Greek pente — five, stemon — stamen, referring to the fifth sterile stamen.
Perennial herbs or subshrubs. Leaves opposite, occasionally in whorls of 3 or the upper ones stalkless and alternate. Flower clusters terminal, sometimes branched or solitary. Flowers white to red, purple, blue or yellow. Calyx 5-parted. Corolla tubular and more or less 2-lipped, the upper lip 2-lobed. Stamens 4, the fifth a sterile staminode that is sometimes bearded. Fruit a capsule containing numerous seeds. [Pentstemon Mitch.]
Grown for the attractively coloured flowers that appear rather late in the season; they are occasionally treated as annuals.
Seed, division, or occasionally by semi-hardwood cuttings.
Sterile stamen bent back on the corolla.
About 260 species from NE Asia (1 species), N and C America.
Keck (1932), Straw (1966), Lord (1994), Way & James (1998), Nold (1999). Cultivars: Lindgren & Davenport (1992), also lists published in the Bulletin of the American Penstemon Society.
Source: (2002). Scrophulariaceae. In: . Horticultural Flora of South-eastern Australia. Volume 4. Flowering plants. Dicotyledons. Part 3. The identification of garden and cultivated plants. University of New South Wales Press.
Many of the garden colour cultivars are the hybrid, P. cobaea × P. hartwegii, sometimes listed under P. ×gloxinioides hort.
Records of cultivars are improving but many have unknown origins.Most of the blue-flowered cultivars are derived from P. heterophyllus and these would include P. 'Blue Spring'.
Available but without description are: P. 'Barbara Barker', P. 'Crimson Robe', P. 'Stapleford Gem', P. 'Swan Lake', P. 'Thorn' and P. 'White Bedder'.
Flowers pale blue-violet, suffused with white and with a white throat.
Plant to about 1m tall. Flowers large, bell-shaped, purplish with no white in the throat, long-flowering. [P. 'Garnet']
Large, delicate pink and white blooms, possibly incorrectly known as P. 'Beech Park'.
Flowers small and pink.
Originated in at least 1949 from the Slieve Donnard Nursery, Northern Ireland.
Flowers dark red with a trace of white in the throat.
It is uncertain whether this plant is synonymous with P. 'Schönholzeri' or not.
To about 70 cm tall, with flowers deep blue-purple.
A mat-forming cultivar of P. rupicola.
Large, deep red flowers with pure white throats.
P. rupicola cross raised by Mr Elliott at the Six Hills Nursery, Stevenage, Hertfordshire, UK.