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.
Herbs or shrubs, erect or prostrate in habit, with opposite and alternate or rarely whorled leaves. Flowers in terminal spikes or racemes, rarely solitary and axillary. Calyx 4- or 5-lobed. Corolla rotate or campanulate; limb unequally 4-lobed, spreading. Stamens 2, exserted. Capsule compressed or turgid, 2-valved. Seeds rather large. A very large genus, numbering upwards of 150 species, abounding in the temperate regions of the northern hemisphere and in Southern Australasia, Fifteen species are found in Britain. The etymology of the generic appellation is unexplained. The species are known by the English name of Speedwell.
1. V. spicata. - A perennial with erect flowering stems from 1 to 2 feet high, terminated by racemes of bright blue, rose or white flowers. Leaves pubescent, opposite, ovate, oblong, obtuse, sessile or petiolate, serrate or crenate. A native of South Britain, but rare and local. It produces its handsome spikes of flowers freely from June to August.
2. V. gentianoides. - A pale green perennial about 18 inches high, common in cottage gardens. Leaves opposite, linear, lanceolate, acute, crenate, three-nerved, with a cartilaginous margin, glabrescent. Flowers in terminal racemes, pale blue with darker lines, appearing in May or June. A native of Asia Minor.
3. V. saxdtilis. - A dwarf tufted evergreen species with spreading stems somewhat woody at the base. Leaves opposite, dark green, oblong-obovate, crenate. Flowers racemose, blue with darker lines and a white centre. A mountain plant, found in various parts of Europe, including the higher mountains of Scotland.
4. V. longifolia. - A tall variable plant with opposite or whorled ovate-lanceolate leaves, cordate or rounded at the base and doubly toothed towards the apex, and long dense terminal racemes of blue or pink flowers. V. incarnata and V. mari-tima are varieties of this species. It is a native of Central Europe.
We might extend this list considerably, but the species so nearly resemble each other that for general purposes the above will be found sufficient. V. Teucrium, V. Austriaca, V. ame-thystlna and V. Candida are occasionally cultivated. V. Cha-Tncedrys, Cat's-eyes, is one of the prettiest and commonest of native perennial species. It is a creeping hairy plant with ovate-cordate shortly petiolate deeply serrate leaves and axillary racemes of rather larger bright blue flowers. V, Beccabunga, Brooklime, and V. Anagallis are fleshy plants growing in wet places. The former has stalked oblong leaves and axillary racemes of blue or pink flowers; and the latter sessile stem-clasping leaves and pale blue or white flowers. In addition to the foregoing we must mention the New Zealand species, of which there are now many beautiful varieties in cultivation, but being rather tender they are more extensively grown for window and conservatory decoration in Autumn and Winter. Nevertheless they will flourish in the open air in the south-west near the sea with slight protection in very severe weather. These are evergreen shrubby species and varieties with axillary racemes of purple, blue, lilac, white, pink or crimson flowers. V. speciosa with glossy oblong entire coriaceous leaves, and V, salicifolia and V. macrocarpa with linear-lanceolate leaves, are the parents of the beautiful hybrid varieties, including V. Andersoni, V. versicolor, V. Lindleyana, V. kermesina, etc.
Ourisia coccinea is an exceedingly beautiful though rare creeping plant with ascending flowering stems about 6 inches high. Leaves all radical, broadly ovate, cordate, slightly lobed and toothed. Scapes bracteolate, bearing numerous drooping tubular scarlet flowers. A native of the Andes.
Besides the above enumerated plants of this order there is a large tribe of very handsome plants still almost unknown in cultivation, on account of the difficulties experienced in raising them artificially, due to the fact that they are mostly partially parasitical in the natural state on the roots of the plants they are associated with. This section includes amongst others the genera Gerardia, Pedicularis, Melampyrum, and Castilleja.