1858.] ON MURAL OR WALL PLANTS. 531 



It is idle to speculate about the agencies whereby the seeds may 

 have been conveyed from the garden to the garden- wall ; this is 

 not the point. What I wish to establish is, that they were 

 transported from the garden, and not from a distant country. 

 Another point is also forced upon us, viz. that, even in the south 

 and centre of Europe, both these plants are described as garden 

 plants, or as located on garden-walls. In the ' Flore d^ Alsace ' 

 both species have the same habitats, viz. '^jardms, murs." In 

 the German Flora the habitat of D. Caryophyllus is thus stated : 

 " In Garten als eine sehr gewiirzhaft riechende Blume haufig 

 kultivirt " (cultivated in gardens as a very odoriferous flower) ; 

 that of D. plumarius as follows : " Auf Kalkfelsen, Sandhiigeln, 

 etc., in Niederosterreich. In Garten als schone Zierpflanze kul- 

 tivirt" (on limestone rocks and sandhills in Lower Austria; 

 cultivated in gardens as a very ornamental plant). In Grenier 

 and Godron's ' Flore de France,' D. Caryo'phyllus is said to be 

 found "sur les vieux chateaux et les murs en ruines des pro- 

 vinces de I'ouest, depuis Bayonne jusqu'au Falaise :" the pre- 

 cise habitats where the plant is found among ourselves, only it is 

 not so extensively distributed here as in France. The limestone 

 rocks and sandhills of Austria are the only natural habitats for 

 J), plumarius, and there are none for D. Caryophyllus from the 

 south to the north of Europe. Are they European, or African, 

 or Asiatic plants? Or are they, like Borago officinalis, Antir- 

 rhinum ma jus, Linaria Cymbalaria, and several other plants, 

 "terrse nullius adstrictse," fugitives, and disowned by every land? 

 Examples need not be multiplied, yet they are useful to teach us 

 caution in adjudicating on the claims of the nativity of plants. 

 The example however of Sinapis tenuifolia is instructive. This 

 plant, in the valley of the Thames, especially at no great distance 

 from the river, is very common. And here it may be called a 

 viatical plant, viz. growing about waysides, waste places, and on 

 rubbish. Here it is rarely noticed on walls. (Is it ever ?) The 

 Wallflower here is the common ornament of walls. The Sinapis, 

 however, adorns the old wall or portions of the old wall at South- 

 ampton, and it is said to be the common mural plant of the an- 

 cient city of Chester. Its name Wall- Rocket indicates its mural 

 habitat. It would be worth while to notice if in those places 

 where it grows on walls it shuns the ground. Diplotaxis muralis 

 is rapidly extending its area in this neighbourhood (London), but 



