Solanum tweedieanum Hook., Bot. Mag. 62: tab. 3385. 1835, as "Tweedianum" .

Knapp, Sandra, Saerkinen, Tiina & Barboza, Gloria E., 2023, A revision of the South American species of the Morelloid clade (Solanum L., Solanaceae), PhytoKeys 231, pp. 1-342 : 1

59. Solanum tweedieanum Hook., Bot. Mag. 62: tab. 3385. 1835, as "Tweedianum".

Figs 178 , 179

Solanum atriplicifolium Gillies ex Nees, Nov. Act. Acad. Caes. Leop. 19, Suppl. 1: 386. 1843. Type. Argentina. Mendoza: El Diamante, [no date], J. Gillies s.n. (lectotype, designated by Barboza et al. 2013, pg. 239): E [E00112916]; isolectotypes: E [E00057545], K[K000585737], NY [00139057]).

Solanum nigrum L. subsp. atriplicifolium (Gillies ex Nees) Sendtn., Fl. Bras. (Martius) 10: 17. 1846. Type. Based on S. atriplicifolium Gillies ex Nees.

Solanum haarupii Bitter, Repert. Spec. Nov. Regni Veg. 11: 210. 1912. Type. Argentina. Mendoza: Estancia Santa Rosa, 1904, A.C. Jensen-Haarup s.n. (holotype: UPS; isotype: US [00027594, acc. # 1081085]).

Solanum meizonanthum Bitter, Repert. Spec. Nov. Regni Veg. 11: 214. 1912. Type. Argentina. Entre Ríos: Paraná, 16 Aug 1892, G. Niederlein 270 (holotype: B, destroyed [F neg. 2783]; lectotype, designated by Knapp et al. 2020, pg. 40: F [V0361924F, acc. # 621142]).

Solanum atriplicoides Herter, Rev. Sudamer. Bot. 7: 226. 1943, nom. illeg. superfl. Type. Based on Solanum atriplicifolium Gillies ex Nees.

Type.

Cultivated [Glasgow Botanical Garden, protologue] from seeds sent by J. Tweedie from "near Buenos Ayres", Anon. s.n. (lectotype, designated by Edmonds 1972, pg. 102 [as “holotype”], second step designated by Knapp et al. 2020, pg. 40: K [K000585739]; isolectotype: K [K000585738]).

Description.

Perennial herbs or subshrubs woody at the base, rhizomatous, 0.1-0.75 m high, viscid to the touch, the branches erect to spreading. Stems terete, densely pubescent with glandular transparent simple uniseriate trichomes mostly 0.5 mm long and 1-2-celled, but some scattered trichomes 6-10-celled, 1-1.5 mm long, the glandular tips unicellular; new growth viscid-pubescent with glandular simple uniseriate trichomes like those of the stems; bark of older stems pale tan, the longer trichomes deciduous, but stems remaining viscid with shorter glandular trichomes. Sympodial units difoliate, the leaves not geminate, but occasionally arising very near each other. Leaves simple and usually shallowly toothed, the blades (1.5)4-6 cm long, (0.8)2-5 cm wide, ovate to elliptic, widest at or just below the middle, membranous, concolorous, viscid to touch, extremely variable in size both between and within plants; adaxial surfaces evenly and more or less densely pubescent on the veins and lamina with transparent glandular simple uniseriate trichomes 0.2-0.5(-1) mm long; abaxial surfaces similarly viscid-pubescent, the glandular trichomes denser along the veins; principal veins (4)4-7 pairs, sometimes drying yellowish; base truncate, then slightly decurrent along the petiole as a wing less than 0.5 mm wide; margins usually shallowly toothed, occasionally almost entire, the teeth to 2.5 mm long, broadly deltate with acute to slightly rounded apices, the sinuses reaching less than 1/4 of the way to the midrib; apex acute; petiole 0.5-2.5 cm long, with a narrow wing of leaf tissue along most of its length. Inflorescences opposite the leaves, usually unbranched (forked in Wood et al. 18764 from Bolivia), 1.5-6 cm long, with 4-8 flowers clustered in the distal portion, densely glandular pubescent with transparent, simple uniseriate trichomes to 1 mm long; peduncle 1-4 cm long; pedicels 0.7-1 cm long, ca. 0.5 mm in diameter at the base, gradually tapering to an apex ca. 1 mm in diameter, nodding or somewhat spreading at anthesis, densely glandular pubescent like the rest of the inflorescence, articulated at the base; pedicel scars clustered at the tips of the inflorescence 1-2 mm apart. Buds ellipsoid, the calyx ca. halfway exserted from the tips of the calyx lobes before anthesis. Flowers 5-merous, cosexual (hermaphroditic). Calyx tube (0.5)1-1.5 mm long, cup-shaped to somewhat urceolate, the lobes 3.5-5 mm long, 2-3 mm wide, narrowly triangular with pointed tips, densely glandular pubescent with transparent simple uniseriate trichomes. Corolla 1.2-1.6 cm in diameter, white or lavender with a pale greenish yellow central eye, stellate, lobed ca. 2/3 of the way to the base, the lobes 4-5 mm long, 3-5 mm wide, triangular, spreading or reflexed at anthesis, glabrous adaxially, densely glandular-papillate abaxially especially along the midvein and at lobe tips, with a few longer glandular simple uniseriate trichomes at the lobe tips. Stamens equal, or sometimes the lowermost apparently very slightly longer; filament tube minute; free portion of the filaments 0.5-1 mm long, slightly unequal, glabrous or sparsely pubescent adaxially with eglandular tangled simple uniseriate trichomes; anthers (3.6)4-5(6) cm long, 1-1.2 mm wide, ellipsoid, yellow, poricidal at the tips, the pores lengthening to slits with age. Ovary conical, glabrous; style ca. 9 mm long, slightly curved upwards, exserted beyond the anther cone, densely pubescent in the lower third with 2-3-celled simple uniseriate trichomes to 0.5 mm long; stigma large-capitate to somewhat bilobed, yellow-green in live plants, the surface minutely papillate. Fruit a globose berry, 0.4-0.8 cm in diameter, greenish white to cream at maturity, tightly enclosed in the accrescent calyx, the pericarp thin, matte, opaque, glabrous; fruiting pedicels 0.8-1.1 cm long, ca. 0.75 mm in diameter at the base, ca. 1.1 mm in diameter at the apex, nodding, strongly deflexed at the base with a distinct bend, not markedly woody, not persistent; fruiting calyx accrescent and tightly investing the berry, the tube 3-3.5 mm long, the lobes 2.5-8 mm long, the lobes expanding more than the tube, remaining viscid-pubescent. Seeds 10-20 per berry, ca. 2 mm long, ca. 1.5 mm wide, flattened and teardrop shaped, pale tan to reddish brown, the surfaces minutely pitted, the testal cells sinuate in outline. Stone cells 8-10 per berry, 2 apical (fide Bitter 1914a), to 1.2 mm in diameter, the rest scattered through the mesocarp, 0.7-1 mm in diameter, all creamy white. Chromosome number: n = 12 ( Moscone 1992, vouchers Del Vitto & Moscone 854, Di Fulvio 783, Hunziker 24883, 25036, all as S. atriplicifolium ).

Distribution

(Fig. 180 ). Solanum tweedieanum occurs on the eastern Andean slopes and foothills and into the littoral (Argentina) in Bolivia (Depts. Santa Cruz, Tarija), Paraguay (Depts. Boquerón, Central), and across Argentina (Provs. Buenos Aires, Catamarca, Córdoba, Entre Ríos, Formosa, Jujuy, La Pampa, La Rioja, Mendoza, Río Negro, Salta, San Juan, San Luis, Santiago del Estero, Tucumán).

Ecology and habitat.

Solanum tweedieanum grows in a very wide range of habitats from the littoral of Argentina, Chaco woodlands and high elevation open areas above tree line in the Andes, from near sea level to 3,500 m elevation. It often is found in the shade of trees in loose soil or in the cracks of rocks, often in large patches connected with underground rhizomes.

Common names and uses.

None recorded.

Preliminary conservation status

( IUCN 2022). Least Concern [LC]. EOO = 2,010,678 km2 [LC]; AOO = 1,420 km2 [VU]. Solanum tweedieanum is a widespread species that reproduces clonally by rhizomes and occupies a wide range of habitats. It is found within protected areas in a variety of habitats in Argentina (e.g., Pampa de Achala, Ernesto Tornquist Provincial Park) and probably also occurs in the Paraguayan Parque Nacional Defensores del Chaco.

Discussion.

Solanum tweedieanum is one of the mostly widely distributed of the glandular-pubescent morelloid species with accrescent calyces in fruit. The name S. atriplicifolium was formerly applied to this species (e.g., Barboza et al. 2013) but re-evaluation of taxon circumscription and types revealed that the names for glandular-haired species with accrescent calyces were previously incorrectly applied ( Knapp et al. 2020). Previously Barboza et al. (2013) recognised S. "tweedianum " Hook. (a mis-spelling of S. tweedieanum , see below) and S. atriplicifolium as distinct species and placed S. physalidicalyx in synonymy with S. tweedieanum . The type of S. tweedieanum does not match these specimens but is a better match for the plants called S. atriplicifolium in Barboza et al. (2013). The type of S. tweedieanum comes from a plant cultivated at Kew that was collected in flower only; it lacks the diagnostic calyx characters (see fig. 1 in Knapp et al. 2020) that enable easy identification in this group, but anther length can also be used to distinguish those plants not in fruit. Plants with inflated calyces have shorter anthers than do those with calyces that are merely accrescent and tightly investing the berry; the types of both S. tweedieanum and S. atriplicifolium have longer (to 6 mm) anthers and belong to the same species, for which the oldest name is S. tweedieanum .

Solanum tweedieanum is most similar to S. physalidicalyx , from which it differs in having longer anthers (4-6 mm long versus 3-4 mm long in S. physalidicalyx ) and a fruiting calyx that is accrescent but tightly invests the pale cream berry rather than the inflated accrescent calyx of S. physalidicalyx that is somewhat invaginate at the base. In mature fruit, the calyx lobes are longer than the tube in S. tweedieanum , whereas in S. physalidicalyx the inflated tube is longer than the lobes, but this can be difficult to see in herbarium specimens, and in the absence of mature fruit, determination can be difficult.

The chromosome count of 2n = 24 reported by Edmonds (1972) for S. tweedieanum (as Solanum tweedianum ) is based on a voucher (Hawkes et al. 3204) we have been unable to locate. From the locality (between Mina Clavero and Villa Dolores in Córdoba, Argentina), this could represent either S. tweedieanum or S. physalidicalyx .

Details of the orthography of the name and typification of S. tweedieanum and its synonyms are treated in Knapp et al. (2020) as is the confusion over the application of this name.

Figures

Figure 178. Solanum tweedieanum A flowering habit B fruiting habit C detail of adaxial leaf surface D detail of abaxial leaf surface E glandular trichome of the stem F flower bud G dissected flower H maturing fruit (A-D, F, G Wood & Goyder 16818 E voucher details missing). Illustration by R. Wise and V. Dudas. Previously published in part in Cabrera (1983: 404) and Barboza et al. (2013: 239) as S. atriplicifolium.

Figure 179. Solanum tweedieanum A habit B flowering branch C inflorescence with corolla colour variation D flower at anthesis (A Barboza et al. 3483 B Barboza et al. 3472 C Barboza et al. 3486 D Barboza et al. 3474). Photos by S. Knapp.

Figure 180. Distribution map of Solanum tweedieanum.