Clarkia in Flora of North America @ efloras.org

6. CLARKIA Pursh, Fl. Amer. Sept. 1: 256, 260 [as Clarckia], plate 11. 1813.

[For Captain William Clark, 1770–1838, of the Lewis and Clark Expedition]

Harlan Lewis†
Peter C. Hoch

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.

Species 42 (41 in the flora): w North America, w South America.

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 Gottlieb, L. D. and V. S. Ford. 1996. Phylogenetic relationships among the sections of Clarkia (Onagraceae) inferred from the nucleotide sequences of PgiC. Syst. Bot. 21: 45–62. Lewis, H. and M. E. Lewis. 1955. The genus Clarkia. Univ. Calif. Publ. Bot. 20: 241–392. Sytsma, K. J., J. F. Smith, and L. D. Gottlieb. 1990. Phylogenetics in Clarkia (Onagraceae): Restriction site mapping of chloroplast DNA. Syst. Bot. 15: 280–295.

1 Capsules indehiscent, nutlike, 2–3 mm, 1 or 2 seeded [6h.7. sect. Phaeostoma subsect. Heterogaura] 41 Clarkia heterandra

+ Capsules loculicidal, 10–70 mm, many-seeded. (2)

2 (1) Stamens 4; floral tube slender, 13–35 mm; petals conspicuously 3-lobed [6a. sect. Eucharidium]. (3)

+ Stamens 8; floral tube obconic to campanulate or funnelform, 1–10(–15) mm; petals lobed or not. (4)

3 (2) Petal length 2 times width, lobes ± equal or middle lobe wider 1 Clarkia concinna

+ Petal length equal to width, middle lobe longer and much narrower 2 Clarkia breweri

4 (2) Inner anthers sterile; petals with 3 subequal lobes [6b. sect. Clarkia] 3 Clarkia pulchella

+ Inner anthers fertile, anthers similar or inner much smaller, paler; petals not 3-lobed. (5)

5 (4) Inflorescence axis recurved at tip in bud; buds pendent. (6)

+ Inflorescence axis straight or erect; buds erect or pendent. (25)

6 (5) Petal claw broad with pair of lateral basal lobes; stamens subtended by ciliate scales [6d. sect. Myxocarpa]. (7)

+ Petals not clawed or claw not greater than 2 mm, without lateral lobes; stamens not subtended by scales. (14)

7 (6) Stigma not or rarely exserted beyond anthers; petals 6–12(–14) mm. (8)

+ Stigma exserted beyond anthers (rarely so in C. virgata); petals (7–)12–20 mm. (10)

8 (7) Petals not spotted; pollen yellow 12 Clarkia stellata

+ Petals spotted or mottled or with darker flecks; pollen blue-gray. (9)

9 (8) Inflorescence axis recurved only at tip in bud, straight 4+ nodes distal to open flowers 14 Clarkia virgata (in part)

+ Inflorescence axis in bud recurved 1–3 nodes distal to open flowers 16 Clarkia rhomboidea

10 (7) Inflorescence axis recurved in bud, straight 1–3 nodes distal to open flowers; petal length 1.4–1.6 times width 11 Clarkia mildrediae

+ Inflorescence axis recurved only at tip in bud, straight 4+ nodes distal to open flowers; petal length 1.5–3 times width. (11)

11 (10) Flower buds fusiform, tip acute 10 Clarkia borealis

+ Flower buds narrowly obovoid, tip obtuse. (12)

12 (11) Petal length 1.5–2 times width 13 Clarkia mosquinii

+ Petal length 1.9–3 times width. (13)

13 (12) Leaf blades elliptic to ovate 14 Clarkia virgata (in part)

+ Leaf blades linear to lanceolate 15 Clarkia australis

14 (6) Petals shallowly to deeply 2-lobed [6h.1. sect. Phaeostoma subsect. Lautiflorae] 27 Clarkia biloba

+ Petals not 2-lobed, sometimes emarginate. (15)

15 (14) Stamens subequal, anthers of similar size and color. (16)

+ Inner stamens shorter, inner anthers much smaller, paler. (18)

16 (15) Ovary 4-grooved; capsules usually wider distally [6c.3. sect. Rhodanthos subsect. Jugales] 9 Clarkia gracilis

+ Ovary conspicuously 8-grooved; capsules not wider distally [6c.2. sect. Rhodanthos subsect. Flexicaules]. (17)

17 (16) Stigma not exserted beyond anthers; pedicel in fruit 0–3 mm 7 Clarkia lassenensis

+ Stigma exserted beyond anthers; pedicel in fruit 5–15 mm 8 Clarkia arcuata

18 (15) Stigma not exserted beyond anthers; petals 5–12 mm. (19)

+ Stigma exserted beyond anthers; petals 10–35 mm. (21)

19 (18) Petals white to pale cream, not flecked, fading pink [6h.3. sect. Phaeostoma subsect. Micranthae] 32 Clarkia epilobioides

+ Petals pale to dark pink, usually darker flecked. (20)

20 (19) Petals pink, usually darker flecked [6h.1. sect. Phaeostoma subsect. Lautiflorae] 30 Clarkia modesta

+ Petals pale pink, shading nearly white near base, purple- flecked [6h.2. sect. Phaeostoma subsect. Prognatae] 31 Clarkia similis

21 (18) Corollas rotate; petals oblanceolate [6h.1. sect. Phaeostoma subsect. Lautiflorae] 28 Clarkia lingulata

+ Corollas bowl-shaped; petals fan-shaped. (22)

22 (22) Ovary 8-grooved [6h.1. sect. Phaeostoma subsect. Lautiflorae] 29 Clarkia dudleyana

+ Ovary 4-grooved [6h.5. sect. Phaeostoma subsect. Sympherica]. (23)

23 (22) Width of outer filaments about 2 times inner; floral tube 2–7 mm ring of hairs in floral tube below rim 35 Clarkia cylindrica

+ 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 (24) Capsule beak 0–3 mm 34 Clarkia lewisii

+ Capsule beak 7–15 mm 36 Clarkia rostrata

25 (5) Buds pendent; corollas rotate or bowl-shaped; inner stamens shorter, inner anthers smaller, paler. (26)

+ Buds erect; corollas bowl-shaped; stamens subequal, anthers of similar size and color. (33)

26 (25) Petals 2-lobed, with a slender central tooth [6g. sect. Fibula] 26 Clarkia xantiana

+ Petals not lobed. (27)

27 (26) Corollas bowl-shaped; petals not clawed [6g. sect. Fibula]. (28)

+ Corollas rotate; petals clawed. (29)

28 (27) Seeds brown 24 Clarkia bottae

+ Seeds gray 25 Clarkia jolonensis

29 (27) Petal claw shorter than blade [6h.4. sect. Phaeostoma subsect. Connubium] 33 Clarkia delicata

+ Petal claw equal to or longer than blade [6h.6. sect. Phaeostoma subsect. Phaeostoma]. (30)

30 (29) Sepals and ovary puberulent, mixed with longer, straight spreading hairs to 3 mm 37 Clarkia unguiculata

+ Sepals and ovary sparsely to densely puberulent, without longer, straight spreading hairs. (31)

31 (30) Leaf blades not glaucous, bright green 39 Clarkia exilis

+ Leaf blades glaucous, gray-green or reddish green. (32)

32 (31) Sepals usually dark red-purple; stigma exserted beyond anthers 38 Clarkia springvillensis

+ Sepals green, red-tinged or not; stigma exserted or not beyond anthers 40 Clarkia tembloriensis

33 (25) Sepals remaining connate along edges and reflexed together to 1 side. (34)

+ Sepals reflexed individually or in pairs [6e. sect. Godetia]. (38)

34 (33) Ovary 8-grooved. (35)

+ Ovary 4-grooved [6c.1. sect. Rhodanthos subsect. Primigenia]. (36)

35 (34) Petals 30–60 mm; ovary fusiform [6c.1. sect. Rhodanthos subsect. Primigenia] 4 Clarkia amoena (in part)

+ Petals 5–15 mm; ovary cylindrical [6f. sect. Biortis] 23 Clarkia affinis

36 (34) Petals with distinct red spot or mark near middle 4 Clarkia amoena (in part)

+ Petals red or reddish purple at base. (37)

37 (36) Petals 10–30 mm; stigma exserted beyond anthers 5 Clarkia rubicunda

+ Petals 5–13 mm; stigma not exserted beyond anthers 6 Clarkia franciscana

38 (33) Stigma not exserted beyond anthers; petals 5–15 mm. (39)

+ Stigma exserted beyond anthers; petals 10–30 mm. (41)

39 (38) Stems erect; leaf blades usually linear to lanceolate, apex acute 22 Clarkia purpurea (in part)

+ Stems prostrate to decumbent; leaf blades elliptic to oblanceolate, apex usually obtuse. (40)

40 (39) Petals 5–11 mm, without spot 20 Clarkia davyi

+ Petals 10–15 mm, with red spot above base 21 Clarkia prostrata

41 (38) Inflorescences dense; ovary at anthesis longer than adjacent internode. (42)

+ Inflorescences open; ovary at anthesis shorter than adjacent internode. (43)

42 (41) Floral tube conspicuously veined; petals with large, wedge-shaped purplish red spot near apex 17 Clarkia imbricata

+ Floral tube not conspicuously veined; petals with red spot near or proximal to middle 19 Clarkia speciosa (in part)

43 (41) Buds mucronate, sepal tips distinct in bud 18 Clarkia williamsonii

+ Buds not mucronate, sepal tips connate to tip. (44)

44 (43) Petals without red or red-purple spot 19 Clarkia speciosa (in part)

+ Petals with conspicuous red or purple spot. (45)

45 (44) Petal spot at or proximal to middle 19 Clarkia speciosa (in part)

+ Petal spot distal to middle 22 Clarkia purpurea (in part)

List of lower taxa