A. H. Trow 269 



absence (/) may then represent the yellow-green colour. It is note- 

 worthy that in one culture of hybrids of Senecio sylvaticus x 8. viscosus 

 — a species hybrid — a number of seedlings with white cotyledons were 

 observed, which of course soon perished. It is probable that the occur- 

 rence of these marked the segregation of another leaf colour character, 

 one which is very likely to occur in Senecio vulgaris also*. 



The most exacting and perhaps most interesting work of the last 

 five years, consisting of a long and very tedious series of measurements 

 of the vegetative organs, still remains to be discussed, but must form ' 

 the basis of a second contribution to our knowledge of the common 

 groundsel. 



Summary. 



The common groundsel, Senecio vulgaris, Linn., is an aggregate 

 species which has been found to include many segregate or ele- 

 mentary species. 



Twelve of these elementary species have been cultivated and main- 

 tained pure and true to type for at least several generations. Six of 

 them have been studied in detail, and are distinguished by more or less 

 descriptive names — praecox, erectus, multicaulis, latifolius, genevensis 

 and lanuginosus. Of these lanuginosus is radiate, the other five non- 

 radiate. Lanuginosus was obtained from the Channel Islands, ^enere/wi* 

 was collected in the vineyards near Montreux, and the others were 

 found in the neighbourhood of Cardifi". Another form, collected near 

 Cardiff and equally well studied, is erectus, radiatus — the radiate variety 

 of erectus. Five other forms have proved true to type in cultures, but 

 have been so incompletely studied that they are for the present simply 

 designated with their place of origin — all Glamorgan localities: (1) Car- 

 diff, (2) Burry Green, (3) Horton, (4) Cross Common, and (5) St Bride's. 



It has been shewn by experiment that the radiate character of 

 erectus, radiatus can be transferred by hybridization and subsequent 

 segregation to praecox, multicaulis, latifolius and genevensis. A radiate 

 variety of each of these elementary species has in fact been produced in 

 this way, and is now being cultivated. In multicaulis there are at least 

 three kinds of radiate varieties, with yellow, cream and fimbriate florets 

 respectively. Hence, if we accept the usual terminology and persist in 

 regarding S. vulgaris as the species, we have to make varieties of 



* This prophecy was fulfilled in 1912. Seedlings with white cotyledons were observed 

 in the F^ and F4 generations of the cross lanu^inosut x praecox. 



Joorn. of Gen. 11 19 



