Solanum berthaultii

Citation author:

J. G. Hawkes

Citation:

Bull. Imp. Bur. Pl. Breed. Genet., Cambridge. 45, 122, Figure 32. 1944.

Type:

Bolivia. Cochabamba: vicinity of Cochabamba, SE of city, Cerro de San Pedro, 8500 ft, 18 Mar 1939, E.K. Balls, W.B. Gourlay & J.G. Hawkes 6297 (lectotype, K, designated by Hawkes & Hjerting, 1989; isolectotypes, BM000565905 [Correll neg. 907, BM, F-1603012, LL, MO-5588720, NY, PTIS, UC-1152177], C, CPC [Correll neg. 759, F-1603121, LL, NY, UC-1152177], K-8 sheets [Correll neg. 56, F-1604854, LL, NY, UC-1152178; Correll neg. 758, F-1603031, LL, NY, UC-1152177], UC683654 [Correll neg. 757, F-1603030, LL, NY, UC-1152177], UC-683655, US00027476 [Correll neg. 760, F-1603122, LL, UC-1152178, NY, PTIS, UC-1152178], US00027475).

Last edited by:

Spooner, D.M.

Written by:

Spooner, D.M. & D. Fajardo

Habit:

Herbs 0.3-1 m tall, erect. Stems 3-5 mm in diameter at base of plant, unwinged or with wings to 1 mm wide, densely pubescent with short non-glandular trichomes and short glandular trichomes, 120-210 μm in length, with tetralobulate heads, 50-70 μm in diameter, and often with longer glandular trichomes, 600-950 μm in length, with an ovoid gland at the tip, 20-60 μm in diameter, yellowish to light green.

Sympodial structure:

Sympodial units tri- to plurifoliate, not geminate.

Leaves:

Leaves odd-pinnate, the blades 10-28 x 6-20 cm, varying greatly in shape and size, yellowish to light green, membranous to chartaceous, moderately pubescent adaxially and abaxially, with hairs like those of the stems; lateral leaflet pairs 3-6, often subequal except for the most proximal 1 or 2 pairs that are greatly reduced in size; most distal lateral leaflets 2-7.5 x 1-4.5 cm, narrowly to broadly ovate, the apex acuminate, the base typically oblique, cordate to rounded, subsessile or with petiolules up to 10 mm long; terminal leaflet 3-12 x 1.5-4 cm, ovate to elliptic, the apex acute to acuminate, the base attenuate; interjected leaflets 0-25, sessile to short petiolulate, ovate to orbicular; petioles 0.5-4.5 cm, pubescent as the stem. Pseudostipules 5-17 mm long, lunate, pubescent with hairs like those of the stem.

Inflorescences:

Inflorescences 5-15 cm, terminal with a subtending axillary bud, generally in distal half of the plant, usually forked, with 5-15 flowers, with all flowers apparently perfect, the axes pubescent with hairs like those of the stem; peduncle 3-9.5 cm long; pedicels 12-22 mm long in flower and fruit, spaced 1-10 mm apart, typically articulated in the distal half.

Flowers:

Flowers homostylous, 5-merous. Calyx 5-15 mm long, the tube 1-2 mm, the lobes 4-8 mm, long attenuate, the acumens 1-3 mm long, with hairs like those of the stem. Corolla 1.1-2.5 cm in diameter, substellate to pentagonal, pure white to rarely creamy white or faintly yellowish to medium blue to dark blue to lilac above and below, the tube 1-2 mm long, the acumens 1-3 mm long, the corolla edges flat, not folded dorsally, glabrous abaxially, minutely puberulent adaxially, especially along the midribs, ciliate at the margins, especially at the tips of the lobes. Stamens with the filaments 1-2 mm long; anthers 5-9 mm long, lanceolate, connivent, yellow, poricidal at the tips, the pores lengthening to slits with age. Ovary glabrous; style 11-14 mm x ca. 1 mm, exceeding stamens by 2-5 mm, straight, glabrous; stigma clavate to capitate.

Fruits:

Fruit a globose to slightly ovoid berry, 1.5-2.5 cm in diameter, medium to deep green when ripe, often with scattered white dots, glabrous.

Seeds:

Seeds from living specimens ovoid and ca. 2 mm long, whitish to greenish in fresh condition and drying brownish, with a thick covering of “hair-like” lateral walls of the testal cells that make the seeds mucilaginous when wet, green-white throughout; testal cells honeycomb-shaped when lateral walls removed by enzyme digestion.

Chromosome number:

2n = 2x = 24 voucher: Ochoa & Salas 15565 (US) (Hijmans, et al. 2007)

Distribution:

Western Bolivia (Dept. La Paz), south to northern Argentina (Provs. Catamarca, Jujuy and Salta), in generally dry rocky areas in the open or among spiny shrubs or cacti, along streamsides, or a weed at the edges of cultivated fields or roadsides, (1200) 1600-2100 (3950) m.

Phenology:

Flowering and fruiting from January to March.

Phylogeny:

Solanum berthaultii is a member of Solanum sect. Petota Dumort., the tuber-bearing cultivated and wild potatoes. On a higher taxonomic level, it is a member of the informally-named Potato Clade, a group of perhaps 200-300 species that also includes the tomato and its wild relatives (Bohs, 2005).

Commentary:

Hawkes (1963) and Hawkes & Hjerting (1989) treated S. berthaultii as a hybrid species between S. tarijense and "a blue-flowered mountain species, possibly S. sparsipilum." Hawkes & Hjerting (1989) subsequently reversed their opinion regarding the hybrid origin of S. berthaultii, but continued to hypothesize extensive hybridization between S. berthaultii and S. tarijense. Fifteen percent of the S. berthaultii and S. tarijense accessions listed in Hanneman & Bamberg (1986) and 24% of the specimens cited in Hawkes & Hjerting (1989) are listed as natural interspecific S. berthaultii x S. tarijense hybrids. Further mention of these here will be "hybrids" for simplicity.

Until 2007 (Spooner et al., 2007) Solanum berthaultii and S. tarijense were recognized as distinct species, since their original description by Hawkes in 1944. A morphological study of Spooner & van den Berg (1992) questioned the validity of separate species status for S. berthaultii and S. tarijense. Multivariate analyses of morphological data failed to support separate species, showing great overlap of three “species-specific” characters used to separate the species (presence/absence Type B trichomes [long-stalked glandular trichomes], corolla color, corolla shape), and a geographic analysis of these characters showed them to be distributed throughout the range of both species. For example, intra-accession variability for presence/absence of Type B trichomes was encountered in eight of the 64 accessions examined. Corolla colors varied continuously from pure white to dark-blue, and plants from only one geographic area in the extreme south of Salta Province had all corollas pure white (a S. tarijense character, but most of these accessions possessed Type B trichomes, a S. berthaultii character). Corolla colors and shapes exhibited no statistically significant differences between any of the taxa.

Hawkes & Hjerting (1989) designated K as the deposition of the holotype of S. berthaultii, but we did not find a sheet designated as holotype despite our extensive searches there.

The locality of Solanum vallegrandense is a correction provided in Hawkes & Hjerting, 1989: 144, 258, by pers. comm. from M. Cárdenas, of erroneous locality data originally reported on specimens and in the protologue, reported as “on way from Trigal to Mataral, 2000 m.”

Many collections of Hawkes and his collaborators were deposited at the Commonwealth Potato Collection (CPC) herbarium in Dundee Scotland, and Correll took many photos of these. All of these collections were widely distributed to other herbaria but we were not able to locate all of the specimens that match the photos.

References:

Hawkes, J.G. 1963. A revision of the tuber-bearing Solanums. II.
Scott. Pl. Breed. Sta. Rec. 1963: 76-181.

Hawkes, J.G. & J.P. Hjerting 1969. The potatoes of Argentina, Brazil, Paraguay and Uruguay: a biosystematic study.
Oxford Univ. Press, Oxford, UK.

Hanneman, R.E. & J.B. Bamberg 1986. Inventory of the tuber-bearing Solanum species.
Wisconsin Agric Exp. Sta. Bull. 533: 1-216.

Hawkes, J.G. & J.P. Hjerting 1989. The potatoes of Bolivia: their breeding value and evolutionary relationships.
Oxford University Press, Oxford.

Hawkes, J.G. 1990. The potato: evolution, biodiversity and genetic resources.
Oxford: Belhaven Press.

Spooner, D.M. & R.G. van den Berg 1992. Species limits and hypotheses of hybridization of Solanum berthaultii Hawkes and S. tarijense Hawkes: morphological data.
Taxon 41: 685-700.

Bohs, L. 2005. Major clades in Solanum based on ndhF sequences.
Pp. 27-49 in R. C. Keating, V. C. Hollowell, & T. B. Croat (eds.), A festschrift for William G. D’Arcy: the legacy of a taxonomist. Monographs in Systematic Botany from the Missouri Botanical Garden, Vol. 104. Missouri Botanical Garden Press, St. Louis.

Spooner, D.M., D. Fajardo, & G.J. Bryan 2007. Species limits of Solanum berthaultii Hawkes and S. tarijense Hawkes and the implications for species boundaries in Solanum sect. Petota.
Taxon 56: 987-999.

Hijmans, R., T. Gavrilenko, S. Stephenson, J. Bamberg, A. Salas & D.M. Spooner 2007. Geographic and environmental range expansion through polyploidy in wild potatoes (Solanum section Petota).
Global Ecol. Biogeogr. 16: 485-495.

Taxonomic name:

Solanum berthaultii (Solanaceae)

Solanaceae Source

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Solanum berthaultii

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