Description of the behaviour of a variety of the potato during the third and fourth years of its life, a variety which I have named Black Seventy Five.¹

“Black Seventy Five” being a description of the life of a variety of the potato during its third and fourth years of life by J. Torbitt | Belfast.

It first attracted my attention in the summer of 1877. It was growing among some hundreds of varieties each like itself, the the product of a seed sown in the spring of 1875. It came first into bloom, the flowers being very large, petals pale lilac, it gave out a rich perfume and was assiduously visited by the humble bee, the insect always passed along the line of plants never omitting one, and never visiting more than one flower—on each plant. The leaves were dark green and very large compared with old varieties, very long and very broad compared with their length, the stems were very thick, of a rather pale green tinged with brown on the lower parts. It produced a large crop of berries and of tubers neither of which was weighed. When ripe I had it raised, and for purpose of crossing, kept it under lock, and planted it last season (1878)  When it came up and as it was growing I found here and there, a plant of a different character from the original; smaller, narrower leaves, stems smaller and browner, and as the plants grew, more and more of them so changed, until at last about one half of the whole variety was so affected. On coming into bloom the changed plants produced small flowers with red petals, had no perfume, the flowers dropped off and the crop of fruit was absent. The tubers were smaller and of less aggregate weight than the tubers of the less changed plants of the variety. The specimens marked Black seventy fives No 2 are tubers of these so changed plants.

The unaltered plants of the variety produced a crop of berries at the rate of 13 tons per acre, and of tubers 11 Tons. The specimens marked Black seventy fives No 1 are the produce of these plants.

Now I would respectfully suggest that, if possible, these black seventy fives No 1, be grown at Kew year after year (say 10 tubers each year) and the result noted.²

Signed | James Torbitt

Belfast 1 May 1879