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.
A small genus of slender branching annuals with opposite or whorled leaves and clustered cymes of showy gaily-coloured flowers in the axils of the upper leaves. Calyx deeply 5-lobed. Corolla-tube saccate at the base on the upper side; limb bilabiate; upper lip bilobate, curved backwards; lower lip trilobate; middle lobe pouch-like, enclosing the 4 stamens. Capsule many-seeded, opening in valves. The species are all from North America, and chiefly Californian. The genus was dedicated to Zaccheus Collins, an American botanist of note.
1. C. blcolor (fig. 188). - This is the commonest species and one of the best for general purposes. It grows from 1 to 2 feet high with strongly-nerved lanceolate leaves, opposite or in threes. The flowers have the upper lip pale lilac 'or white, and the lower a deep lilac purple. There is also a variety with quite white flowers. C. grandiflora is a similar plant having rather larger flowers with a purplish lilac upper lip and a deep blue lower lip. C. multicolor has a broad white blotch spotted with crimson on the upper lip; C. heterophylla has the lower leaves trilobate, but otherwise very near G. bicolor, of which it may be a mere variety. G. verna is a distinct species in having the blue and white flowers on long stalks.
Fig. 188. Collinsia bicolor. (1/6 nat. size.)