ALIEN PLANTS NEAR WOOLWICH. 871 



Arsenal), Phalaris canadensis, and ten or a dozen others, nor obvious 

 garden or cultivation escapes like Borage officinalis, Calendula offici- 

 nalis, &c. The nomenclature followed is that of the London 



Catalogue: — 



Alyssum incanum L. Crossness, and Plum Lane brickfields. 



Sisymbrium pannonicum Jacq. A few plants in Wickham Lane 

 brickfields, and in great abundance in Woolwich Arsenal. I first 

 observed it four or five years ago, only seeing a plant or two ; but 

 it has very rapidly increased, and many hundred plants are now to 

 be found. There is a peculiarity in the whole of the plants I have 

 seen, which retains its characters in plants grown from seed in 

 garden soil, namely, that the petals, which are represented in 

 Jacquin's figure in Ic. Plant. Bar. as being quite half an inch long, 

 are in the Woolwich plant shorter than and much narrower than the 

 calyx, and much the same colour, so that at first sight the flowers 

 appear apetalous. Late in the season, the petals, even in just 

 opening flowers, seem to disappear altogether, but Mr. Scott 

 Elliot, to whom I sent some specimens, says that he could detect 

 the claw only of the petals, green, and adherent to the sepals. 

 The form is quite constant, and seems worthy of study. 



Erysimum orientals R. Br. Eight or ten plants on some newly 

 turned soil in Woolwich Arsenal. These are specially interesting 

 on account of their associates, viz., Silene maritima in some quantity, 

 and one plant of Cakile maritima. The soil is dredged river gravel, 

 and had been taken from another spot in making foundations for 

 some new buildings, where it had lain two or three feet below 

 the surface since about the year 1800, when the present river- wall 

 was built. I know of no record, nor even a suitable locality for 

 Cakile maritima nearer than Canvey Island, fifteen miles down the 

 river; and Silene maritima has not, I believe, occurred above 

 Southend. Though it is possible that the seeds were carried up by 

 the tide, I think it is more probable that the soil was dredged from 

 somewhere near the localities indicated. In either case the seeds 

 must have lain dormant for over ninety years. 



Camelina sativa Crantz. Occasional in Woolwich Arsenal and 



elsewhere. . 



Lepidium virrjinicum L. Two plants five years ago m the Arsenal, 



now built on. 



Bunias orientaJis L. 



Woolwich 



and here and 



Saponaria Yaccaria L. Ash-heap in Plum Lane brickfields, in 



some quantity. . £ ' ' a 



Malm borealis Wallm. Crossness, on the dredged mud. 

 Melilotus officinalis Desv. Arsenal, Crossness, Docks, and Plum 



Lane and Wickham Lane brickfields. Apparently much commoner 



Thuill 



-non 



j. Seven or eight plants on some ashes 



recently spread on 'some waste ground in the Arsenal to a depth of 

 ten or twelve inches. The ashes, I believe, were the product of 

 Arsenal furnaces, so the seeds must have been self-sown. 



2 b 2 



