Cerastium fontanum |
Cerastium alpinum |
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common chickweed, common mouse-ear chickweed, céraiste commun, mouse-ear chickweed |
alpine chickweed, alpine mouse-ear chickweed, céraiste alpin |
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Habit | Plants perennial (rarely annual), tufted to mat-forming, often rhizomatous. | Plants perennial, mat-forming, rhizomatous. | ||||||||
Stems | flowering stems erect from decumbent base, branched proximally, 10–45 cm, softly pubescent, eglandular with straight hairs; nonflowering shoots, when present, produced proximally, decumbent, rooting at nodes, branched, 5–20 cm, often subglabrous with alternating lines of eglandular hairs; small axillary tufts of leaves usually absent. |
prostrate or ascending, tomentose (very rarely subglabrous), hairs white, translucent, long, soft, flexuous, some usually also short and glandular; flowering shoots ascending, 5–20 cm; small axillary tufts of leaves usually absent; nonflowering shoots ± prostrate, to 6 cm. |
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Leaves | not marcescent; blade 10–25(–40) × 3–8(–12) mm, densely covered with patent to ascending, colorless, long, eglandular hairs; leaves of flowering shoots in distant pairs, sessile, blade elliptic to ovate-oblong, apex subacute; leaves of sterile shoots pseudopetiolate, often spatulate, blade oblanceolate, apex obtuse. |
marcescent or not, sessile; blade obovate or ovate to elliptic-oblanceolate, elliptic, or lanceolate, usually 10–18 × 5–7 mm, apex obtuse, pubescence as on stems. |
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Inflorescences | lax, 3–50-flowered cymes; bracts lanceolate, reduced, herbaceous, eglandular-pubescent, distal often with narrow, scarious margins. |
open, (1–)2–4-flowered cymes; bracts lanceolate, acute, margins narrow, scarious, glandular-pubescent. |
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Pedicels | somewhat curved distally, 2–10(–20) mm, longer than sepals, densely pubescent with patent, eglandular, rarely glandular hairs. |
straight but often becoming angled at base and curved at apex, slender, 5–30 mm, often elongating to 3 or 4 times as long as sepals, pubescence usually dense, hairs both long, flexuous, multicellular, and short, glandular, viscid. |
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Flowers | sepals ovate-lanceolate, 5–7 mm, margins narrow, apex acute, scarious, pubescent with eglandular, rarely glandular, hairs; petals oblanceolate, 1–1.5 times as long as sepals, apex deeply 2-fid; stamens 10, occasionally 5; styles 5. |
sepals green, often violet tipped, narrowly elliptic-lanceolate, 7.5–10 mm, margins ± narrow, apex acute to obtuse, densely pubescent, hairs both long, eglandular and short, glandular; petals 1–2 times as long as sepals, apex shallowly 2-fid; stamens 10; styles 5. |
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Capsules | narrowly cylindric, curved, 9–17 mm, ca. 2 times sepals; teeth 10, erect, margins convolute. |
cylindric, slightly curved, 12–16 mm, to 2 times as long as sepals; teeth 10, erect, margins convolute. |
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Seeds | reddish brown, 0.4–1.2 mm, bluntly tuberculate; testa not inflated, tightly enclosing seed. |
dark brown, 1–1.4 mm diam., acutely tuberculate; testa not inflated. |
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2n | = 122–152, usually 144. |
= 72, 108. |
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Cerastium fontanum |
Cerastium alpinum |
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Distribution |
AK; AL; AR; AZ; CA; CO; CT; DC; DE; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; NC; ND; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SC; SD; TN; TX; UT; VA; VT; WA; WI; WV; WY; AB; BC; MB; NB; NS; NT; ON; PE; QC; SK; YT; Europe [Introduced elsewhere]
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MB; NT; NU; ON; QC; SK; Canada; Greenland; Europe (Iceland, Scandinavia)
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Discussion | Subspecies 4 (2 in the flora). Cerastium fontanum is a highly variable and complex species. It often has been reported as C. vulgatum Linnaeus, an ambiguous name; see discussion under the genus. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Subspecies 3+ (2 in the flora). The Cerastium alpinum group of species is a difficult complex of intergrading taxa. E. Hultén (1956) considered this complex to be the result of worldwide introgression among the various taxa. Members of this group in North America include C. aleuticum, C. alpinum, C. arcticum, C. beeringianum, C. bialynickii, C. fischerianum, C. regelii, and C. terrae-novae. Cerastium alpinum itself is distinguished from all other members of the complex by its lanate pubescence, which consists of long, silvery, translucent, multicellular, flexuous, often tangled hairs; the more or less square base of the calyx; the convex margins of the sepals; and, in well-grown plants, the long, slender, divaricate pedicels. In western North America, Cerastium alpinum is replaced by C. beeringianum, which has long, straight, strigose, somewhat fuscous hairs, usually smaller flowers, and smaller seeds. The two species intergrade in eastern Canada; intermediate specimens were named C. alpinum var. strigosum Hultén. Cerastium arcticum differs from C. alpinum, with which it often grows, in its straight, somewhat fuscous hairs; calyx which is round at the base; long, narrowly lanceolate sepals; large, straight, broad capsules; and broad, obtuse cauline leaves. Like C. alpinum, it usually has large flowers with the petals much longer than the sepals. Many infraspecific taxa have been named in Cerastium alpinum but in North America it is much less variable than elsewhere. Two forms can be recognized at either the varietal or subspecific level. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 5. | FNA vol. 5, p. 77. | ||||||||
Parent taxa | Caryophyllaceae > subfam. Alsinoideae > Cerastium | Caryophyllaceae > subfam. Alsinoideae > Cerastium | ||||||||
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Subordinate taxa | ||||||||||
Name authority | Baumgarten: Enum. Stirp. Transsilv. 1: 425. (1816) | Linnaeus: Sp. Pl. 1: 438. (1753) | ||||||||
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