S.M. Bukasov. Potatoes of South America and their breeding use, Leningrad, 1933, p. 60.

Diagnosis: Tubers are long, narrowing down, usually with very little eyes, smetimes dory, black-violet, coloured under skin.
Stem is weakly coloured, decumbent. Leaves are 4-6 paired, with 1-3 pairs of primary leaflets in a series, the upper one is basiscopic, sometimes there is 1 pair of acroscopic.
Pedicle below articulation is 10 (to 24) mm long, above articulation (4) 7-8 mm, articulation is colored, pubescence is outstanding. There are about five flowers in each of the two bostryx of an inflorescence.
Calyx is 8-10 (-12) mm long, sometimes asymmetric ("bilabiate"), calyx lobes do not expand to the top, medium nerve is colored; acumens 1/4-1/3 of calyx length, turned-up.
Corolla is not big, radius about 14 (-17) mm, width of lobe basis is about 16 mm, length of lobe is about 10 mm (consequently, more than half of the corolla radius), length of acumen is about 4 mm, color is dark-violet, star is dark at the beginning.
Stamen filaments are sometimes with pubescence (Pigulevskiy), pretty long, not thick, about 1 mm thick. Anthers are light-yellow, from 6 to 7,25-8 mm long (more often 6,5-7 mm), in an almost straight tightly pressed column, with a heart-shaped basis.
Style is 9,5-10-11 mm long, slightly overtopping the stems, in the lower part covered with papillae. Stigma is big, low, capitate, slightly bipartite, outstanding margin, deep, narrow, sometimes linear sinus. Ovary is egg-like. Forms berries.
Cultivated in department Cuzco: Ccasa cunca (Juz №1235), Omasbamba (Juz. № 1255), Sihua (Juz. №1258), Yana machai (Juz. № 1280, 1283), Ckeccayoc (Juz. № 1361), Cachimayo (Juz. №1403), Patabamba (Juz. №1406); in the region Urubamba: Ollamtaytambo (Juz. №1048, 1079), Rayancancha (Juz. №1058), in Paucartambo (Juz. №827, 1136).
This form is very widely spread in South Peru, more often familiar under the name Beruntun or Berundus, rarer Ocke-lomo, Ocke suittu, Yana lomo, Ccomarancho,  Yana suittu, Yurac nahui, Yana macctachy, Ccusi.
The name of the variety has been given in honor of professor of botanics Cuzco Herrera, who was the first to describe the Peruvian potatoes.
In sexual progeny by Beruntun (№ 827, 1361, 1283) the following characters are constant: in general a not very long pedicle (but for single exceptions), corolla shape, striate character of its color and its blue-violet shade (only its intensity varies), shape of anthers and stigma. Colored articulation dominates.
The following characters vary: outstanding of pubescence (stick out pubescence dominates, like by the type), bent mucronules, size of corolla acumen, thickness of anther stamen filaments (until thick), conic anther column, size of anthers and style.
Sexual progeny by Beruntun varies weakly and does not enter other varieties. An abrupt curve of the lobe and its big length are constant (rarely smaller). Corolla color varies only in intensity until white color (which is very rarely). There are no red shades.