The genus Erodium consists principally of European plants, three of which are natives of England. The commonest of these (_Erodium cicutarium_) is called in many parts of England the Wild Geranium; and nearly allied to it, but less common, is _E. moschatum_. The principal points in which this genus differs from Pelargonium are, that the filaments of the stamens are very little united at the base; that there are always five filaments which bear anthers, and five that are sterile, and that the latter have each a gland at the base. The calyx is also without the spur, and the seed-pod is thought to resemble a heron’s head more than that of a stork. When it bursts, also, the styles, which are hairy inside like those of the Pelargonium, do not curl up in the same manner as in that genus, but spirally. The genus Geranium differs from Erodium principally in having the stamens all perfect; but the alternate ones are longer than the others, and have a gland at the base of each. The seed-pod is said to resemble the head of a crane, and when it bursts, the styles, which are smooth inside, curl up round and round like the coil of a rope. The seeds of many of the kinds are beautifully netted. Many of the species are British weeds, and among the commonest of these may be mentioned Herb Robert (_Geranium Robertianum_), and the Meadow Crane’s-bill (_G. pratense_). Dr. Lindley, in his Ladies’ Botany, mentions a curious and beautiful experiment which may be performed by pressing the petals of a Geranium between two pieces of glass which have been previously wetted. He says, that by pressing the two glasses firmly together, all the air may be squeezed out of the petal, and it will become transparent. “You may then,” he adds, “with a pretty good magnifying power, observe all the air-vessels of the veins distinctly, looking like fine threads of silver-wire twisted up like a spiral spring. It is on account of this appearance that the air-vessels are called, technically, spiral vessels.” The experiment appeared to me so easy, and at the same time so interesting, that I tried it, but unfortunately without success; probably owing to the want of power in my microscope. ORDER LI.—LIMNANTHEÆ. This little order contains only one plant, _Limnanthes Douglassi_, a pretty Californian annual, with yellow and white flowers. It resembles Geraniaceæ in its botanical construction, but it does not discharge its seeds with elasticity. ORDER LI.—TROPÆOLACEÆ.—THE NASTURTIUM TRIBE.