Cerastium pumilum
Cerastium viride
dwarf mouse-ear, dwarf mouse-ear chickweed, European chickweed, sticky mouse-ear chickweed
field chickweed, western field mouse-ear chickweed
erect or ascending, branching near base, 2–12 cm, covered with glandular and eglandular hairs; small axillary tufts of leaves usually absent.
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.
not marcescent, sessile;
blade 5–15 × 3–6 mm, hairy;
basal with blades oblanceolate, spatulate, petiolelike, apex obtuse;
cauline with blades lanceolate, elliptic, or ovate, apex acute to obtuse.
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.
lax, 3–15-flowered (rarely more) cymes;
bracts lanceolate: proximal usually foliaceous, distal smaller, usually with narrow, scarious margins and apex, glandular-pubescent.
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.
erect, curved distally, 3–8(–10) mm, longer than capsule, 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.
sepals green, sometimes red tipped, oblong-lanceolate, 4–5 mm, margins narrow, apex acute, pubescent, hairs short, stiff, glandular, not projecting beyond scarious, glabrous apex;
petals white or purple-tinged, with branching veins, oblanceolate, ca. 5 mm, ± equaling sepals, apex 2-fid for ca. 1/4 length;
stamens 5;
styles 5.
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.
narrowly cylindric, slightly curved upward, 6–9 mm, ca. 2 times as long as sepals;
teeth 10, erect, margins convolute.
broadly cylindric, ca. straight, 8–15 × 4–5 mm, 1.5–2 times as long as sepals;
teeth 10, erect, margins convolute.
dark brown, deltoid, 0.6–0.7 mm, tuberculate;
testa not inflated.
reddish brown, 1–1.5 mm, tuberculate;
testa not inflated, tightly enclosing seed.
= 72.
= 72.
Cerastium pumilum
Cerastium viride
North American material referred to here as Cerastium pumilum is very variable. At one extreme are plants resembling small annual forms of C. fontanum, with relatively short, broad capsules, petals slightly longer than the sepals, and sepals that are usually red at the tips. At the other extreme are plants with relatively long, narrow capsules resembling impoverished diffuse-inflorescenced C. glomeratum, with short petals and no red pigment. The latter are probably referable to C. pumilum subsp. glutinosum. B. Jonsell and T. Karlsson (2001+, vol. 2) treated C. glutinosum as a distinct species in Scandinavia, but the correlation of characters that they gave to distinguish C. glutinosum from C. pumilum does not occur in most North American material that I have examined. Hence, the recognition of a single species, possibly with two subspecies, as in Flora Europaea (T. G. Tutin et al. 1964–1980, vol. 1), appears to be more appropriate. The problem may arise from North American material having been introduced from several sources, whereas Scandinavian material may consist of two native genotypes that do not show the complete range of variation in the species.
Cerastium pumilum can look like a small annual form of C. fontanum but differs in its smaller capsules and the characteristic rather short, glandular hairs on the sepals, bracts, and inflorescence. It can be separated from C. semidecandrum by the much narrower scarious margins of the sepals and bracts and by the branching veins in the petals, which tend to be slightly longer and more conspicuous than in C. semidecandrum. Some forms of C. glomeratum have a very open inflorescence and may be confused with C. pumilum, but C. glomeratum has ten stamens, a narrower capsule, all the bracts herbaceous, and long, eglandular hairs (often mixed with glandular ones) on the bracts and sepals.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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.)
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