Clarkia

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- 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. x = 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

Clarkia sect. Biortis, Clarkia sect. Clarkia, Clarkia sect. Eucharidium, Clarkia sect. Fibula, Clarkia sect. Godetia, Clarkia sect. Myxocarpa, Clarkia sect. Phaeostoma, Clarkia sect. Rhodanthos

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
2	Stamens 8; floral tube obconic to campanulate or funnelform, 1–10(–15) mm; petals lobed or not.	> 4
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
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
5	Inflorescence axis straight or erect; buds erect or pendent.	> 25
6	Petal claw broad with pair of lateral basal lobes; stamens subtended by ciliate scales [6d. sect. Myxocarpa].	> 7
6	Petals not clawed or claw not greater than 2 mm, without lateral lobes; stamens not subtended by scales.	> 14
7	Stigma not or rarely exserted beyond anthers; petals 6–12(–14) mm.	> 8
7	Stigma exserted beyond anthers (rarely so in C. virgata); petals (7–)12–20 mm.	> 10
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
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
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
15	Inner stamens shorter, inner anthers much smaller, paler.	> 18
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
18	Stigma not exserted beyond anthers; petals 5–12 mm.	> 19
18	Stigma exserted beyond anthers; petals 10–35 mm.	> 21
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
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
25	Buds pendent; corollas rotate or bowl-shaped; inner stamens shorter, inner anthers smaller, paler.	> 26
25	Buds erect; corollas bowl-shaped; stamens subequal, anthers of similar size and color.	> 33
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
27	Corollas rotate; petals clawed.	> 29
28	Seeds brown.	Clarkia bottae
28	Seeds gray.	Clarkia jolonensis
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
33	Sepals remaining connate along edges and reflexed together to 1 side.	> 34
33	Sepals reflexed individually or in pairs [6e. sect. Godetia].	> 38
34	Ovary 8-grooved.	> 35
34	Ovary 4-grooved [6c.1. sect. Rhodanthos subsect. Primigenia].	> 36
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
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
38	Stigma not exserted beyond anthers; petals 5–15 mm.	> 39
38	Stigma exserted beyond anthers; petals 10–30 mm.	> 41
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
41	Inflorescences dense; ovary at anthesis longer than adjacent internode.	> 42
41	Inflorescences open; ovary at anthesis shorter than adjacent internode.	> 43
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
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