Clarkia
Fl. Amer. Sept. 1: 256, 260 [. as Clarckia], plate 11. 1813
Herbs, annual, caulescent. Stems slender to stout, erect to prostrate or decumbent, unbranched to sparsely branched. Leaves cauline, alternate; stipules absent; sessile or petiolate, petiole usually shorter than blade; blade margins entire or denticulate. Inflorescences usually racemes or spikes, rarely panicles; buds erect or pendent. Flowers bisexual, usually actinomorphic, often protandrous; floral-tube deciduous (with sepals, petals, and stamens) after anthesis, usually with basal nectary and a ring of hairs inside; sepals 4, often pink to purplish red, usually connate to tip in bud, reflexed singly, in pairs, or all together to 1 side at anthesis; petals 4, usually lavender or pink to dark reddish purple, pale-yellow or white, [rarely blue (C. tenella)], often spotted, flecked or streaked with red, purple, or white; stamens 8, in 2 equal or unequal series, or 4 in 1 series, filaments filiform or expanded distally, sometimes subtended by hairy scales, anthers basifixed, often with short-acute sterile tip, pollen cream, yellow, blue-gray, lavender, or red, shed singly; ovary 4-locular, stigma 4-lobed, commissural, lobes receptive only on dry, unicellular-papillose inner surfaces. Fruit a capsule, elongate, straight or curved, cylindrical, fusiform, or subclavate, often 4-angled (shallowly to deeply 4-grooved or 8-grooved) or terete, loculicidal, often tardily dehiscent, sometimes with sterile beak, rarely short, indehiscent and nutlike (C. heterandra); sessile or pedicellate. Seeds usually numerous, rarely (C. heterandra) 1 or 2, usually angled, cubic, or elongate to spindle-shaped, often with crest of elongated cells, scaly or minutely tuberculate. = 7.
Distribution
w North America, w South America
Discussion
Species 42 (41 in the flora).
Molecular phylogenetic analysis places a strongly monophyletic Clarkia as sister to Gayophytum and Chylismiella (R. A. Levin et al. 2004). All but one species of Clarkia are endemic to western North America; the only exception is C. tenella (Cavanilles) H. Lewis & M. E. Lewis, which occurs in Mediterranean-climate regions of Argentina and Chile. Several species of Clarkia are grown ornamentally, especially C. amoena, the so-called 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 also 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 (H. Lewis and M. E. Lewis 1955; V. S. Ford and L. D. Gottlieb 2003; V. M. Eckhart et al 2004).
Selected References
None.
Lower Taxa
Key
| 1 | Capsules indehiscent, nutlike, 2–3 mm, 1 or 2 seeded [6h.7. sect. Phaeostoma subsect. Heterogaura]. | Clarkia heterandra |
| 1 | Capsules loculicidal, 10–70 mm, many-seeded. | > 2 |
| 2 | Stamens 4; floral tube slender, 13–35 mm; petals conspicuously 3-lobed [6a. sect. Eucharidium]. | > 3 |
| 3 | Petal length 2 times width, lobes ± equal or middle lobe wider. | Clarkia concinna |
| 3 | Petal length equal to width, middle lobe longer and much narrower. | Clarkia breweri |
| 2 | Stamens 8; floral tube obconic to campanulate or funnelform, 1–10(–15) mm; petals lobed or not. | > 4 |
| 4 | Inner anthers sterile; petals with 3 subequal lobes [6b. sect. Clarkia]. | Clarkia pulchella |
| 4 | Inner anthers fertile, anthers similar or inner much smaller, paler; petals not 3-lobed. | > 5 |
| 5 | Inflorescence axis recurved at tip in bud; buds pendent. | > 6 |
| 6 | Petal claw broad with pair of lateral basal lobes; stamens subtended by ciliate scales [6d. sect. Myxocarpa]. | > 7 |
| 7 | Stigma not or rarely exserted beyond anthers; petals 6–12(–14) mm. | > 8 |
| 8 | Petals not spotted; pollen yellow. | Clarkia stellata |
| 8 | Petals spotted or mottled or with darker flecks; pollen blue-gray. | > 9 |
| 9 | Inflorescence axis recurved only at tip in bud, straight 4+ nodes distal to open flowers. | Clarkia virgata |
| 9 | Inflorescence axis in bud recurved 1–3 nodes distal to open flowers. | Clarkia rhomboidea |
| 7 | Stigma exserted beyond anthers (rarely so in C. virgata); petals (7–)12–20 mm. | > 10 |
| 10 | Inflorescence axis recurved in bud, straight 1–3 nodes distal to open flowers; petal length 1.4–1.6 times width. | Clarkia mildrediae |
| 10 | Inflorescence axis recurved only at tip in bud, straight 4+ nodes distal to open flowers; petal length 1.5–3 times width. | > 11 |
| 11 | Flower buds fusiform, tip acute. | Clarkia borealis |
| 11 | Flower buds narrowly obovoid, tip obtuse. | > 12 |
| 12 | Petal length 1.5–2 times width. | Clarkia mosquinii |
| 12 | Petal length 1.9–3 times width. | > 13 |
| 13 | Leaf blades elliptic to ovate. | Clarkia virgata |
| 13 | Leaf blades linear to lanceolate. | Clarkia australis |
| 6 | Petals not clawed or claw not greater than 2 mm, without lateral lobes; stamens not subtended by scales. | > 14 |
| 14 | Petals shallowly to deeply 2-lobed [6h.1. sect. Phaeostoma subsect. Lautiflorae]. | Clarkia biloba |
| 14 | Petals not 2-lobed, sometimes emarginate. | > 15 |
| 15 | Stamens subequal, anthers of similar size and color. | > 16 |
| 16 | Ovary 4-grooved; capsules usually wider distally [6c.3. sect. Rhodanthos subsect. Jugales]. | Clarkia gracilis |
| 16 | Ovary conspicuously 8-grooved; capsules not wider distally [6c.2. sect. Rhodanthos subsect. Flexicaules]. | > 17 |
| 17 | Stigma not exserted beyond anthers; pedicel in fruit 0–3 mm. | Clarkia lassenensis |
| 17 | Stigma exserted beyond anthers; pedicel in fruit 5–15 mm. | Clarkia arcuata |
| 15 | Inner stamens shorter, inner anthers much smaller, paler. | > 18 |
| 18 | Stigma not exserted beyond anthers; petals 5–12 mm. | > 19 |
| 19 | Petals white to pale cream, not flecked, fading pink [6h.3. sect. Phaeostoma subsect. Micranthae]. | Clarkia epilobioides |
| 19 | Petals pale to dark pink, usually darker flecked. | > 20 |
| 20 | Petals pink, usually darker flecked [6h.1. sect. Phaeostoma subsect. Lautiflorae]. | Clarkia modesta |
| 20 | Petals pale pink, shading nearly white near base, purple- flecked [6h.2. sect. Phaeostoma subsect. Prognatae]. | Clarkia similis |
| 18 | Stigma exserted beyond anthers; petals 10–35 mm. | > 21 |
| 21 | Corollas rotate; petals oblanceolate [6h.1. sect. Phaeostoma subsect. Lautiflorae]. | Clarkia lingulata |
| 21 | Corollas bowl-shaped; petals fan-shaped. | > 22 |
| 22 | Ovary 8-grooved [6h.1. sect. Phaeostoma subsect. Lautiflorae] . | Clarkia dudleyana |
| 22 | Ovary 4-grooved [6h.5. sect. Phaeostoma subsect. Sympherica]. | > 23 |
| 23 | Width of outer filaments about 2 times inner; floral tube 2–7 mm ring of hairs in floral tube below rim. | Clarkia cylindrica |
| 23 | Width of all filaments about equal or inner slightly thinner; floral tube 1.5–4 mm ring of hairs in floral tube at rim. | > 24 |
| 24 | Capsule beak 0–3 mm . | Clarkia lewisii |
| 24 | Capsule beak 7–15 mm. | Clarkia rostrata |
| 5 | Inflorescence axis straight or erect; buds erect or pendent. | > 25 |
| 25 | Buds pendent; corollas rotate or bowl-shaped; inner stamens shorter, inner anthers smaller, paler. | > 26 |
| 26 | Petals 2-lobed, with a slender central tooth [6g. sect. Fibula]. | Clarkia xantiana |
| 26 | Petals not lobed. | > 27 |
| 27 | Corollas bowl-shaped; petals not clawed [6g. sect. Fibula]. | > 28 |
| 28 | Seeds brown. | Clarkia bottae |
| 28 | Seeds gray. | Clarkia jolonensis |
| 27 | Corollas rotate; petals clawed. | > 29 |
| 29 | Petal claw shorter than blade [6h.4. sect. Phaeostoma subsect. Connubium]. | Clarkia delicata |
| 29 | Petal claw equal to or longer than blade [6h.6. sect. Phaeostoma subsect. Phaeostoma]. | > 30 |
| 30 | Sepals and ovary puberulent, mixed with longer, straight spreading hairs to 3 mm. | Clarkia unguiculata |
| 30 | Sepals and ovary sparsely to densely puberulent, without longer, straight spreading hairs. | > 31 |
| 31 | Leaf blades not glaucous, bright green. | Clarkia exilis |
| 31 | Leaf blades glaucous, gray-green or reddish green. | > 32 |
| 32 | Sepals usually dark red-purple; stigma exserted beyond anthers. | Clarkia springvillensis |
| 32 | Sepals green, red-tinged or not; stigma exserted or not beyond anthers. | Clarkia tembloriensis |
| 25 | Buds erect; corollas bowl-shaped; stamens subequal, anthers of similar size and color. | > 33 |
| 33 | Sepals remaining connate along edges and reflexed together to 1 side. | > 34 |
| 34 | Ovary 8-grooved. | > 35 |
| 35 | Petals 30–60 mm; ovary fusiform [6c.1. sect. Rhodanthos subsect. Primigenia]. | Clarkia amoena |
| 35 | Petals 5–15 mm; ovary cylindrical [6f. sect. Biortis]. | Clarkia affinis |
| 34 | Ovary 4-grooved [6c.1. sect. Rhodanthos subsect. Primigenia]. | > 36 |
| 36 | Petals with distinct red spot or mark near middle. | Clarkia amoena |
| 36 | Petals red or reddish purple at base. | > 37 |
| 37 | Petals 10–30 mm; stigma exserted beyond anthers. | Clarkia rubicunda |
| 37 | Petals 5–13 mm; stigma not exserted beyond anthers. | Clarkia franciscana |
| 33 | Sepals reflexed individually or in pairs [6e. sect. Godetia]. | > 38 |
| 38 | Stigma not exserted beyond anthers; petals 5–15 mm. | > 39 |
| 39 | Stems erect; leaf blades usually linear to lanceolate, apex acute. | Clarkia purpurea |
| 39 | Stems prostrate to decumbent; leaf blades elliptic to oblanceolate, apex usually obtuse. | > 40 |
| 40 | Petals 5–11 mm, without spot. | Clarkia davyi |
| 40 | Petals 10–15 mm, with red spot above base. | Clarkia prostrata |
| 38 | Stigma exserted beyond anthers; petals 10–30 mm. | > 41 |
| 41 | Inflorescences dense; ovary at anthesis longer than adjacent internode. | > 42 |
| 42 | Floral tube conspicuously veined; petals with large, wedge-shaped purplish red spot near apex. | Clarkia imbricata |
| 42 | Floral tube not conspicuously veined; petals with red spot near or proximal to middle. | Clarkia speciosa |
| 41 | Inflorescences open; ovary at anthesis shorter than adjacent internode. | > 43 |
| 43 | Buds mucronate, sepal tips distinct in bud. | Clarkia williamsonii |
| 43 | Buds not mucronate, sepal tips connate to tip. | > 44 |
| 44 | Petals without red or red-purple spot. | Clarkia speciosa |
| 44 | Petals with conspicuous red or purple spot. | > 45 |
| 45 | Petal spot at or proximal to middle. | Clarkia speciosa |
| 45 | Petal spot distal to middle. | Clarkia purpurea |