Solanum elaeagnifolium
2n=24, 48. 72 (in Argentina, Scaldaferro et al. 2012)
Native to the Americas, with an amphitropical distribution, occurring in the deserts and dry zones of the northern hemisphere in the southwestern United States and Mexico and in the southern in Argentina and Chile, but widespread and invasive in tropical and subtropical regions worldwide. It is toxic to livestock and very hard to control, as rootstocks less than 1 cm long can regenerate into plants (Invasive Species South Africa 2012). Introduced and invasive in drier habitats in southern (South Africa and Namibia) and northern (Morocco and Egypt) Africa, in South Africa classified as a noxious weed (Henderson 2011; Invasive Species South Africa 2012) and a quarantine pest in northern Africa (OEPP/EPPO 2007); also known from dry areas around the Mediterranean.
Solanum elaeagnifolium is part of a small clade that is sister to the Old World clade of spiny solanums (Leptostemonum; Stern et al. 2011). The Eleaagnifolium clade has two species in each of the amphigtropical areas of S. elaeagnifolium distribution, but the disjunct populations of S. elaeagnifolium are each others' closest relatives (Sarkinen et al. 2013).
Boyd, J. W., D. S. Murray, and R. J. Tyrl. 1984. Silverleaf nightshade, Solanum elaeagnifolium, origin, distribution and relation to man. Econ. Bot. 38: 210-217.
Chittenden, F. J. 1956. History of Curtis’s Botanical Magazine. In Curtis’s Botanical Magazine Index, 252-269. London: Royal Horticultural Society.
Henderson, L. 2011. Invasive berry-producing Solanaceae. SAPIA News 20: 1-5 (July 2011).
Invasive Species South Africa. 2012. Solanum elaeagnifolium – silver leaf nightshade. http://www.invasives.org.za/invasive-species/item/349-silver-leaf-bitter-apple-%7C-solanum-elaeagnifolium.html
Knapp, S. 2007b. Lectotypification of Cavanilles’ names in Solanum (Solanaceae). Anales Jard. Bot. Madrid 64: 195-203.
Organisation Européene pour la Protection des Plantes/ European Plant Protection Organisation (OEPP/EPPO). 2007. Solanum elaeagnifolium. Bulletin OEPP/EPPO Bulletin 37: 236-245.
Särkinen, T., R.G. Olmstead, L. Bohs & S. Knapp. 2013. A phylogenetic framework for evolutionary study of the nightshades (Solanaceae): a dated 1000-tip tree. BMC Evolutionary Biology 13: 212. doi: 10.1186/1471-2148-13-214
Scaldaferro, M., F. Chiarini, Santiñaque, F.F., Bernardello, G. & Moscone E.A. 2012. Geographical pattern and ploidy levels of the weed Solanum elaeagnifolium (Solanaceae) from Argentina. genetic Resources and Crop Evolution 59: 1833-1847.
Stern, S. R., M. de F. Agra, and L. Bohs. 2011. Molecular delimitation of clades within New World species of the ”spiny solanums” (Solanum subgenus Leptostemonum). Taxon 60: 1429-1441.
Local Names. South Africa: Satansbos, Satanskruid (Afrikaans), Silver-leaf bitter apple (English) (Olckers et al. 1999; Henderson 2011).
(taken from a revision of African species - incomplete as to New World ecology)
Solanum elaeagnifolium is native to the New World, and there it has an amphitropical distribution. It has been introduced worldwide and is common in drier areas of Africa; it is a serious pest of pastures where it has been introduced (Boyd et al. 1984; e.g., Australia, http://www.weeds.org.au/cgi-bin/weedident.cgi?tpl=plant.tpl&ibra=all&card=H42, http://www.westernweeds.org/docs/slnupdate-2009.pdf). It spreads by underground stolons and can regenerate from very small pieces of rootstock (Invasive Species South Africa 2012). In South Africa roots can be as deep as 12 feet in sandy soil (Hattingh s.n.) and only repeated ploughing to a depth of 2 feet will clear the soil (Potgeiter s.n.). In both its native and adventive distribution S. elaeagnifolium is polymorphic for possession of prickles and in Africa both forms occur, even in a single area (e.g., Hattingh s.n., K).
With its stoloniferous habit, narrow leaves and silvery pubescence, S. elaeagnifolium is not easily confused with any other species of Solanum occurring in Africa. The bright orange prickles on prickly morphs might suggest the Madagascan endemic S. pyracanthos, but that species has large purple (rather than small, white or purplish white) flowers and larger leaves. In South Africa, the filiform prickles and prominent leaf venation of some young S. burchellii plants can be reminiscent of S. elaeagnifolium but the prickles of S. burchellii are yellow, its leaves are wider, and its flowers are smaller.
Other narrow leaved African solanums such as S. glabratum and S. sodomaeodes could be confused with S. elaeagnifolium in the herbarium, but neither of these two species is currently sympatric with S. elaeagnifolium. Both S. glabratum and S. sodomaeodes have strongly curved prickles and abaxial leaf trichomes with fewer rays. Solanum lanzae of the black cotton soils of East Africa is also currently not sympatric with S. elaeagnifolium, but has similar narrow leaves and often lacks prickles. Solanum lanzae has larger flowers (9-15 mm in diameter versus 25-40 mm) than does S. eleagnifolium, and has stem trichomes with fewer rays.
The lectotype selected for Ortega’s S. leprosum is a sheet in MA from a plant grown in the Real Jardin Botánico. This may be the same material as was used by Cavanilles to describe S. elaeagnifolium (see Knapp 2007b).
The authorship of the species described in volume 53 of Curtis’s Botanical Magazine (1826) is somewhat problematic (see also S. mammosum with respect to S. platanifolium) Chittenden (1956), in his history of the Magazine, states that in 1826 W.J. Hooker was responsible for the text associated with plates beginning with number 2689 onwards, and from that point he became the editor until his death. In volume 53, plates 2684-2689 have the initials W.H. at the end of the descriptions, but thereafter descriptions are not definitely attributed to Hooker. Despite this, we are certain that Hooker was the author of the description for S. saponaceum; Glasgow is mentioned in the description, and in Hooker’s herbarium at K is the sheet collected by Gillies described in detail in the protologue (“Our dried specimens, in the Herbarium”) bearing a label saying “This seems to be the same species so common all over the province of Mendoza of which the unripe berries are used instead of soap to wash woollens, is called Killo-Killo” We select this sheet (K000546062) as the lectotype and attribute the epithet (a later homonym of S. saponaceum Dunal, 1814) to W.J. Hooker. In the protologue Hooker states that he changed Lindley’s epithet from dealbatum based on the information on Gillie’s collection.
Although read at a Horticultural Society meeting in 1826, Lindley’s description of S. dealbatum did not appear in print until 1830, by which time Hooker’s S. saponaceum was already published. In a footnote, Lindley pointed out that his S. dealbatum was the same as Hooker’s S. saponaceum; since the two descriptions are based on not exactly the same material we are not treating them as homotypic. Lindley cited material sent by a Mr. Place from Chile and a specimen in the Horticultural Society’s herbarium collected by McRae, also from Chile. The Horticultural Society of London’s herbarium was sold in 1856 and is widely dispersed; a sheet at K (K000546063) collected by McRae in Chile and with a “Herb. Hort. Soc. Lond.” is here selected as the lectotype of S. dealbatum.
Solanum texense was described from the first fascicle of Lindheimer’s collections. These were numbered after collection and before distribution from St. Louis, numbers in the protologues refer not to Lindheimer’s collection numbers but to distribution numbers (Blankenship 1907). Care must be taken with these numbers, as the same numbers were given to what were considered the same species in different fascicles. In many herbaria we have seen duplicates of Lindheimer fasc. III 135 labelled as types; these were collected in 1846 and are not type material of S. texense. We have selected the duplicate of Lindheimer fasc. I 135 at MO (MO-3847597) as the lectotype of S. texense; it has Lindheimer’s original label with the collection number “66” on it. We have been unable to locate duplicates of the collection cited in the protologue of S. roemerianum, although a sheet in BM from “Herb. Roemerianum” may be original material.
In the protologue of S. elaeagnifolium var. angustifolium Kuntze cited only “Argentina: San Rafael, Provinz Santiago”, but no specimens. We have selected one of two sheets at NY from the Kuntze herbarium (see Zanoni 1980) as the lectotype (NY00139141); is labelled “San Rafael”. The other possible syntype sheet (NY00139142) is labelled “Santiago” and is probably not a duplicate. Both sheets are annotated by Kuntze.