370 ON THE THAMES-SIUE BRASSICA. 



It will be evident by this account, that the whole growth of tlie 

 plant, from seedling to ripe seed again, occurs within a single year of 

 time, although it occurs in portions of two difierent solar years, say, 

 the three or four latter months of one year, and the first seven or eight 

 months of the succeeding year. I have not actually tried the experi- 

 ment, but cannot feel any doubt that the whole growing-time might 

 be reduced to six or seven months by collecting the seed in early au- 

 tumn and not sowing it until the succeeding spring. In the latter 

 case it would clearly be an annual ; its biennial character arising only 

 from gradually arrested growth during our winter months. 



Now, as to the affinity of this Thames-side Bransica with the com- 

 mon Turnip, sown as a crop in our gardens and fields. In this year 

 of 1870, at several different dates from February to May, I brought 

 home the living plants from the banks of the Thames and situations 

 adjacent, in order to compare these with beds of garden Turnips at like 

 stages of growth. On a fair general comparison, I have found no dif- 

 ferences between them, such as could be expressed in the technical 

 language of botany, beyond the one obvious difference between the 

 enlarged succulent root of the cultivated Turnip, set against the slen- 

 der fibrous root of that from the Thames. There are, indeed, several 

 varieties of the cultivated Turnip, which practical gardeners and 

 farmers can distinguish from each other ; and so are there slight varia- 

 tions to be seen among the wild examples, which do not vitiate the 

 general similarity, I had made like comparisons occasionally in years 

 past, but specially repeated them this year in order to make assurance 

 doubly sure before again asserting my own view, that the Thames-side 

 Brassica is simply a wild state of the common Turnip, whether an 

 original wild stock or simply become wild. 



Next, as to the difference between the Turnip and the Swede, the 

 latter rather inconveniently and misleadingly called ' Turnip ' also. 

 These differences, once fairly understood, are sufficiently distinctive ; 

 and I regard Turnip and Swede to be species about as distinct from 

 each other as are Swede and Cabbage. The leaves are -too variable in 

 form to afford a clear distinction, but in general those of the Swede are 

 less lyrate and less spreading than are those of the Turnip. The 

 leaves of the Swede are all of them glaucous, — more truly glaucous at 

 all ages of the plant than even the stem-leaves of the Turnip : the 

 upper surfaces of the former are much less rough or bristly than those 



