S. andigenum Juz. et Buk. var. sihuanum Buk. et Lechn.

S.M. Bukasov. Potatoes of South America and their breeding use, Leningrad, 1933, p. 58.

Diagnosis: Tubers are yellow, long.
Plants are high, after efflorescence not strongly decumbent. Leaves are with relative wide leaflets, 5-paired, 2-3 pairs of secondary leaflets in a series, upper leaflet is basiscopic.
Pedicle above articulation is long. Calyx has deflected acumens. Corolla is light-blue with big petals.
Stamen filaments are long, 3 mm long, overtop corolla margin for 2 mm , 1 mm thick at the bottom, 2/64 dm. at the top, with aging they are straight, yellow. Anthers are at first in a slightly conic, than in an almost straight column. Berries are elongate.
Cultivated in dep. Cuzco: Ccumara (Juz. 1241), Sihua (Juz. 1260, 1261), Omasbamba (Juz. 1256), Chinchero (Juz. 1418), Paucartambo (Juz. 1468, 1261).
Indigenous names: huacacc-caillon, ppispinco, huamara, mauchcha sencca, misquilla de saucant.
In sexual progeny 1261 calyx symmetry and long anther filaments remain constant.
The following characters dominate: long upper and lower parts of pedicle and position of articulation at the hight of two-thirds of pedicle. Uncolored articulations, strongly tapered mucronules (single are appressed) and their length and width. Corolla is strongly splitted which is characteristic for the type. Absence of dark corolla. Thin stamen filaments (there are also thicker), narrow anthers with sinuate basis, like by the type, slightly conic ("straight") column, style thickness.
Varies without any clear domination: thickness of pedicle, length and dense of its pubescence (to a strong extent), length of upper and lower part of pedicle and compactness of inflorescence, shape of calyx lobes (sometimes expanding to the top), calyx basis, sometimes of the type S. goniocalyx, size of corolla and its acumens, corolla color (light-blue, like by the type, dark-violet, light-violet, white1), shape of stigma (to a strong extent), length of style (from slightly overtopping the anthers until long, 14 mm).
Dissection by 1418 is of the same character, allowing the possibility of hybridization with distant forms.

1) Appearing in the progeny of this variation with a low intensity of anthocyan color of corolla by white flowered accessions should be noticed, which apparently has not been noticed (or if, than rarely) by intensively colored forms.