1859.] WANDSWORTH PLANTS. 349 



be stated as closely as possible, and also the frequency of the 

 species on the spot, in order to help to an approximation to its 

 numerical statistics. 



3rd. It is always worth while to state the nature of the surface 

 of the ground ; if in tillage, the crop growing thereon ; if on rub- 

 bish, where most of the new plants are seen, what sort of rubbish 

 it is, and the probable place whence the rubbish or soil was 

 derived. 



4th. Historical information, when accessible, is above all most 

 satisfactory. 



For example, there are two plants well-established, known in 

 their present localities at least a century, but neither of them 

 evincing much tendency to spread. The one is Maianthemum 

 bifolium {Convallm'ia bifolia), Linn., only certainly known at 

 Hampstead, in Ken Wood, where it occupies a single spot, 

 slightly enlarged within the last forty years : but thirty years 

 ago there were two patches of it in the same wood, at a con- 

 siderable distance (several hundred yards apart), now there is 

 only one. The other example alluded to is Impatiens fulva, the 

 existence of which was ignored for many years, although the 

 plant was well known. This plant does not appear to increase. 

 Has it been seen out of Surrey, or in any part of this county 

 except in the vale of the Tillingbourne, the Wey, and the Thames? 

 It is plentiful at Albury, Chilworth, Shalford, and Guildford. 

 At Shere, which is not above a stone's-throw from Albury Park, 

 the cradle of this Balsam, there is not one plant. At Godalming, 

 on the Wey, only two miles from Shalford, there is none of it. 



Finally, the primary objects to be ascertained are, is the species 

 truly spontaneous? Next, has it been produced from seeds, 

 ripened in the place where it is observed ? This last is not very 

 material ; for if garden plants produce seeds capable of germina- 

 tion and reproduction, fields under certain conditions may also 

 produce productive seeds. Does the species cover or grow on a 

 considerable space of ground ? And, how long has it been ob- 

 served to appear there ? A plant may have all the appearance 

 of an aboriginal, or at least of some so called, and it may not have 

 been seen here before. A striking example of this was observed 

 at Guildford thirteen years ago. Nicandra physaloides appeared 

 over a space of scores of acres of cultivated land, as well as in 

 some gardens. It was never observed there before, and probably 

 has not been seen since. 



