144 FLOWERS OK ROCKS, WALLS, ETC. 



The lioncy-nlands are sitnaletl as in ilic Greater Stilchwort. The 

 stamens and pistil develop in the same manner. A similar i)[)purtuiiity 

 for cross-pollination is presented when insects visit it, and of self- 

 pollination in their absence. The flowers are large and widely open 

 and conspicuous. The insects that visit it are numerous: Diptera, 

 Stratiomyids, Empidae, Pepidce, Syrphidse Erista/is, Syrilta, Plaly- 

 clictrus, Syrphits, Melanostovia, Muscidae, Hymenoptera, Apida;, Cole- 

 optera, Staphylinidae, Thysanoptera, Thrips, Lepidoptera, Polyom- 

 matus ph/a'as. Besides complete flowers there are some w ith more or 

 less rudimentary stamens. 



Field Mouse-ear is mainly dispersed by the wind. The seeds 

 (acLitely tuberculate) are blown out of the capsule, the plant growing 

 in exposed positions. 



It is a sand-loving plant growing on a sand soil, but is also lime- 

 loving, and will subsist on a lime soil. 



A fungus, Melavipsora ceraslii, lives upon it. It is galled by 

 Cecidomyia cerastii. The beetle Adiuionia tatiaceti, and the moths, 

 Coleophora chakogrammella, C. olivacella, (Small Yellow Underwing), 

 Heliodcs arbnti, Heliaca tenebrata, feed on it. 



The second name, arvense, refers to a reputed prevalence for culti- 

 vated land. 



Though found in the eastern counties in cornfields, it is found on 

 dry banks, sand-banks, and on walls, as well as on hilly ground. It is 

 distinguished from all other species by its large flowers, prostrate habit, 

 the deep-green, not light or yellow leaves, its brittle-jointed stem, and 

 its powerful creeping root. 



Essential Specific Characters: — 



53. Cerastium a7i'ense, L. — Stem prostrate, wiry, tufted, lea\-es 

 linear-lanceolate, downy, petals longer than the caly.x, white, bracts 

 membranous on the margin and at the tip. 



Sand Spurrey (Spergularia rubra, Pers.) 



No instance of the occurrence of this plant in Glacial, earlier or 

 later, beds is known at present. To-day it is found in the Temperate 

 Northern Zone in Europe, North Africa, Siberia, Western Asia to 

 India, North America. In Great Britain it is common, but absent in 

 West Suffolk, Montgomery, Flint, Ro.xburgh, Westerness, Cantire, 

 South Ebudes, Mid Ebudes, North Ebudes, Sutherland, Caithness, 

 and the Northern Isles. In Ireland it is quite rare. 



Sand Spurrey is a plant of rocky districts where there are accumu- 



