The genus Lobelia is well known from the pretty little blue-and-white flowering plants that are so common in pots for windows and balconies, and that continue flowering so freely all the summer. There are two or three species which are grown for this purpose, viz. _Lobelia Erinus_, _L. bicolor_, and _L. gracilis_, all annuals, which require to be raised on a hotbed by sowing in February, and which will then flower all the summer, with no other care than regular watering. All these flowers have the tube of the calyx united to the ovary, with a five-parted limb. The corolla is irregular and tubular, with the tube cleft on the upper side, and thickened at the base. The limb of the corolla is divided into two parts; one of which, called the upper lip, is cut into two narrow sharp-pointed segments, which stand erect; while the lower lip, which is much the longer, and hangs down, is cut into three rounded segments. There are five stamens, the anthers of which grow together, and at least two of them are bearded. The capsule is oval, two-celled, two-valved, and many-seeded, opening naturally at the top when ripe. These general characters will be found in all the numerous species of Lobelia, as the genus at present stands, as they all have the two horn-like segments of the upper lip, and the rounded lobes in the pendulous under lip; and many of the plants formerly called Lobelia which differ in these particulars have been placed in other genera. Thus Tupa, which contains several of the large scarlet-flowered species, has the segments of the limb of the corolla united at the tip; the filaments of the stamens cohering as well as the anthers, and the stigma protruding. Siphocampylos has the tube of the corolla ventricose in the middle, the segments of the upper lip long and curving over each other, and the lower lip very slightly lobed, with both the filaments and the anthers combined. In Dortmannia the filaments are free, and only the anthers combined; in Parastronthus (_L. unidentata_), there is scarcely any tube to the corolla, and in Isotoma, the corolla is salver-shaped. The beautiful little _Clintonia pulchella_ belongs to this order, and it differs from Lobelia in its corolla having scarcely any tube, and also, but more decidedly, in the very long tube of its calyx. This is so long and slender as to look like a part of the flower-stalk; as does the capsule, which, when ripe, is triangular, and is as long as the silique of a cabbage or wall-flower, to which it bears considerable resemblance. All the Lobeliaceæ have an acrid milky juice, which is poisonous. ORDER CX.—STYLIDEÆ.