Family: Scrophulariaceae
Common Name: Beard Tongue

This genus comprises over 250 species of perennials and shrubs, all native to North America, except for one species from north-eastern Asia. Many hybrids are also available, so there is a wide colour range, from white and yellow to pink, red, maroon, blue and purple. The tall varieties make excellent border plants, while the dwarf types look very colourful as bedding plants.

Species

P. azureus, zone 8, grows to 75 cm (30 in), with attractive, deep blue or purple flowers.

P. barbatus, zone 3, produces sprays of delightful, scarlet, tubular flowers, from mid-summer to early autumn. This perennial grows up to 2 m (6 ft) high. There are several cultivars available.

P. cobaea, zone 4, is a parent of some of the most popular hybrids. It has large, showy, purple or white flowers.

P. fruticosus, zone 4, with lavender-blue flowers, forms a dense clump and is also a parent of several popular varieties.

P. heterophyllus, zone 8, a shrub to 60 cm (24 in) high, has blue to purple flowers. It is an excellent border edging plant.

P. hirsutus, zone 3, is a perennial, to 1 m (3 ft), with purple or violet flowers, also producing several lovely cultivars.

P. triphyllus, zone 5, to 75 cm (30 in) high, has lavender to lilac-blue flowers and a staminode with thick, yellow hairs. Garden cultivars include 'Apple Blossom', 'Firebird', 'Garnet', 'Lady Hindley' and 'Sour Grapes'.

Cultivation

Plant in a loose, gravelly soil or a mixture of leaf mould, peat and loam. They require good drainage and an open, sunny situation. A weekly application of liquid fertilizer to the summer bedding species will produce good flowers. Species can be propagated from seed, in spring, under glass. All can be propagated from softwood or semi-ripe cuttings in summer, rooted with bottom heat. Divide established clumps in spring.

Climate

There are species suited to various climatic zones.