S. tuberosum L. f. yutuense Buk. et Lechn.


S.Ģ. Bukasov. Potatoes of South America and their breeding use, Leningrad, 1933, p. 89

Diagnosis: Black-purple tubers, sometimes speckled with white areas near eyes. Flesh is yellowish. Leaves have wide, large leaflets, weakly dissected. Formula is often 4/2, 0,2! - 4,2! basiscopic even by unijugate primary leaflets.
Pedicels below articulation are up to 20 mm long, above articulation 7-9 m long and green, strongly extended to the top with 2/64 up to 5/64 inches, coloured articulation, sometimes clearly defined, short, dense, straight pubescence.
Calyx is medium-sized, about 6-7 mm inside and 7-8 mm outside, green, coroured at the basis, symmetric or bilabiate, mucronules are narrow, appressed or reflected, from one-fourth until one-third of the calyx length.
Corolla is purple-blue, large, with radius about 16-19 mm, lobes are large (about 8-10 mm long), acumen is medium-sized (about 3 mm). Sometimes external doubleness is present.
Anthers are small, about 5,5-6 mm, sometimes underdeveloped and with inside outgrowths, in a displaced conic column. Filaments are straight, which creates the cyathiform of calyx. At the bottom the stamen filaments are coloured with anthocyan, they are 3/64 inches thick, 2-2,5 mm long, 2,5-3 mm distant from the margin.
Style is thick, up to 11 mm long, straight, inclined. Stigma is big and high.
Juz. ¹ 1994 under the name "Francesa negra".
It is grown on the Chiloe island in Yutuy. The variety Francesa negra, known in the old collections,  from Haage and Schmidt is probably not identical to the described cultivar, judging by the colour of tubers.