Cerastium alpinum
Cerastium texanum
alpine chickweed, alpine mouse-ear chickweed, céraiste alpin
Chihuahuan mouse-ear chickweed, Texas chickweed, Texas mouse-ear chickweed
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.
erect, sparingly branched proximally, slender, 15–35 cm, sparsely glandular-pilose; 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.
not marcescent;
proximal blades broadly spatulate-petiolate, 8–55 × 3–16 mm, apex acute or obtuse, sometimes short-acuminate, softly pilose;
cauline few, sessile, blade linear-lanceolate to narrowly oblanceolate, 7–30 mm, apex acute, pilose.
open, (1–)2–4-flowered cymes;
bracts lanceolate, acute, margins narrow, scarious, glandular-pubescent.
very open and loose, 2–9(–25)-flowered cymes;
bracts narrowly lanceolate, pilose.
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.
straight, becoming sharply deflexed at base, slender, 5–20 mm, elongating in fruit, 1.5–4 times as long as sepals, glandular-pilose.
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 green, turning pale orange-brown in fruit, lanceolate to ovate, 3–6 mm, margins narrow, apex acute, with short, glandular pubescence;
petals oblanceolate, 5–8 mm, 1.5–2 times as long as sepals, apex 2-fid;
stamens 5;
styles 5.
cylindric, slightly curved, 12–16 mm, to 2 times as long as sepals;
teeth 10, erect, margins convolute.
cylindric, straight, 5–12 mm, 1.5–2 times as long as sepals;
teeth 10, becoming outwardly coiled.
dark brown, 1–1.4 mm diam., acutely tuberculate;
testa not inflated.
red-brown, 0.4–0.7 mm diam., tuberculate;
tubercles ± pointed;
testa not inflated.
= 72, 108.
= 36.
Cerastium alpinum
Cerastium texanum
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 texanum is exceptionally variable in flower and capsule size. The extent to which this variation is due to environmental conditions or is genic in origin is not known. The broad, spatulate basal leaves and the straight, cylindric capsule with its outwardly coiled (revolute) teeth distinguish this species.
(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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