Description of Clarkia:
Distribution: All but one species are endemic to western North America; the only exception is C. tenella, which occurs in Mediterranean-climate regions of Chile and Argentina. Several species of Clarkia are grown ornamentally, especially C. amoena, the “Godetia” of horticulture, and C. unguiculata, the common garden “Clarkia.” Both species and cultivars developed from them are used in annual border plantings or in hanging baskets. Clarkia pulchella is commonly cultivated, especially in Europe. Clarkia has been the subject of detailed systematic and evolutionary studies for more than half a century, and there are many reports of these studies in the literature (e.g., Holtsford & Ellstrand 1992; Eckhart et al. 2004, and references therein).
Habit: Herbs, annual, to 2 m tall, erect to prostrate. Stems slender or stout, simple to sparingly branched, glabrous and often glaucous to strigillose and/or villous, the basal epidermis usually exfoliating.
Leaves: Leaves cauline, simple, alternate, sessile or petiolate, blades linear to elliptic or ovate, margins entire or denticulate; stipules absent.
Flowers: Inflorescence a leafy spike or raceme, axis in bud erect or nodding, becoming straight as flowers open, bracts leaf-like, buds erect or not, sessile to pedicellate. Flowers hermaphroditic (often protandrous), actinomorphic or rarely slightly zygomorphic; floral tube present, deciduous (with sepals, petals, and stamens) after anthesis, obconic to cup-shaped or long and slender, usually with a ring of hairs within and nectary at base of tube; sepals 4, often colored, fused to the tip in bud, reflexed individually, in pairs, or as a unit to one side; petals 4, 5--60mm, lavender or pink to dark reddish purple, rarely blue (C. tenella), sometimes pale yellow or white, often spotted, flecked or streaked with red, purple, or white, oblanceolate to obovate or fan-shaped, frequently lobed or clawed; stamens 8 in 2 equal or unequal series, or 4 in 1 series, filaments filiform to clavate, sometimes subtended by hairy scales, anthers basifixed, often with short acute sterile tip, pollen cream, yellow, blue, or red, shed singly; ovary 4-locular, usually pubescent, stigma 4-lobed, the lobes commissural, receptive only on the inner surfaces, the surface dry with unicellular papillae, white or yellow to dark purple or red.
Fruit: Fruit usually a loculicidal elongate capsule 1--5 cm long, cylindric, spindle-shaped, or clavate, usually quadrangular (4- or 8-grooved and often deeply 8-ribbed), or sometimes terete, sometimes with sterile beak, often tardily dehiscent, or (in C. heterandra) indehiscent and nut-like.
Seeds: Seeds many or rarely (in C. heterandra) 1 or 2, 0.5--2 mm, usually angular, cubical or elongate, usually oblique, sometimes spindle-shaped, often with a crest of elongated cells, the surface scaly or minutely tuberculate, brown, gray, or mottled.
Chromosomes: Chromosome numbers: n = 5, 6, 7, 8, 9, 12, 14, 16, 17, 18, 26; x = 7 (floating translocations common).
Notes: FNA