Solanum demissum

Solanum demissum is generally easily distinguished by its high pedicel articulation (in the distal ¼ of the pedicel) and inflorescences in the proximal ½ of the plant, but it can be confused with poorly pressed specimens of S. verrucosum (distinguished by its inrolled corolla margins) and S. stoloniferum (that like S. verrucosum has pedicel articulation below the distal ¼ of the pedicel). It frequently, but not consistently, has a semi-rosette habit seen elsewhere in the wild potatoes in North and Central America only in S. guerreroense.

The collection Galeotti 1175 is a mixed gathering. Only one sheet of two at BR is S. demissum, which Spooner et al. (2004) chose as the lectotype of S. stoloniferum var. pumilum.

Klotzsch (1849) based Solanum utile on plants he grew from seeds received in May of 1849 from Friedrich Otto, Director of the Berlin Botanic Garden. The seeds originally were distributed to the “Gessellschaft der Gartenfreunde Berlin’s” by the “Landes-Oekonomie-Collegium” for the purpose of cultivation and experimentation. The Klotzsch specimens at Berlin were destroyed; the neotype of Spooner et al. (2004) dates from 1852 and was part of Klotzsch's herbarium. Two other specimens at UPS from Klotzsch's herbarium are dated 1855. The neotype bears Bitter’s annotation “Solanum demissum var. klotzchii,” a name never published.

Rybin (1929) indicated S. demissum f. xitlense had conical fruits, but the type specimen lacks mature fruits. The high-placed pedicel articulation and enlarged terminal leaflets clearly show it to be S. demissum.

Solanum semidemissum Juz. ex Bukasov was first mentioned in Trudy Prikl. Bot. 47: 60, 480 (1930). Page 60 is the Russian text, and page 480 is its English translation, but there is no description. Juzepczuk (1937) validated the name and cited M. Antipovich 25 and M. Antopovich 28. WIR loaned Spooner et al. (2004) three sheets of Antipovich 25, and one flowering specimen of M. Antipovich 28, which these authors designated the latter as lectotype as it was the most complete specimen.

Juzepczuk (1937) and Hawkes (1990) recognized S. semidemissum as a pentaploid nothospecies, formed by hybridization between S. demissum and S. verrucosum, distributed in the state of México and the Federal District. Pentaploid populations (2n = 5x = 60) similar to these species have been identified as S. semidemissum (Rybin 1933; Juzepczuk 1937; Hawkes 1944), supporting a hybrid origin, but Spooner et al. (2004) could not find any characters to give them even a hint of traits with which to distinguish these hybrids. Solanum semidemissum possibly is a hybrid taxon, which bears further investigation with field study. Spooner et al. (2004) provided the herbarium annotations Hawkes made for S. semidemissum to aid others to pursue this further, but cite them in their treatment as S. demissum: Antipovich 25; Balls et al. 5046; Flores S-696; Hawkes et al. 1597; Hawkes et al. 1675, 2501, 2502, 2503; Lyonnet 2147; Martínez s.n.; Tarn 78; Tarn & Flores 72, 79; Ugent et al. 1188.

Hawkes (1944) listed syntypes for the following three names for which Spooner et al. (2004) designated lectotypes. For S. demissum var. mastoidostigma he cited Balls et al. 4242, Balls et al. 4246 (the lectotype) and Balls et al. 5009; material of Balls et al. 4242 was not located. He based S. demissum var. orientale on Balls et al. 4441 (the lectotype), Balls et al. (4621a, and Balls et al. 5305. For S. demissum var. demissum f. tolucense he listed Balls et al. 4971 and Balls et al. 4971/2 (the lectotype), both from the same locality but the second collection at 11,000 ft. and dated three days later.

Solanum ×edinense is of clear hybrid origin between S. demissum and the cultivated species S. tuberosum. It can be distinguished from S. demissum by its generally wider leaves and taller stature, and from S. tuberosum by its high-placedpedicel articulation. It differs from both its parents by its pentaploidy.