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 large genus of herbaceous or more rarely frutescent plants. Leaves opposite or whorled,- the uppermost often alternate. Flowers spicate or racemose, or solitary and axillary. This genus is remarkable for the personate open or closed corolla spurred at the base, with an erect upper lip and trilobate lower lip, the middle lobe smallest. Sometimes the corolla is regular, with 5 spurs and lobes, and 5 fertile stamens. Fertile stamens 4, included. Capsule opening by pores. The species are natives of Europe, North Africa, and West Asia, and about half a dozen occur in this country. Linarium is the Latin word for flax plant, and is applied to this genus in consequence of a similarity in the foliage of some species.
1. L. vulgaris. Toad-flax. - This is one of our handsomest native plants, producing its long bracteolate racemes of yellow and orange flowers from July to October. It is a glaucous erect perennial about 2 to 3 feet high, with linear or lanceolate glabrescent leaves. The Peloria, or variety with a regular corolla, is more frequently seen in this species than in any other. It is constant, and the one usually cultivated, but it is rare in the wild state.
2. L. Dalmatica. - A tall perennial from 3 to 4 feet high.
Leaves glaucous, sessile, ovate, acute. Flowers racemose, very near those of the preceding species, appearing in Summer. South of Europe.
L. Macroura is an allied glaucous perennial with yellow and orange flowers, remarkable for the very long spur. It is a native of the Crimea.
3. L. triornithophora. - A handsome though somewhat tender perennial from Portugal, but which will flower well if treated as an annual. It grows from 1 to 2 feet high, producing its flowers where it will succeed as a perennial throughout the Summer and Autumn. Leaves glabrous, ovate or lanceolate, usually in whorls of threes, with a stalked flower from the axil of each. Flowers large, purple, tinged with yellow on the lower lip.
4. L. alpina. - A dwarf tufted perennial with small linear or lanceolate glaucous leaves and terminal racemes of relatively small lilac-blue flowers with an orange-red lower lip. A native of the mountains of Europe, blooming in Summer.
5. L. purpurea. - A tall erect somewhat slender perennial from 2 to 4 feet high. Leaves glaucous, linear, lower whorled. Flowers in terminal bracteolate racemes, purple, rather small, the spur as long as the tube, produced all the Summer. South Europe.
6. L. Cymbalaria. Mother-of-thousands. - This is the creeping perennial species with slender stems, miniature Ivy-like glabrous leaves, and small lilac-blue flowers tinged with yellow on the lower lip, now become rather common on walls, old buildings, banks, etc. It is a European species, and frequent though probably not indigenous, in Britain. It produces its flowers in great profusion from May till September.
7. L. bipartita. - An annual species about a foot high with linear glaucous foliage and lilac-purple or pale violet flowers tinged with yellow on the lower lip. There is also a pure white and several other varieties. The specific name refers to the 2-lobed upper lip of the corolla. A native of North Africa.
L. tristis is another annual species with yellow flowers having a purple-brown mouth; L. spartea has large bright yellow flowers; and L. saxdtilis is a trailing plant with yellow flowers. There are many other very pretty species, both annual and perennial, but the foregoing selection includes nearly all that are desirable in the genus.
L. spuria and L. Elatine are the two annual species frequently found in cornfields. They are both small-flowered; the former erect with ovate or rounded leaves, the latter prostrate with hastate acute leaves.