This section is from the book "Handbook Of Hardy Trees, Shrubs, And Herbaceous Plants", by W. Botting Hemsley. Also available from Amazon: Handbook of hardy trees, shrubs, and herbaceous plants.
Annual or perennial herbs with alternate leaves and raee-mose flowers. Corolla irregular, slit down the upper or posterior side; lobes unequal, the 2 upper erect or recurved, the 3 lower straight or recurved. Stamens epipetalous; anthers connate, all or only two of them bearded. Capsule half-superior, and opening through the cells. There are 200 species of this genus, occurring in temperate and tropical regions, but chiefly in the latter. There are two native species, both very rare: L. Dortmanna, an aquatic with cylindrical bifistular leaves and racemose spikes of blue flowers; L. urens is a less showy plant, found on heaths near Axminster. This genus was named in honour of Lobel, a physician and botanist of the time of James I.
1. L. Einus (fig. 157). - This and its varieties are usually treated as annuals, though it is said to be perennial. There are many handsome varieties much in request for edging beds, borders, etc. Some of the varieties in cultivation are the offspring of L. bicolor and L. campanulata, or, perhaps, crosses between them. The flowers are some shade of blue or blue and white combined, or wholly white. They are all from the Cape of Good Hope.
Fig. 157. Lobelia Erinus. (1/2 nat. size.)
L. cardinalis, splendens and fulgens are Mexican perennial species of erect habit from 2 to 4 feet high, bearing terminal spikes of scarlet velvety flowers. The leaves are lanceolate and slightly toothed and often tinged with red. There are many hybrid varieties or simple variations of these magnificent plants in cultivation, but unfortunately they are somewhat tender. L. amaena is another North American species, having blue flowers in a one-sided spike. L. Tupa and L. ignescens are sometimes separated with some other species under the name of Tupa, on account of the persistent 5-lobed deflected corolla, the segments of which are joined at the tip. They are handsome herbaceous plants 3 or 4 feet high with bright scarlet flowers. The former is a Chilian and the latter a Mexican species; both are tender, and very rarely seen except in botanical gardens.