144 FLOWERS OF ROCKS, WALLS, ETC. 



The honey-glands are situated as in the Greater Stitchwort. The 

 stamens and pistil develop in the same manner. A similar opportunity 

 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, 

 Stratiomyidie, Empidae, Pepidae, Syrphidae Eristalis, Syritta, Platy- 

 cheirus, Syrphus, Melanostoma, Muscidse, Hymenoptera, Apidae, Cole- 

 optera, Staphylinidae, Thysanoptera, Tkrips, Lepidoptera, Polyom- 

 matits phlceas. Besides complete flowers there are some with more or 

 less rudimentary stamens. 



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

 (acutely 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, Melampsora cerastii, lives upon it. It is galled by 

 Cecidomyia cerastii. The beetle Adimonia tanaceti, and the moths, 

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

 Heliodes arbuti, 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 arvense, L. Stem prostrate, wiry, tufted, leaves 

 linear-lanceolate, downy, petals longer than the calyx, 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, Roxburgh, 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- 



