20. Cerastium arvense subsp. strictum Gaudin, Fl. Helv. 3: 245. 1828.
卷耳 juan er
Cerastium arvense var. angustifolium Fenzl; C. arvense var. strictum W. D. J. Koch; C. strictum sensu Haenke (1789), not Linnaeus (1753).
Herbs perennial, 15--35 cm tall. Stems sparsely caespitose, creeping proximally, erect distally, retrorsely purplish red hairy, distally both retrorsely hairy and glandular pubescent, or glabrous throughout. Leaves linear to narrowly lanceolate, 0.5--2.5 cm × 1--4 mm, pilose or glabrous, base cuneate, amplexicaul, margin sometimes ciliate, apex acute or acuminate; leaf axils with dwarf, sterile shoots. Cyme terminal, 3--7-flowered; bracts leaflike, lanceolate, pilose, margin scarious. Pedicel 1--1.5 cm, densely white glandular pubescent. Sepals lanceolate, ca. 6 × 1.5--2 mm, abaxially densely villous, margin membranous. Petals obovate, ca. 2 × as long as sepals, 2-lobed for 1/4--1/3 their length. Stamens shorter than petals. Styles 5. Capsule cylindric, ca. 1.3 × as long as calyx, 10-toothed. Seeds numerous, brown, reniform, slightly compressed, tuberculate. Fl. May--Aug, fr. Jul--Sep. 2n = 36.
Sand dunes under forests of Pinus sylvestris var. mongolica, forest margins, sand dune scrub, hillsides, grassy mountain valleys and hilltops, steppes, ditches; 600--4300 m. Gansu, Hebei, Henan, Jiangxi, Jilin, Nei Mongol, Ningxia, Qinghai, Shaanxi, Shanxi, Sichuan, Xinjiang, Yunnan [Japan, Kazakhstan, Korea, Mongolia, Russia; Europe, North and South America].
In FRPS, Cerastium arvense var. arvense was recorded from China, as well as var. angustifolium (a synonym of the widespread subsp. strictum ) and var. glabellum . The identity of Chinese material as subsp. arvense needs confirmation: this taxon is native to W Europe and has been introduced into several other temperate regions, where it grows as a weed in grassy places. Its chromosome number is tetraploid (2 n = 72), as compared with diploid (2 n = 36) in subsp. strictum . These two subspecies are very difficult to separate morphologically, especially in the herbarium, but a chromosome count can provide a strong indication of identity. Cerastium arvense var. glabellum (Turczaninow) Fenzl (in Ledebour, Fl. Ross. 1: 413. 1842, based on C. glabellum Turczaninow, Bull. Soc. Imp. Naturalistes Moscou 15: 614. 1842) is probably only a glabrous form of subsp. strictum .