Solanum bulbocastanum

Solanum bulbocastanum is one of the most distinctive wild potato species from North and Central America, easily distinguished by its simple leaves and cream to light yellow corollas. It would be hard to confuse with another species except possibly the simple-leaved species with white corollas S. clarum and S. morelliforme that are much smaller plants (stems 2-3 mm wide at base, generally under 0.5 m tall; vs. S. bulbocastanum with stems 3-6 mm wide at base, plants up to 1 m tall).

Correll (1962) designated S. ×michoacanum as a valid nothospecies originating from a cross of S. bulbocastanum and S. pinnatisectum. It is somewhat morphologically intermediate between them but has lateral leaflets and S. bulbocastanum has none.

Dunal (1814) based S. bulbocastanum on the watercolor prepared in the field during the Royal Expedition to New Spain (plate 7 of Spooner et al. 2004) and a copy made by Node-Verán in Montpellier (plate 8 of Spooner et al. 2004). As outlined by D’Arcy (1979), Dean (1997), Nee (1982), and McVaugh (2000) the Royal Expedition to New Spain occurred from 1787 to 1803, and covered Mexico and parts of the Americas. The botanical specimens, manuscripts, and drawings from the expedition initially went to Spain, and Mociño later took them to France in 1812 because of political instability. In Montpellier Moçiño met A. P. de Candolle and M. F. Dunal, the latter who was revising the genus Solanum. DeCandolle left Montpellier for Geneva in 1816 and with Mociño’s permission took most of the watercolor drawings and specimens with him, but seems to have left the Solanum plates with Dunal in Montpellier. Mociño eventually returned to Spain with the original drawings, which were considered lost until they were discovered in 1980 in Barcelona in a private library and purchased by the Hunt Institute for Botanical Documentation in Pittsburgh. The association of one of the original watercolors from the expedition with the Node-Verán black-and-white copy drawing "Tab. 31" cited by Dunal was first made by Spooner et al. (2004) with the kind help of Dr. Robert Kiger at the Hunt Institute for Botanical Documentation.

The holotype of Solanum symphysicaulis has no locality other than Mexico. A specimen at BM appears to be from the same collection and has the same label as the holotype, with a notation that it is from Pavón’s herbarium, and Spooner et al. (2004) considered it as an isotype.

Bitter cited a single collection from W as the type of Solanum bulbocastanum var. latifrons, but there are three specimens with the same label data. Spooner et al. (2004) considered W-125669 as the holotype, because it is the only specimen annotated by Bitter.

Correll (1952) based S. bulbocastanum var. glabrum on non-flowering but fruiting specimens of D. S. Correll 14226, collected in nature on 31 Oct 1947 (NA) and on cultivated plants (D. S. Correll, 14226a) grown at Sturgeon Bay, Wisconsin, fall 1949, from seeds of this collection. The holotype is clearly labeled by Correll. Other herbarium specimens bearing this collection number, grown from seeds, apparently were made later (e.g., PTIS [Correll neg. 64: GH!, UC!]); Spooner et al. (2004) did not consider these as type material.

Three herbarium specimens of S. bulbocastanum were so far out of their typical range as to appear mislabeled, and they clearly were. Two of the specimens were from northern Colombia (Frère Apollinaire s.n., dated Sep 1908 [E], and Frère Idinoël s.n., dated Aug 1909 [G]); and one was from the United States: New Mexico (G. L. Fischer s.n., dated Aug 1912 [G]). These clearly are the same class of falsified collections described by Standley (1927) and attributed mostly to Brother G. Arsène, as they bear a printed label with a black border and bearing script additions, sometimes with two collectors listed and one of them crossed out. Spooner et al. (2004) also encountered one set of these mislabeled Arsène specimens from Mexico that are not listed here under Specimens Examined: Punguato, vicinity of Morelia, 2100 m, 16 Jul 1909, Arsène 2893 (F, G, GH, MEXU, MO, MPU, P, US).