Another of the same series, is the Reed-mace or Cat's-tail, often called Bulrush,* a type of the Typhaceous family, in which the flowers, which are collected into dense spikes, have no perianth, but are monoecious, that is, separate, though growing on the same individuals. This plant is an aquatic perennial herb, with a thickish creeping rootstock, and erect reed-like stems, four to six feet high, having very long erect linear leaves, sheathing at the base, but flat and of a glaucous-green upwards. The flower-spike is terminal on the stem, and is often a foot long or more. When in flower, the upper portion, which is continuous with the lower, not separated by a short interval as appears in the figure, and consists of male flowers, is rather the thickest, and is yellow from the numerous, closely packed, linear anthers; the minute ovaries of the lower part, which is of a deep brown, a colour given to it by the protruded stigmas, are also closely packed, and enveloped in tufts of soft hairs. When in fruit, the upper part becomes bare, or appears smaller from the shrinking of the dead stamens, and the lower part much thicker by the enlargement of the nuts, which are still enveloped in the thick, dark-coloured felt, formed by the hairs and stigmas, and at length become stalked. The fruit is a small seed-like nut, which continues small, and enveloped in the downy hairs. The plants are very stately objects in damp situations - these Typhas "marshalled in battalions, like grenadiers with hairy caps of the olden day." There is but little difference between the two species found in this country, the chief points of dissimilarity being the slightly smaller size, the narrower leaves, and the slightly interrupted flower-spike.

* Typha lalifolia - Plate 21 B.

The Ivy-leaved Duckweed* is a curious little plant, coming in the same category as the last. The group of Duckweeds consists of singular aquatic plants, resembling little green scales floating on the surface of stagnant waters, and forming part of the Pistiaceous, or, as Mr. Bentham calls it, Lemna-ceous family. They are but rarely met with in flower, and the flowers are so small and simple, that even when present they are not readily detected. The Ivy-leaved species represented in our plate, "has, it will be seen, no distinct stem or leaves, but consists of small, leaf-like fronds, of a lance-shaped figure, minutely toothed at one end, and tapering to a stalklike base at the other. Usually two young fronds grow from opposite sides of the older one near its base, each one producing eventually a single root from beneath. In this way growth goes on, the fronds becoming detached, and themselves producing others from their sides. The roots, which strike down perpendicularly, are in all the species capped by a small calyptra, or sheath. They increase "not only by seeds, but more abundantly by buds concealed in the lateral clefts of the parent frond, which growing out on two opposite sides into new plants, and these again producing offspring in the same way, while still attached to their parents, present a most curious appearance." The minute flowers grow from a fissure in the edge of the frond, two together, the inflorescence consisting of a membranaceous bract or spathe enclosing two stamens, and a single one-celled ovary, both without trace of a perianth. Dr. Lindley describes this structure as follows: - the flowers are two in number, one male and the other female, lying concealed in a slit of the frond; they have neither calyx nor corolla, but are enclosed in a delicate, membranous bag. The other species have rounder and thicker fronds than our example, and branch out in a similar manner, but less regularly, or at least, from their crowded condition, more confusedly than that we have described. Usually there is but one root to each frond, but in the Greater Duckweed, Lemna (or Spirodela) po-lyrhha, a cluster of roots is produced under each.

* Lemna frisulca - Plato 21 E.

Still bearing imperfect, but in some cases hermaphrodite flowers, there is the family of the Naiadaceous plants, represented by the Broad Pond weed.* This is a perennial herb, with long submerged branching stems, furnished with alternate stalked leaves, of which the uppermost float on the surface of the water, and the lower are sometimes reduced to a mere stalk. These floating leaves are largish, of an ovate form, thick in texture, marked by longitudinal nerves, and having a sheathing scarious stipule in the axil of their stalks. The flowers are small, sessile, arranged in spikes, which terminate the axillary flower-stalks, and which stand up above the water; they consist of four small green scales, representing a perianth; four stamens, with sessile anthers opposite these scales; and four distinct carpels, each with a sessile stigma. It is a common plant in stagnant waters and slow streams. Some botanists refer this genus to the Juncaginaceous family.

Passing on to the series in which the flowers are furnished with a calyx and corolla, and both stamens and pistil, the ovary being free, we come to one or two groups in which the perianth nevertheless bears a very inconspicuous character. The first of these is represented by the Sweet Flag,† by some referred to the Araceous family, but more fittingly associated with that of the Orontiaceous plants. It is a reed-like plant with thick, shortly creeping rootstocks, and everywhere highly aromatic. The leaves are linear, sword-shaped, erect, two to three feet long. The flowering stem is also erect, simple, and very much resembling the leaves, its long linear, leaf-like spathe forming a flattened continuation of the stalk portion which supports the dense cylindrical green spike or spadix of flowers. The spike, which pushes out sideways, while the spathe grows erect, appears, indeed, as if it grew out of the side of a leaf; it is sessile, stoutish, two to three inches long, consisting of numerous hermaphrodite flowers closely packed, the flowers consisting of six short green scales, six stamens, and a two- or three-celled ovary. The aromatic herbage of this plant is sometimes used for flavouring beer and spirits, and in Norfolk, where it abounds, it is said to be strewed on the floors of the churches on festival days.