From an Inaugural Essay.
This plant belongs to the natural order of Rosaceae, and, though considered to be of little importance medicinally, it presents many characteristics which cannot fail to be deeply interesting to the botanical student It is an upright, shrubby perennial, growing in rough pasture lands and thickets, throughout the eastern part of the United States from Maine to South Carolina, and it is universally known as High Blackberry.
Its flowers, consisting of five white rounded petals and numerous stamens, occur upon the irregularly branched stem in more or less elongated racemes, and produce, a, black multiple fruit, which ripens in August or September. The stem is longitudinally ridged, and armed with stoat downward curved prickles.
The leaves are slightly pubescent beneath, alternate and of a darkish green color; their general shape is ovate, with an acute apex and an unequally serrate margin. The prickles grow along the midrib and down the petiole, which is nearly the length of the leaf. All intermediate gradations are found between the single and the compound leaf of five leaflets., the five-divided being produced from the three-divided by lobes appearing upon the base, and becoming more deeply incised, so as to form a new set of leaflets.
The root varies from the one-eighth of an inch in diameter to the thickness of the little finger, and contains a tough, ligneous meditullium. The bark, in which the virtues wholly reside, is of a gray-brown color externally, and of a darker brown in the intermediate-layer, and is slightly wrinkled. A longitudinal section of the bark shows the fibrous or bast tissue, which makes it very tough and strong, although it can be torn in the direction of the fibre with comparative ease. The cross section presents the medullary rays and the wedge-shaped bundles of bast tissue. The epiphloeum consists of about six or seven layers of tabular cells, and the meditullium is quite porous from the numerous ducts. The bark is found in commerce-peeled from the inert woody portion.
Rubus villosus is also interesting from the fact that upon the leaves is found a minute fungus, to which Schweinitz gave the name Aecidium nitens, described in his "Synopsis Fungorum Carolina; Superioris" as growing upon the leaves, petioles and young branches of the entire genus. To the naked eye its appearance is that of an orange colored rust, but when magnified one hundred and fifty diameters it is found to consist of a large number of roundish granular bodies, which appear about the size of a pea, and are of a light orange or sometimes a deep crimson color. They are attached to the hairs, and are found more plentifully on the under surface of the leaves, these parts often becoming so thickly covered as to give to the plant an autumn tint or sunburnt appearance.
By cultivation Rubus villosus acquires the habits and appearance of an ornamental shrub, some of its numerous stamens becoming petals, and the flowers increasing in size; though by "trimming back" the new growing branches the amount and size of the fruit can be greatly increased.
Tannin is the principal constituent of the root bark. The leaves also contain this acid in a small amount, and the pleasant acidulous-taste of the fruit is due to the presence of citric and malic acids.