Commemorating Capt.William Clark (1770–1838), noted for the Lewis and Clark Expedition to the Rocky Mtn region in 1906.

Annual herbs. Leaves simple, linear to ovate, entire or with small teeth; stalks, if present, very short to as long as the blade. Flower clusters in a leafy spike with the flower buds erect or bent down. Flowers to 10 cm wide, funnel- or bell-shaped to elongated in pinks and purples, occasionally red or white and sometimes speckled or lined. Fruit a club-shaped to cylindrical, mostly grooved, capsule. Syn. Godetia Spach.

Available mostly as garden annuals with pink, red, lavender or white flowers, sometimes double, generally sold as flower colour seed mixes: C. concinna has 4 stamens and petals with 3 equal lobes, the central one spoon-shaped; C. pulchella has 8 stamens and petals with the lateral lobes narrower than the central one; C. unguiculata has 8 stamens and unlobed petals with long thin 'stalks'. Hybridisation between these species has occurred, sometimes producing double flowers.

C. amoena (Lehm.) Nels. &Macbr., Satin Flower, from California is occasionally available; it is an erect or sprawling plant to 1 m or more tall, generally grown as the smaller subsp. whitneyi (A. Gray) F.H. &M.E. Lewis which grows to about 40 cm tall and has large, showy lavender flowers with dark red centres.

33 species from W North America and S South America.

Seed.

Lewis & Lewis (1955).

Source: Spencer, R. (2002). Onagraceae. In: Spencer, R.. Horticultural Flora of South-eastern Australia. Volume 3. Flowering plants. Dicotyledons. Part 2. The identification of garden and cultivated plants. University of New South Wales Press.