Cerastium L.
Mouse-ear Chickweed, Starwort.
Sp. Pl. 437. 1753.
Vegetative morphology. Plants 1.5–30(–45) cm high; vegetatively proliferating by bulbils or fragmentation, or not vegetatively proliferating by bulbils or fragmentation. Taproot present (slender). Caudex absent. Ground-level or under-ground stems horizontal, or not developed horizontally or vertically; rhizomatous, or stoloniferous; elongate, or compact; 0.5–1.5 mm wide. Aerial stems erect, or ascending, or decumbent, or prostrate; glabrous, or sparsely hairy, or densely hairy; stem hairs spreading, or erect, or reflexed. Leaves distributed along the stems, or in a basal tuft. Leaf blade bases cuneate, or attenuate. Blades 4–21(–30) mm long; 1–7.5 mm wide. Blades spreading, or divaricate; herbaceous, or somewhat fleshy; linear, or oblong, or elliptic, or lanceolate, or ovate, or oblanceolate, or obovate, or spatulate; flat; appearing single-veined. Blades adaxial surface dull, or shiny; glabrous, or hairy. Blades adaxial surface hairs pilose, or villous, or short-silky; simple, unbranched, or glandular and simple, unbranched; sparse, or moderately dense, or dense; white and translucent. Blades abaxial surface glabrous, or hairy. Blades abaxial surface hairs sparse, or moderately dense, or very dense. Blades abaxial surface pilose, or villous, or strigose. Blades abaxial surface hairs white, or translucent hairs. Blade margins glabrous, or with non-glandular hairs and with glandular hairs. Leaf apices acute, or obtuse.
Reproductive morphology. Plants bisexual, or bisexual and agamospermic. Flowering stems glabrous, or hairy. Flowering stem hairs pubescent, or pilose, or villous. Flowering stems glandular hairs present. Flowering stem hairs white or translucent. Flowers solitary, or in inflorescences. Inflorescence a dichasium. Pedicels bract leaves 2–9 mm long; 0.6–6 mm wide; with a distinct scarious margin, or without a distinct scarious margin. Flowers per inflorescence 1–10(–20); small, less than 5 mm in diameter or length, or medium-sized, 5–15 mm in diameter or length. Calyx base narrowly angled, or widely angled, or rounded. Calyx sepals 5; free; (2–)3.5–9 mm long; (1–)1.2–3.1 mm wide. Calyx green, or green and purple; herbaceous and scarious; hairy; pubescent, or pilose, or villous. Calyx hairs glandular, or glandular and non-glandular; white or translucent. Petals longer than the calyx; 5; white; obtriangular (usually), or obovate, or spatulate; shallowly lobed; 5–10(–13) mm long; 2–7 mm wide. Stamens 10. Anthers yellow; ellipsoid; 0.4–0.9 mm long. Carpels 5 (usually), or 3, or 4. Ovaries oblong. Styles 5 (usually), or 3, or 4; 2–3.5 mm long. Ovules 20–50. Fruit elongate-cylindrical, or oblong, or urceolate; mouth straight, or curved; teeth 10 (usually), or 6, or 8. Fruit 5–16 mm long; 1.5–5 mm wide; straw coloured. Seeds 0.7–1.3 mm long; brown (reddish), or yellowish; with surfaces verrucose, or tuberculate.
Chromosome information. 2n = 38, 72, and 108. Supposed basic chromosome number of family 9.
Distribution. Northern hemisphere distribution: circumpolar and circumboreal; Greenland, Canada, United States, Eurasia.
Illustrations. • Cerastium alpinum. Calyx base narrowly angled; petals longer than the sepals, 2-lobed (the notch 0.2–0.25x the length of the petal); small pedicel bract leaves. Nunavut, Rankin Inlet, 62°48'N, 92°06'W. Aiken and Brysting 01–052. CAN. • Cerastium arcticum. Isolated plant with densely cespitose growth; growing in dry, calcareous gravel. Nunavut, Salliq (Coral Harbour), more recent graveyard, near town on road to the airport, 64°08'13"N, 83°09'53"W. Aiken and Brysting 01–080. CAN. • Cerastium arvense. Inflorescence a dichasium with 3–10 flowers; small bract leaves with a distinct scarious margin. Photo by R. Borge. With permission of the Botanical Museum, University of Oslo, Norway. • Cerastium beeringianum. Inflorescence a dichasium with 2–5(-7) flowers. Nunavut, Southampton Island, Salliq (Coral Harbour), coastline east of the Northern Store, 64°08'13"N, 83°09'53"W. Aiken and Brysting 01–075. CAN. • Cerastium cerastoides. Inflorescence a dichasium with 1–4 flowers; plant all glabrous except for a line of fine glandular hairs at one side of the flowering stems. Norway, Hedmark, Sjusjøen. Photo by R. Borge, July 1971. With permission of the Botanical Museum, University of Oslo, Norway. • Cerastium regelii. Leaves ovate or obovate, glabrous (sometimes ciliated at the margins), somewhat fleshy and shiny; plants in the high Arctic rarely flower. Ellesmere Island, Nunavut, Scoresby Bay, 79°53'N, 71°33'W. Aiken 98–036. CAN. Photograph by Mollie MacCormac.
Cite this publication as: ‘A.K. Brysting, P.J. Scott, and S.G. Aiken 2001 onwards. Caryophyllaceae of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. Version: 29th April 2003. http://www.mun.ca/biology/delta/arcticf/’. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993, 1995, 2000) , and Aiken, Dallwitz et al. (1999) should also be cited (see References).
