378 ECOLOGY 



Waste-heaps, quarry-tips, new embankments, or road- 

 sides, furnish numerous examples of plant invasion and 

 succession ; and the plants of such habitats should be care- 

 fully studied as to their origin, means of dispersal, and 

 increase both by seed and vegetative propagation. 



Native annuals occur along the coast, on the rocks, and 

 on shifting banks ; and some weeds which have somewhat 

 fleshy leaves may have come originally from such habitats, 

 e.g. Fumitory (Fumaria officinalis), Hedge Mustard 

 (Sisymbrium officinale), Charlocks (Brassica Rapa and B. 

 Sinapistrum) , White Charlock (Raphanus Raphanistrum) , 

 Goosefoot (Chenopodium album), Orache (Atriplex patula), 

 Black Bindweed (Polygonum Convolvulus), Knot-grass 

 (P. aviculare), Persicaria (P. Persicaria), all of which are 

 annuals. The Mayweed (Matricaria inodora) is a biennial, 

 and another frequent weed, the Bladder Campion (Silene 

 inflata), is a perennial. Other annuals have doubtless 

 been introduced with impure seed, and those with bright 

 and showy flowers have probably come from sunnier climes, 

 e.g. the Poppies (Papaver Rhoeas and P. dubium), Poor 

 Man's Weather-glass (Anagallis arvensis), and the Corn 

 Marigold (Chrysanthemum segetum). Many have been 

 introduced in this way from North and Central Europe and 

 Asia. 



Other common annuals are : 



Field Buttercup (Ranunculus arvensis), Red Poppy (Papaver 

 Rhoeas), Shepherd's Purse (Capsella Bursa-pastoris) , Corn Pansy ( Viola 

 tricolor), Corn Cockle (Lychnis Githago), Chickweed (Stellaria media), 

 Spurrey (Spergularia arvensis), Soft-leaved Crane's-bill (Geranium 

 molle), Cut-leaved Crane's-bill (G. dissectum), Herb Robert (G. Rober- 

 tianum), Trefoil or Black Medick (Medicago lupulina), Hop Trefoil 

 (Trifolium procumbens), Tare (Vicia hirsuta), Parsley Piert (Alche- 

 milla arvensis), Fool's Parsley (A ethusa Cynapium), Cleavers (Galium 

 Aparine), Field Madder (Sherardia arvensis), Cudweed (Gnaphalium 

 uliginosum), Groundsel (Senecio vulgaris), Sow-thistle (Sonchus olera- 

 ceus), Corn Forget-me-not (Myosotis arvensis), Corn Scorpion Grass 

 (Myosotis versicolor), Ivy-leaved Speedwell (Veronica hederaefolia), 



