S. andigenum Juz. et Buk. ssp. tarmense Buk. et Lechn.

S.M. Bukasov. Potatoes of South America and their breeding use, Leningrad, 1933, p. 50

Diagnosis: among varieties of S. andigenum a very stand-alone position is taken by a small group of forms which we separate in an independent sub-species close to S. tenuifilamentum. Its characters are the following.
General habitus among S. andigenum is peculiar due to small, narrow leaflets. Medium leaf dissection. 5 leaflets, in single cases up to 6, more often by the accession , 2-3 out of them of a smaller size. In the most dissected series there are two pairs of primary leaflets, by up to 3, 1 pair of secondary leaflets, one pair of acroscopic leaflets, sometimes they are quite big. (By S. tenuifilamentum dissection is slightly bigger: 6 pairs of leaflets, 3 pairs of primary leaflets in a series, 2 pairs of secondary leaflets, 1 pair of acroscopic leaflets).
By the time of multilayer flowering the peduncle of inflorescence of the 1 order is situated about 3 cm above the stem fork, on the inflorescences above this value is getting less. The upper part of the pedicle is 6-9 mm. Pubescence of pedicle and calyx is very short. Calyx is symmetric 5-6(-8) mm long, acumens are 1-1,5 mm long.
Corolla is small, of a dark-violet shade, like by S. tenuifilamentum, but with less exact star lines. Petals are sloping, narrow, which creates the impression of a bell. Length of corolla radius and width of the lobe basis is 1714 mm (lobe is 9,5 mm long, acumen 4,5 mm). Other measures are 1613, 1714, 2215, 2217 mm.
Stamen filaments are almost straight, this is why the column is slightly conic oval, the length of their free part almost equals to the length of corolla bream (like by S. tenuifilamentum), they are pretty long, thin, thinner than 0,8 mm (almost not thicker than S. tenuifilamentum), colored with anthocyan (like by S. tenuifilamentum). Anthers have a clear vallecula, they are not big, 6-6,5 mm long, 2,5 mm wide.
Style is thin, almost 1/64 dm. (= 450 ). Papillae are about 50 micr. long. Stigma is very small, with a small wide sinus. Ovary us oval. Forms a lot of berries.
Tuberization is more abundant than by the other central Peruvian forms.
Differences from S. tenuifilamentum:
Leaf is less dissected. Peduncle is closer to the stem, its ears are smaller, but they seize the stem more, pigmentation of pedicles and peduncle is stronger. Pubescence of pedicle and calyx by both species is almost undistinguishable, but slightly longer on corolla bud.
Calyx is smaller. Corolla petals are narrower and more sloping. Stamen filaments are not absolutely straight and style is more conic-oval. Anthers are slightly longer and wider at the basis. Style is thinner, stigma is also wide, and ovary is smaller and not conic.
Differences from S. andigenum v. brevicalyx.
Calyx lobes are narrower, 1,75 mm wide (against 2,5 ), calyx basis is narrower, pedicle is thinner, column is oval, style is shorter.
Cultivated in the region Tarma and Huancayo.
Juz. 179, 191b, 602b, seedling 15 from 610 - from Huancayo, accession from Tarma (315b) without number (apparently, Tarma has a more intense violet shade than Tarma , by the stem is more intensely colored and lobes are narrower) and others.
Indigenous name: Tapu.
Ssp. tarmense, except the type has also varieties: with bright corolla and with thin style (which is closer to the type).