44 
CERASTIUM 
Section I. ORTHO DON 
Orthodon [Seringe mss, ex] DC. Prodr. i, 415 (1824); Rouy et Foucaud FI. France iii, 202 (1896). 
For characters, see page 43. 
British series of Orthodon 
Series i. Alpina (see below). Perennial. Shoot with long fertile branches and shorter barren 
branches. Flowers pentamerous. Petals longer than, usually about twice as long as the sepals. 
Stamens n + n (n = 5). 
Series ii. Viscosa (p. 50). Annual. Shoot with no barren branches. Flowers pentamerous 
or tetramerous. Petals about as long as, or a little shorter than, the sepals. Stamens usually n , rarely 
more (n = 5 or 4). 
Series i. Alpina 
Alpina Moss in Camb. Brit. FI. iii, 44. 
I here include C. arcticum in this series, although, as a matter of fact, it is really a connecting link between the series 
Alpina and a series including C. latifolimn L. (non Sm.), which otherwise is not represented in the British flora. 
For characters, see above. 
British species and hybrids of Alpina 
1. C. arvense (see below). Shoot usually more or less pubescent. Laminae linear-lanceo- 
late. Inflorescence with several flowers. Petals much longer than the sepals. Seeds tuberculate ; 
testa close-fitting. 
2. C. alpinum (p. 46). Shoot (in the British form) covered with long, white, soft hairs. 
Laminae broadly oval or elliptical. Inflorescence usually with 1—2 flowers. Petals much longer than 
the sepals. Seeds acutely tuberculate ; testa close-fitting. 
C. alpinum x arcticum, (p. 46)- Shoot pubescent. Laminae narrowly elliptical. Flowers and 
seeds intermediate between those of the putative parents. 
C. alpinum X vulgatum (p. 47). Intermediate between the putative parents, as seen specially in 
the inflorescence. 
3. C. arcticum (p. 47). Shoot covered with rather stiff yellowish hairs. Laminae oval or 
elliptical. Inflorescence usually with 1 — 2 flowers. Petals much longer than the sepals. Seeds large 
(nearly 3 mm.), tuberculate ; testa rather loose. 
C. arcticum, x vulgatum (p. 48). Intermediate between the putative parents. 
4. C. vulgatum (p. 48). Shoot usually pubescent. Laminae rather narrowly elliptical. 
Inflorescence with several flowers. Petals longer than or (in the common form) only as long as the 
sepals. Seeds punctate. 
I. CERASTIUM ARVENSE. Field Chickweed. Plate 43. 
Caryophyllus holostius Gerard Herball 477 (1597); Auricula muris pulchro flore albo J. Bauhin Hist, iii, pt. 2, 
360 (1651); Ray Cat. Cantab. 19 (1660); Caryophyllus arvensis hirsutus flore majore C. Bauhin Pinax 210 (1671); 
Ray Syn. ed. 3, 348 (1724). 
Cerastium arvense L. Sp. PL 438 (1753)!; Smith Eng. Bot. no. 93 (1793); FI. Brit. 499 (1800)!; 
Syme Eng. Bot. ii, 88 (1864); Rouy et Foucaud FI. France iii, 202 (1893); C. mutabile [subsp.] arvense Grenier 
Monogr. Cerast. 68 (1841). 
Perennial. Shoot straggling, procumbent, rooting freely, usually more or less pubescent, branches 
c — 30 cm. long. Laminae linear-lanceolate, about 2 cm. long and 3 mm. broad. Inflorescence lax, 
with 3 — !3 flowers. Bracts lanceolate, with scarious margins, much smaller than the leaves. Pedicels 
at maturity 2 — 4 times as long as the calyx. Flowers 10 — 18 mm. in diameter; April to July. Sepals 
narrowly ovate, with scarious margins. Petals about twice as long as the sepals. Capsule a little 
longer than the calyx. Seeds reddish-brown, with small but conspicuous tubercles ; testa close-fitting. 
(a) C. arvense var. angustifolium Fenzl in Ledebour FI. Ross, i, 413 (1842); Rouy FI. France iii, 202 (1896) ; 
Centunculus angustifolius Scopoli FI. Carn. ed. 2, i, 322, t. 19, fig. 551 (1772); C. arvense var. pubescens Syme Enr. 
Bot. ii, 89 (1864). 
