* Orohanclie minor - Plate 17 B.
* Salvia pratensis - Plate 17 D.
Closely allied to the Labiates is the Verbenaceous family, represented by the Common Vervain,* a weed plentiful by roadsides and in waste places in the southern parts of England. The blossoms bear no comparison with the handsome Verbenas of our gardens, which belong to the same genus. The plant is an erect-growing perennial, having stems one to two feet high, with long spreading wiry branches. The leaves are opposite, those on the lower part of the stem, where they are most numerous, obovate or oblong, stalked, and coarsely toothed or cut, the upper ones being few sessile and lance-shaped. The flowers are small, in long slender spikes terminating the stem and branches, crowded at first, but becoming distant below by the elongation of the spike; they consist of a five-toothed calyx, a tubular corolla with an unequal five-cleft spreading limb, four stamens included in the tube, and a two- or four-celled ovary bearing the style at top, and dividing into four one-seeded nuts.
Another of these irregular-flowered perigynous Monopetals is the Common Butterwort,† which belongs to the Lentibula-riaceous family. It is a little herb, found not uncommonly on wet rocks by mountain rills and in boggy places. It forms a rosulate tuft of spreading flat ovate or broadly oblong light green somewhat succulent leaves, which are involute at the margin and covered with soft glandular points which give them a clammy feel. The flower-stalks grow up among these to the height of four or five inches, and each terminate in a solitary bluish-purple flower. This consists of a two-lipped calyx, three-toothed in the upper lip and bifid in the lower; a two-lipped corolla spurred at the base, with a broad open mouth, a short broad two-lobed upper lip, and a longer threelobed lower lip; two stamens; and a one-celled ovary opening in two valves and containing many seeds. The common name of Butterwort appears to have arisen from the property which the leaves are said to possess, of coagulating milk.
* Verbena officinalis - Plate 17 C. † Pinguicula vulgaris - Plate 18 B.
The peculiar features of the Monochlamydeous group have been already pointed out. During the summer period many flowers having this peculiar structure will be met with, but the limited number of our figures will, as before, only afford a few selected illustrative examples.
We have here, first, the Bistort or Snakeweed,* a sample of the Polygonaceous family, which is distinguished among Mo-nochlamyds by having sheathing stipules. The Bistort is a perennial herb, found growing in moist pastures in various parts of Britain. It has a thick rootstock, from which spring up the patches of long-stalked ovate or cordate leaves, which are remarkable for their sudden contraction at the base into a narrow wing which borders the stalk. These are the leaves springing from the base of the plant, and are called the radical or root-leaves. The flower-stem grows quite upright, one to two feet high, with a few leaves on the lower part similar to the others, but smaller and with little or no stalk; at their base however is a kind of sheath surrounding the stem, so that the latter appears to grow through it. The sheath is formed of the united stipules - stipules being a pair of appendages assuming a variety of forms, produced on either side of the petiole or leaf-stalk at its base in certain families of plants. Here they coalesce and form a sheath or tube. The flowers form a close oblong spike at the top of the stem, and are of a pretty pink or light rose colour. The flowers have but one floral envelope, which is called the perianth, and this consists of five nearly equal segments, eight stamens considerably longer than the perianth, and three styles which are united at their base, surmounting a free ovary with a single ovule. The fruit is a small triangular seed-like nut, enclosed in the persistent perianth.
* Polygonum Blstorta - Plate 19 A.
The family of the Aristolochiaceous plants is another of these Monochlamydeous groups. It is represented by the Common Birthwort* a South European plant, naturalized among ruins and in stony rubbishy places in the east and south of England. This is a perennial, with a root creeping so extensively underground as to become a rather troublesome weed in situations which are congenial to it. The stems are erect, two to three feet high, several often springing up in a tuft, simple, striated, clothed with stalked, broadly heart-shaped leaves, reniform at the base. The flowers are yellow, collected in little groups in the axils of these leaves, clustered, or aggregated, as it is called; they are tubular, erect, or a little arching, globosely tumid at the base, and with a long slender slightly widening tube above, the upper side of which is prolonged into an oblique ovate concave emarginate limb. Within the globular portion at the base of perianth, are placed the anthers and stigmas: the latter being six-lobed, ray-like, terminating the short thick style, around which are fixed the six sessile anthers. The fresh plant when bruised has a strong disagreeable smell, resembling that of Elder. The tumid part of the corolla is covered inside with stiff hairs pointing downwards. When expanded, the flowers are frequently visited by a little insect, called Tipula pennicornis, which enters them, and is prevented by the hairs from making its egress until it has brushed off the pollen from the anthers on to the stigma: "the perianth then withers, the hairs become flaccid, and the insect makes its escape." This genus is one of very remarkable appearance, and some very striking exotic species are occasionally seen in hothouses. One of them, Aris-tolochia Gigas, has flowers of enormous size.
* Aristolochia Clematitis - Plate 19 B.
A very peculiar group referred to this Monochlamydeous series, is that of the Pinaceous or Coniferous plants, in which there is no perianth, and what is more remarkable, the ovules have no covering whatever, as they have in the case of other Orders of plants. The Scotch Fir* is a familiar example. This, as is well known, forms a large evergreen tree, which is renowned for its valuable timber. The branches are clothed with persistent leaves, which grow two together within little membranaceous or scarious sheaths, and in this manner they are thickly distributed over the branches; they are stiff, dark-green, awl-shaped or linear bodies, with a sharp point, and are straight and directed forwards or towards the point of the branch. The flowers grow in catkins, the two sexes separate. Those containing the male flowers consist of closely imbricated scales, on the inner face of which are two adnate anther-cells; the scales in this case are the connectives of the anthers, so that the catkins are in reality formed simply of closely imbricated anthers. In like manner the female catkins consist of closely packed scales, having two ovules on the inner face of each, these ovules having the open pore at their upper end, technically called the foramen, turned downwards. The male catkins fall away, but the female ones grow into the cone-like fruit, from which the family has acquired the name of Conifers, or Cone-bearers. This fruit, which is sessile, ovoid, conical, and recurved, consists, when mature, of hard woody scales, thickened upwards, and having a short thick point, which is often turned backward in the lower scales. Each scale encloses two seeds, which have an oblique membranaceous wing.