Cerastium viride
Cerastium arcticum
field chickweed, western field mouse-ear chickweed
arctic mouse-ear chickweed, céraiste arctique, mouse-ear chickweed
flowering stems ascending from elongate decumbent bases, branched, 15–45 cm, viscid, glandular in distal and mid-stem region, proximal portion with deflexed, long, soft, eglandular hairs, mostly in alternating longitudinal lines; nonflowering shoots horizontal, leafy.
erect, from decumbent base, 5–30 cm, sparsely to densely pubescent, hairs spreading, straight, often glandular; small axillary tufts of leaves usually absent.
sometimes marces-cent, sessile, highly variable;
blade tending to be succulent, pubescent on both surfaces or ± glabrous abaxially except on midrib and margins;
leaves of mid and distal stem largest, blade ovate-lanceolata to linear-lanceolate or narrowly oblong, 15–42 × 3.5–7 mm, apex acute;
proximal leaves smaller, with tufts of small leaves in their axils, blade oblanceolate to linear-oblong, 10–30 × 2–7 mm, often spatulate, apex ± obtuse.
subsessile;
blade broadly elliptic to obovate or rotund, larger blades in mid-stem region, 5–22 × 2–8 mm, apex round and obtuse, rarely broadly acute, pubescence ciliate and strigose, hairs long and eglandular, mixed with shorter eglandular hairs, colorless to somewhat fuscous;
proximal leaves not strongly marcescent, blade oblanceolate, often broadly so, spatulate.
lax, 1–12-flowered cymes;
bracts glandular-pubescent, proximal bract often foliaceous, broadly lanceolate to ovate-lanceolate;
distal bracts lance-elliptic to lanceolate, margins narrow, scarious.
1–3-flowered, lax cymes, with patent, multicellular, long, glandular hairs;
proximal bracts broadly lanceolate, pubescence as leaves;
distal bracts narrowly lanceolate, margins narrow, scarious, glandular-pubescent.
straight or sometimes curving near apex in fruit, tending to be stout, 10–35 mm, ca. 2–4 times as long as capsules, rarely more, pubescence dense, glandular, viscid.
± straight or somewhat curved at apex, 5–45 mm, 1–4 times as long as sepals (rarely longer), pubescence long and glandular.
large and showy;
sepals lanceolate, 6–9 mm, margins broad, apex acute, densely glandular-pubescent, viscid;
petals broadly oblanceolate, large, 10–15 mm, 2–3 times as long as sepals, apex 2-fid;
stamens 10;
anthers 0.9–1.2 mm;
styles 5.
sepals narrowly lanceolate, 8–11 mm, margins narrow, apex acuminate, hairs ascending, long, glandular and eglandular;
petals 12–18 mm, 1–2 times as long as sepals, apex 2-fid;
stamens 10;
styles 5.
broadly cylindric, ca. straight, 8–15 × 4–5 mm, 1.5–2 times as long as sepals;
teeth 10, erect, margins convolute.
broadly conic, straight or almost so, 14–18 mm, 1.5–2 times as long as sepals, teeth 10, ± erect, margins convolute.
reddish brown, 1–1.5 mm, tuberculate;
testa not inflated, tightly enclosing seed.
red-brown, 1.1–1.3 mm diam., tuberculate;
tubercles acute;
testa not inflated, closely enclosing seed.
= 72.
= (54) 108.
Cerastium viride
Cerastium arcticum
Some forms of Cerastium viride can be difficult to distinguish from larger forms of C. arvense subsp. strictum, but the broader capsule and leaves usually are diagnostic. In rare cases, chromosome number or pollen size [38–70 (average 43) µ in C. viride versus 28–40 (average 34) µ in C. arvense subsp. strictum] may be needed to confirm identification. Some of the inland material from Catsop County, Oregon, is atypical in having more slender pedicels, longer and softer pubescence, and more acute sepals.
Cerastium viride often has been treated as a variety or subspecies of C. arvense. It differs from the native C. arvense subsp. strictum in being much larger in all its parts, and in chromosome number (2n = 72 in C. viride, 36 in C. arvense subsp. strictum). The two taxa do not hybridize in the wild and attempts to cross them in cultivation have failed. The introduced C. arvense subsp. arvense may be confused with C. viride. Both are strongly rhizomatous and the ranges of measurements for key characters overlap. However, the two taxa have different appearances, C. arvense subsp. arvense being a more slender plant with narrow leaves that are never succulent. In contrast, C. viride tends to be larger in all its parts, with sturdier, decumbent stems, and usually succulent leaves.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Cerastium arcticum has been a much confused and misunderstood species, recently separated from C. nigrescens Edmonston ex H. C. Watson on seed characters. The latter has large seeds with loose, inflated testae, whereas C. arcticum has seeds that are smaller and have tight testae that cannot easily be removed (A. K. Brysting and R. Elven 2000). Much of the North American material previously placed in C. arcticum is now considered to belong to a distinct species, C. bialynickii Tolmatchew (see comments under that species). Cerastium alpinum differs from C. arcticum in having very long, flexuous, translucent hairs which often mat together. In C. arcticum and other members of the complex, the hairs are usually straight, yellowish, and not flexuous. Cerastium arcticum may on occasion have some pubescence like that of C. alpinum; such plants have been named C. arcticum var. vestitum. Whether they represent introgression of C. alpinum into C. arcticum, as suggested by E. Hultén (1956), is uncertain.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
CA
OR
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