Page:Transactions of the Natural History Society of Northumberland, Durham, and Newcastle-upon-Tyne (1867).djvu/321

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LIST OF BALLAST PLANTS.
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following is a list of the more remarkable stranger-plants which from time to time have been gathered on the ballast-hills of the two counties. Their localities are indicated by letters placed in three columns, T. meaning the heaps on the banks of the Tyne, S. those in the neighbourhood of Sunderland, and H. those in the neighbourhood of Hartlepool and the Tees mouth. The list is compiled from Winch's Flora and papers by the Rev. A. M. Norman and Mr. M. A. Lawson in the 5th vol. of our Transactions, with a few additions from other sources. In the countries mentioned in the second column the species are either natives or well-established weeds. Those for which no letters are given are mentioned in Winch's list without any particular locality. We believe that it rarely happens that any of these ballast introductions ripen seed, and spring up a second time, so that when fresh importations cease they disappear speedily. Although we see that this ballast-list includes more than a hundred and fifty species, of the plants mentioned in the body of the work Reseda lutea, Sinapis tenuifolia, Pastinaca sativa, and perhaps three or four of the Chenopodiaceœ are all that are at all likely to have been introduced in this way. As Mr. Lawson has explained in his paper, for the first year or two after the ballast has been laid down the annuals spring up; then these disappear and the perennials succeed them; and, finally, in the struggle for existence, if the heaps become disused, these are crowded out by thistles and wormwood, milfoil and ragwort, Triticum, and Ammophila, and Festuca rubra.