S. andigenum Juz. et Buk. var. mexicanum Buk.f. tolucanum Buk.

S.M. Bukasov. Potatoes of South America and their breeding use, Leningrad, 1933, p. 76

Diagnosis: Small calyx, internal length 7-8 mm, small apex, about 1/4 of calyx length, 2 mm long, corolla lobes are small, their length takes about 1/3 of the corolla radius, abruptly erose by the commissure, corolla acumens are bigger, about 3-4 mm, anthers are perfect; berries are present.
Tubers are on long stolons with stems, scattered color distribution, from dark-pink to red, darker in the eyes, round. Stems are ramified. Leaves are small, about 11 cm long, stalk 2 cm, with small leaflets (size of the terminal leaflet is 3018 mm, first lateral leaflet 3016), 4-5 pairs, 2-3 out of them are small; there are usually 2 pairs of intermediate primary leaflets in a series, sometimes they are up to 3 with one pair of secondary leaflets (until the first series), in the end series there is one pair of secondary leaflets.
Inflorescence with small apex leaves. Pedicel below articulation is about 22 mm long, above - about 6 mm, often the articulation takes 2/3 of pedicel length, pubescence is dense, short, adpressed, like on the calyx lobes.
Pedicel goes almost opposite to the stem leaf, slightly lower than it (0,5 cm lower). Flower-bearing leaf is 2-3,5 cm above the divergence of the flower stalk. Auricles of the flower stalk are 11mm long. Dissection of the flower-bearing leaf: 3-4 pairs of leaflets (out of them 1-2 smaller), no primary leaflets in the end series, the rest two have 1 couple each. Axillary stem under the flower stalk is only a little bit weaker than the main stem. Multi-tire flowering.
Calyx is with anthocyan in the nerve, up to 10 mm long, external acumens are sometimes very short, up to 1/6 of calyx length, weakly reflected. Corolla bud is narrow with a conic apex. Corolla is small, with a radius 15-16 mm, with a dark star (on young flowers) above, dark-green-purple from the top, purple from the bottom, corolla is completely lilac, sometimes with small white tips down, on the top they occur seldom.
Corolla tube below origin from stems is pretty long (3-3,5 mm), longer than the filaments (1,5-2 mm). Stamen filaments are not yellow, thin (900) 1000-1100 (1200) micr., thinner than by the most selection cultivars.
Anthers are 5,5-6,5 mm long, densely closed in a slightly conic column, on old flowers one anther exserts upwards. Style is inclined, slim, 450-510 , strongly excerting the stems, more than to one half covered with papillae. Stigma is small, short, slightly flattened, with a big sinus.
Sexual progeny from naturally formed seeds is rather homogeneous and similar to the parent form in calyx shape, shape and color of corolla and star, form of anthers.
The size of leaf and leaflets varies (sometimes a little), length of upper and lower part of pedicel and kind of pubescence, calyx length up to 11 mm, apexes up to 1/3 of calyx length, intensity of pedicel and corolla color, anther size from 6 to 8 mm, anther shape, columns, style length and size of stigma. Splitting is very weak and varying characters dont get outside of the scope of the described form.
Geographic distribution: Mexico, state Mexico: Toluca, Cuahutzingo, San Andres; 1,2,5,7 (collected by the author) and the accession from San Andres, collected by .S. Antipovich.