Field and Woodland Plants

by William S. Furneaux

The whole plant is devoid of chlorophyll, and consequently has not the power of building up organic compounds after the manner of green plants; and, being parasitic on the roots of trees, it derives but little organic material from its host. To compensate for this the underground portion is so constructed that it can capture minute animals which exist in the soil, and has the power of digesting them and of absorbing the products of digestion.

The underground stems are quite white, and are thickly covered with broad, cordate, fleshy leaves that closely overlap one another. There appears to be nothing very remarkable in these underground leaves until one has been removed from the stem and closely examined; and then we find that what appears to be the apex of the leaf is really its middle; and that what seems to be, at first sight, the under surface, is really an extension of the upper side; for the leaf is bent backwards in such a manner as to bring its apex close to the stem, immediately below its base. This peculiar folding of the leaf results in the formation of an irregular cavity, and the tip of the leaf, brought close to its base, is curled upward, close to the stem, in such a way as to form a little canal, with several small openings by which the cavity may be reached. It will not be easy to make out this strange folding of the leaf by an examination of the exterior only, but a longitudinal section, made with a sharp knife or razor, will show it clearly.

Common Butterwort.

When minute animals enter the cavity of the leaf through the little openings above mentioned, they are seized by means of small filaments that protrude from the lining cells; and although no special digestive secretion has been discovered in the leaves, it appears certain that the creatures entrapped are really dissolved, for nothing remains of them after a time except the harder, indigestible portions. Also, there is every reason to believe that the products of digestion are absorbed, probably by the same filaments that are concerned in the capture of the microscopic prey.

Perhaps the most interesting of the carnivorous plants are those which exhibit distinct movements in connexion with the capture of their prey, and among these are the British Butterworts and Sundews, which grow in bogs and other wet places.

There are three British species of Butterwort (Pinguicula), similar in structure and habit, all growing in bogs and on wet rocks. They have each a rosette of entire, radical leaves, the lowest of which lie close against the soil or rock on which the plant grows; and violet or yellow flowers on leafless peduncles. The calyx has four or five teeth, arranged in two lips; and the corolla, which is also lipped, has a broad, open throat, and a spur.

The commonest species is the Common Butterwort (P. vulgaris), which is found in bogs and wet places, principally in the hilly, humid districts of the West of Britain and Ireland, flowering from May to July. Its leaves are succulent and clammy, of a pale green colour, and covered all over with little glistening spots. The flower stems are three or four inches high, each bearing a single violet flower. In this species the throat of the corolla is bell-shaped, and the spur is as long as the rest of the corolla.

A second species—the Alpine Butterwort (P. alpina)—with smaller, pale yellow flowers appearing in June and July, is found only in Scotland; while a third, known as the Pale Butterwort (P. lusitanica), also with pale yellow flowers, and a curved spur, occurs in South-West England as well as in the boggy districts of Ireland and the West of Scotland, flowering from June to October.

The carnivorous habits of all species are the same. The horizontal leaves lie flat on the wet soil, with their margins turned upward forming a kind of shallow trough; and the upper surface of each is dotted with many hundreds of minute glands which secrete a colourless, sticky fluid, thus giving to the leaf its glistening and clammy appearance.