A HISTORY OF NORTHAMPTONSHIRE less the substitution of coal for wood as a fuel has also had influence in diminishing the number of mural plants in towns. With the destruction of the Old Castle at Northampton disappeared in its only known locality in the county the wall rocket [Diplotaxis tenuifolia), and with it also went from that locality several interesting species including Galium erectum. The Northampton racecourse which within the last fifty years had rough banks and hollows on it, and yielded the garlic [Allium vineale), meadow saxifrage [Saxifraga granulatd) and other plants, has but few and those the commonest species now. Although the changes hitherto mentioned in the character of the vegetation of the county have been all for the worse, yet it must be acknowledged that perhaps in the number of species the nineteenth may compare quite favourably with the ninth century. The large extent of country under the cultivation of corn has brought in, although doubtless a very long time ago, a considerable number of agrestal species which are probably not indigenous to Britain. Among these plants, which we call colonists, are the poppies {Papaver Rhceas^ P. dubium, and P. Arge- mone), the fumitory (Fumaria officinalis)^ the white mustard {Brassica alba), the shepherd's needle {Scandix Pecten-veneris), the hare's ear [Bupleurum rotundifolium), the corn marigold [Chrysanthemum segetum), the corn buttercup {Ranunculus arvensis), the corn cockle [Lychnis Gith- ago)y the St. Barnaby's thistle [Centaurea Solsfitialis), the blue cornflower [Centaurea Cyanus), the Venus' looking-glass [Specularia hybrida), the field bugloss [Anchusa arvensis), the corn gromwell [Lithospermum ar- vense), the small toad-flax [Linaria minor or viscida), the calfs snout [Antirrhinum Orontium), the grey speedwell [Veronica didyma or polita), and other species ; the upright ground ivy [Stachys arvensis), the hemp nettle [Galeopsis speciosa or versicolor), the red cut-leaved archangel [Lamium hybridum), several of the goosefoots [Chenopodium), the corn bindweed [Polygonum Convolvulus), the sun spurge [Euphorbia helioscopia), the petty spurge [E. Peplus), the corn spurge [E. platyphylla), and several species of grass such as Avena strigosa znA fatua, Bromus secalinus, and the darnel [Lolium temulentum). But in addition to these we have plants introduced to our cultivated areas in more recent times ; among them the blue-flowered Veronica Tournefortii, or as it has also been called V. Buxbaumii, which was not known to occur in this country in the eighteenth century, but is now very widely distributed. The clover dodder [Cuscuta trifolii) and the hoary cress [Lepidium Draba) also were unknown in Britain before the nineteenth century. There is more doubt as to the date of the introduc- tion of the two hawkweeds, Crepis biennis and C taraxacifolia, and many botanists believe them to be indigenous in the eastern counties, and that they belong to the Germanic type of distribution. This may possibly be a correct view, but the extraordinary manner in which they have increased in recent years is evidence to me that in a large number of instances these plants, especially the latter species, are colonists rather than indigenous. Within my recollection these plants have been intro- 54
