive agent, . 
such as arsenic or corrosive sublimate, the filaments become rigid and brittle, 
and lose their irritability; while, on the other hand, if the poisoning be effected 
by any narcotic, such as prussic acid, opium, or belladonna, the irritability is 
destroyed by the filaments becoming so relaxed and flaccid, that they can be 
easily bent in any direction. It is difficult to draw from this curious fact any 
other inference than this, viz. that in plants, as well as in animals, there is 
something analogous to a nervous principle, which is more highly developed 
in some plants, or in some organs, than in others.” (Pen. Cyc., iv. p. 260.) 
According to Sir J. E. Smith, the purpose of this remarkable function in the 
stamens of the berberry is evident. ‘‘ In the original position of the stamens 
the anthers are sheltered from rain by the concavity of the petals. Thus, 
probably, they remain till some insect comes to extract honey from the base 
of the flowers, and, thrusting itself between the filaments, unavoidably touches 
them in the most irritable part; and thus the impregnation of the germs is 
performed.” (Phil. Trans., \xxviii. p. 158.) All the species are easily propa- 
gated by seed, which most of them produce in abundance; those which do not 
are readily increased by the removal of their side suckers, or by layers. They 
will grow in any soil, though they mostly prefer one that is calcareous. 
Though the species of this genus are commonly treated as shrubs, and these 
shrubs, from their numerous side suckers, have, in general, a rough, inelegant 
appearance ; yet there are some of them which may be formed into the most 
beautiful and durable small trees that can be introduced into gardenesque 
scenery. The common berberry, when pruned up to a single stem to the 
height of 8 ft. or 10 ft., and all suckers from the root, and all side buds from 
the stem removed the moment they appear, will form a fine orbicular head 
with the extremities of the branches drooping ; and this pendulous appearance 
will increase with the age of the tree. Such a tree, covered, as it will be every 
year, with yellow blossoms in the beginning of summer, and with bright scarlet 
fruit in autumn, may rank in beauty and value with the low trees of the genera 
Cratz‘gus, Cotoneaster, and Amelanchier. ro 
