Cerastium alpinum
Cerastium beeringianum
alpine chickweed, alpine mouse-ear chickweed, céraiste alpin
alpine chickweed, Bering chickweed, Bering mouse-ear chickweed, Bering sea chickweed, Beringian chickweed, céraiste du détroit de Bering
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.
flowering stems usually erect, 10–25 cm, glabrous to sparsely pubescent proximally, more densely so in mid and distal stem, hairs patent to slightly deflexed, multicellular, glandular and eglandular;
internodes usually equaling or exceeding leaves; nonflowering shoots present; small axillary tufts of leaves absent.
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.
sessile (flowering shoots) or petiolate (proximal stems and nonflowering shoots); flowering shoots with blade lanceolate, 5–20 × 2–5 mm, not succulent, apex ± acute, pubescent;
proximal stem and nonflowering shoots with blade oblanceolate often spatulate, not succulent, apex obtuse, ± pubescent on both surfaces (rarely subglabrous), with straight, strigose hairs or cilia, hairs pale, fuscous, mostly eglandular.
open, (1–)2–4-flowered cymes;
bracts lanceolate, acute, margins narrow, scarious, glandular-pubescent.
open, dichotomous, (1–)3–10-flowered cymes;
bracts lanceolate, distal with scarious margins, proximal herbaceous and foliaceous, pubescence glandular and eglandular.
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.
erect, angled at base of calyx in fruit, 8–55 mm, 1–5 times as long as capsule, densely pubescent with patent glandular and eglandular hairs.
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.
sepals lanceolate to lance-elliptic, 3–7 mm, margins broad, apex ± acute, densely glandular-pubescent;
petals broadly oblanceolate, 6–12 mm, ± equaling (rarely to 2 times as long as) sepals, apex deeply 2-fid;
stamens 10;
styles 5.
cylindric, slightly curved, 12–16 mm, to 2 times as long as sepals;
teeth 10, erect, margins convolute.
cylindric, curved, 8–12 mm, ca. 2 times sepals, rarely shorter;
teeth 10, erect, margins convolute.
dark brown, 1–1.4 mm diam., acutely tuberculate;
testa not inflated.
pale to dark brown, 0.7–1.1 mm, tuberculate;
testa not inflated, tightly enclosing seed.
= 72, 108.
= 72.
Cerastium alpinum
Cerastium beeringianum
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.)
Cerastium beeringianum is distinguished from C. alpinum by the absence of the long, silvery, flexuous, translucent, glistening hairs of that species. Cerastium beeringianum’s pubescence consists of straight, strigose, multicellular, somewhat fuscous hairs of several lengths, many of those in the mid and distal stem and inflorescence being glandular and viscid. The nodes and the leaves, at least in the mid and distal stem, typically have long, strigose, eglandular, fuscous hairs; those on the adaxial surface of the leaf being appressed, and those on the nodes retrorse. However, plants from the many small, isolated populations on the mountains of western North America show a great deal of variation. Some of these populations tend to be subglabrous, lacking most of the long hairs normally found on this species. Others are small, delicate plants with slender divaricate pedicels and smaller capsules and seeds. Though names have been given to several of these variants, they frequently intergrade, and much of the variation is greatly influenced by the environment.
Cerastium beeringianum is self-compatible and often self-pollinates, but the flowers are also freely visited by insects, particularly Diptera and smaller Hymenoptera, resulting in varying degrees of outbreeding.
Cerastium beeringianum intergrades with C. fischerianum, and it may be appropriate to treat them as subspecies of a single species. Unfortunately, the name C. fischerianum has priority.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Leaf blades on flowering shoots narrowly elliptic or lance-elliptic to oblanceolate, apex ± acute, pubescence evenly distributed, not very dense; inflorescences usually (1-)2-4-flowered | subsp. alpinum |
1. Leaf blades on flowering shoots lance-elliptic to ovate or obovate, apex obtuse, pubescence a tuft of longer, silvery, ± tangled hairs at apex; inflorescences usually 1-flowered | subsp. lanatum |
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