MR. A. W. SUTTON ON BRASSICA CROSSES, 331 
РА 
Bprassrca Crosses. Ву Автнок W. Sutton, F.L.S. 
(PLATES 24—35.) 
[Read 16th January, 1908.] 
In 1899 I was attracted to the study of crosses among species and varieties 
of Brassicas by а statement in one of the leading agricultural journals that 
certain types mentioned by the writer do not hybridize naturally, and 
therefore ean be grown in close proximity to each other witbout fear of 
destroying the highly selected forms which the seedsman is at so much pains 
to keep true. 
Аз experience gained during many years” association with practical seed- 
growing convinced me that the statement was incorrect, I decided to put the 
matter to a practical test in order to place on record the results obtained, and 
to show which species and varieties of Brassica would intercross and which 
would not. 
In the first experiments, begun in 1900, the varieties of Brassica oleracea, 
L., shown in figs. 1 to 9 (Pl. 24), were planted side by side so that cross- 
fertilization might take place wherever such was possible. (For names of 
these varieties see list on page 347.) 
The seed saved from these plants gave rise to ап extremely heterogeneous 
collection of nondescript forms, few or none of which were true to the female 
parental type. Various types, however, were noticed which there was every 
reason to believe would, if it were possible to perpetuate them, become 
valuable additions to the economie plants of the farm or garden. From 
these the forms represented in figs. 10, 11, 12, & 18 (Pl. 25) have been 
fixed, and come fairly true from seed. 
In a later season the experiment was repeated with the addition of varieties 
of Turnips (Brassica Кара, L.), Swedes (Brassica campestris, L., var. Napo- 
brassica, DC.), and non-bulbing oil-yielding Rape (Brassica campestris, var. 
oletfera, DC.). 
Instead, however, of all being planted in one large patch, they were 
arranged in small isolated groups of seven plants each. Two of the plants 
were of one variety, and round them were placed five of another kind. In 
this manner about twenty such double combinations were arranged and the 
seed saved and grown. 
A large collection of mongrel plants was obtained; the results were 
entirely in accordance with my previous experience, and proved that while 
no variety derived from Brassica oleracea was aftected by the pollen of Rape, 
Swede or Turnip, and vice versa, yet all the types of B. oleracea would freely 
intercross between themselves, and this was equally true of many varieties 
of Turnip, Swede, and Rape. 
Hitherto I had been content to note such species of Brassica as would 
LINN. JOURN.—BOTANY, VOL. XXXVIII. 2B 
