Solanum triflorum Nutt., Gen. N. Amer. Pl. 1: 128. 1818.

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

57. Solanum triflorum Nutt., Gen. N. Amer. Pl. 1: 128. 1818.

Figs 4I , 172 , 173

Solanum triflorum Nutt. var. majus Hook., Fl. Bor.-Amer. 2: 90. 1837, as " major ". Type. Canada. Saskatchewan: "Carleton House Fort, Saskatchewan River", J. Richardson s.n. (lectotype, designated by Särkinen et al. 2018, pg. 167: BM [BM000934745]; isolectotype: K [K001159656, large plants]).

Solanum triflorum Nutt. var. minus Hook., Fl. Bor.-Amer. 2: 90. 1837, as " minor ". Type. Canada. Saskatchewan: "In the Garden (a weed) of Carleton House Fort, entrance of Badger’s Hole, and Saskatchewan River to Edmonton House" [protologue], T. Drummond s.n. (lectotype, designated by Särkinen et al. 2018, pg. 167: E [E00526685]; isolectotypes: BM [BM000934744], K [K001159656]).

Solanum mendocinum Phil., Anales Univ. Chile 21(2): 403. 1862. Type. Argentina. Mendoza: Mendoza, 1860-1861, W. Díaz s.n. (lectotype, designated by Hunziker 1989, pg. 184 [superfluously by Barboza et al. 2013, pg. 260]: SGO [SGO000004580, acc. # 055499]).

Solanum calophyllum Phil., Anales Univ. Chile 21(2): 403. 1862. Type. Argentina. Mendoza: Mendoza, 1860-1861, R. Philippi s.n. (lectotype, designated by Hunziker 1989, pg. 184 [superfluously by Särkinen et al. 2018, pg. 167; cited as holotype in Barboza et al. 2013]: SGO [SGO000004552]; isolectotype: G [G00343450]).

Solanum pyrethrifolium Griseb., Abh. Königl. Ges. Wiss. Göttingen 24: 250. 1879. Type. Argentina. Tucumán: Lules, Dec 1873, P. G. Lorentz & G. Hieronymus 1132 (lectotype, designated by Morton 1976, pg. 102: CORD [CORD00006111]; isolectotype: GOET [GOET003594]).

Solanum gaudichaudii Dunal var. pyrethrifolium (Griseb.) Kuntze, Revis. Gen. Pl. 3(3): 226. 1898. Type. Based on Solanum pyrethrifolium Griseb.

Solanum triflorum Nutt. var. calophyllum (Phil.) Bitter, Abh. Naturwiss. Vereine Bremen 23: 144. 1914. Type. Based on Solanum calophyllum Phil.

Solanum triflorum Nutt. var. pyrethrifolium (Griseb.) Bitter ex Probst, Mitteil. Naturfor. Gesellsch. Solothurn 9: 41. 1932. Type. Based on Solanum pyrethrifolium Griseb.

Type.

United States of America. North Dakota [McLean County]: Near Fort Mandan , Anon. [Lewis & Clark] s.n. (lectotype, designated by Hunziker 1989, pg. 189 [superfluously by Barboza et al. 2013, pg. 260]: PH [00030496]).

Description.

Annual herbs to 0.4 m high, much branched at the base, to 0.7 m in diameter. Stems terete, green, decumbent and prostrate, forming adventitious roots at the nodes, not markedly hollow; new growth glabrous to sparsely pubescent with eglandular simple, uniseriate (3-)4-10-celled spreading trichomes 0.5-2 mm long, occasionally with a few glandular trichomes with a 1-many-celled apical gland; older stems glabrescent. Sympodial units difoliate or trifoliate, the leaves not geminate. Leaves simple and shallowly lobed to deeply pinnatifid, the blades (1-)2-4(-5) cm long, 0.2-2.9 cm wide, narrowly elliptic to oblong or ovate-elliptic, widest in the lower half, membranous to somewhat fleshy, discolorous; adaxial surface glabrous to sparsely pubescent with simple, uniseriate trichomes like those on stem, scattered along lamina and more densely along the veins; abaxial surface more densely pubescent on veins and lamina; major veins 3-6 pairs, not clearly evident abaxially; base cuneate, decurrent on the petiole; margins almost entire to sinuate-lobate to deeply pinnatifid to near-pinnate, with 3-6 linear to triangular pairs of lobes; apex acute; petioles (0.5-)1-2(-2.4) cm long, pubescent with simple uniseriate trichomes like those of the stems. Inflorescences internodal, unbranched, 1-2 cm long, with 1-5(-6) flowers clustered near the tips (sub-umbelliform), glabrous to sparsely pubescent with spreading trichomes like those of the stems; peduncle 0.8-3.5 cm long, often with apical leafy “bracteoles” (small, leaf-like structures amongst the pedicels); pedicels 3-12 mm long, 0.4-0.5 mm in diameter at the base and 0.4-0.5 mm in diameter at the apex, straight and spreading, articulated at the base; pedicel scars spaced 0(-0.5) mm apart. Buds narrowly ellipsoid or occasionally narrowly ovoid, the corolla exserted 1/5-2/5 from the calyx tube before anthesis. Flowers 5-merous, cosexual (hermaphroditic). Calyx tube 1-1.5 mm long, conical, the lobes 2.5-3.5(-7) mm long, 0.8-1(-4) mm wide, triangular-oblong with acute apices, densely pubescent with simple, uniseriate eglandular trichomes like those of the stem. Corolla 1-1.4 cm in diameter, white to lilac with a yellow-green central eye with black-purple colouration at the base, deeply stellate, lobed halfway to 3/4 of the way to the base, the lobes 4-5 mm long, 1.8-2.2 mm wide, reflexed at anthesis, densely pubescent abaxially with short simple uniseriate eglandular trichomes like those on stems and leaves. Stamens equal; filament tube minute; free portion of the filaments 0.6-1 mm long, adaxially sparsely pubescent with tangled simple, uniseriate trichomes; anthers 2.8-3.1(-4) mm long, 0.4-0.5 mm wide, narrowly ellipsoid, pale yellow, poricidal at the tips, the pores lengthening to slits with age and drying. Ovary globose, glabrous; style 2.5-3.5 mm long, straight, not exserted beyond the anther cone, densely pubescent with 2-3-celled simple uniseriate trichomes to 1/2 from the base; stigma capitate, minutely papillate, green in live plants. Fruit a globose berry, 0.8-1(-2) cm in diameter, dark green at maturity, the pericarp thin, usually shiny, opaque, glabrous; fruiting pedicels 12-17 mm long, 0.5-1 mm in diameter at the base, 1-1.5 mm in diameter at the apex, spaced 0-0.5(-1) mm apart, reflexed and becoming woody, not persistent; fruiting calyx somewhat accrescent in fruit, but not becoming papery nor covering the berry, the tube 2.5-3 mm long, the lobes (4-)4.5-5.5(-8) mm long and 2.2-3.5 mm wide, strongly reflexed to spreading. Seeds 40-60 per berry, 2-2.5 mm long, 1.7-2 mm wide, subglobose, yellow, the surfaces minutely pitted, the testal cells pentagonal in outline. Stone cells 13-30, 1-1.5 mm in diameter, creamy white or pale tan. Chromosome number: n = 12 ( Moyetta et al. 2013, voucher Chiapella et al. 1839).

Distribution

(Fig. 174 ). Solanum triflorum is native to the Americas with a disjunct (amphitropical) distribution between temperate South and North America (see Knapp et al. 2019). In South America it is only known from Argentina (Provs. Buenos Aires, Chubut, Córdoba, La Pampa, Mendoza, Neuquén, Río Negro, San Juan, San Luis, Santa Cruz), largely in Patagonia. The species has been introduced outside its native range in temperate areas of Europe, South Africa and Australia (see Särkinen et al. 2018).

Ecology and habitat.

Solanum triflorum shows broad ecological lability, growing along roadsides, sandy soils, in cultivation, and in salt plains (salinas) between (0-)700 and 2,900 m elevation..

Common names and uses.

Argentina. Córdoba: meloncillo (Kurtz 4612). In North America berries eaten in times of famine and used medicinally (see Knapp et al. 2019); no uses have been recorded from South American specimens.

Preliminary conservation status

( IUCN 2022). Least Concern [LC]. EOO = 92,225,775 km2 [LC]; AOO = 3,708 km2 [EN]; calculated on global range. Solanum triflorum is weedy and common where it occurs ( Särkinen et al. 2018, Knapp et al. 2019). In Patagonia it is common along roads and in highly disturbed sites.

Discussion.

Solanum triflorum is a distinctive species with a prostrate habit, fleshy, usually pinnatifid, leaves, and deeply stellate flowers with long, thin anthers. The inflorescences usually have a small bracetole at the apex and berry size varies from small (ca. 10 mm) to very large (ca. 20 mm), but usually a given plant has either small or large berries. Numerous stone cells are found in the berries, sometimes almost outnumbering seeds, and large berries can have as many as 30 stone cells. Solanum triflorum is difficult to confuse with any other morelloid solanum. It was thought to be related to members of the Radicans clade based on morphology ( Child 1994) but molecular data refute this and place the species as the first branching species of the Black nightshade clade (sensu Särkinen et al. 2015b).

Leaf shape can be quite variable in S. triflorum although not within individual plants. Most plants have deeply dissected leaves, but some (e.g., Knapp et al. 10488 and Kurtz 5534b from Prov. Mendoza, Argentina, Chiapella et al. al. 1809 from Prov. Neuquén, Argentina) have leaves that are only shallowly toothed. The glandular trichomes reported on leaves of S. triflorum ( Subils 1989) are very sparse and never give the plants a viscid, sticky feel.

Solanum triflorum has a classic American Amphitropical Distribution ( Gray and Hooker 1880; Raven 1963; AAD sensu Simpson et al. 2017), with populations occuring in North and South America, but not between (see also S. nitidibaccatum ). Due to its weedy nature, it is often assumed to be introduced to North America (see discussion in Knapp et al. 2019), but the amphitropical distribution pattern is found in other Solanaceae native to both regions such as Lycium L. ( Levin et al. 2007) and groups of solanums such as the Carolinense (subsection Lycium Lathyrocarpum G.Don, Wahlert et al. 2015, as “section”) and Elaeagnifolium ( Knapp et al. 2017) clades. Solanum elaeagnifolium Cav. (Elaeagnifolium clade, Knapp et al. 2017) has an almost identical amphitropical distribution (AAD sensu Simpson et al. 2017), and is similarly weedy; it has also been assumed to be introduced to North America. Distribution of these disjunct group is more likely to be the result of long distance dispersal than of vicariance ( Guilliams et al. 2017), with dispersal after being eaten and passing through an animal’s gut (endozoochory) being less common than disperal via attachment to an animal fur or feathers (epizoochory) ( Schenk and Saunders 2017). In the case of Solanaceae , soft juicy berries make endozoochory more likely as a distribution mechanism, although there is no information on frugivores or fruit dispersal for S. triflorum . The distribution of S. triflorum in temperate areas, but also at higher elevations in deserts and into the more boreal regions of North America places it in the temperate AAD category of Simpson et al. (2017); annuals like S. triflorum predominate in this category. Amongst temperate AAD species the most common direction for distribution is from North to South America, but we suspect that like Verbenaceae ( Frost et al. 2017) and Lycium ( Levin et al. 2007), most Solanum disjunctions will have a South America to North America directionality. To date, only North American populations of S. triflorum have been included in molecular phylogenetic studies ( Särkinen et al. 2015b).

Hunziker (1989) inadvertently lectotypifed (sensu Prado et al. 2015) S. triflorum in a note added in proof referring to a photocopy of the holotype from PH. Barboza et al. (2013) and Särkinen et al. (2018) superfluously lectotypified the synonyms S. mendocinum and S. calophyllum respectively; these names had also been inadvertently lectotypified by Hunziker (1989) via citation of a single specimen in a single herbarium.

Figures

Figure 4. Representative fruits, seeds and stone cells of South American morelloids A bilobed fruits in S. tripartitum with fully mature red berries at the base of the inflorescence and maturing green, yellow, and orange fruits more distally B orange-red fleshy berries of S. corymbosum in highly branched inflorescences C fully mature marbled fruits in S. physalifolium D immature ellipsoid fruits of S. antisuyo E fully mature fruits of S. antisuyo F immature green fruits amongst fully mature purple-black fruits in S. cochabambense G fully mature fruits of S. polytrichostylum H stone cells (also known as sclerotic granules or brachysclerids) found in the fruits of most species of the Morelloid clade (left side of photo) next to the teardrop shaped seeds (right side of photo; S. umalilaense Manoko) I stone cells visible in dried fruits of herbarium specimens (S. triflorum). (A Barboza 3563 B Saerkinen et al. 4604 B C Knapp et al. 10334 D Gonzales 10256 E Gonzales 10256 F Knapp et al. 10363 G Saerkinen et al. 5277 H Nijmegen accession A 24750133 I Podlech 8624 BM 000848286). Photos by P. Gonzales, S. Knapp, and T. Saerkinen.

Figure 172. Solanum triflorum A flowering habit B fruiting habit C flowering branch D detail of adaxial leaf surface E detail of adaxial leaf surface F flower bud G flower H fruit (A, C, F, G Donat 55 B, D, E, H Baker 577). Illustration by R. Wise. Previously published in Saerkinen et al. (2018: 169) and Knapp et al. (2019: 118).

Figure 173. Solanum triflorum A habit B flowering habit C flower bud and flower D flower (A Sersic 5040 B, D Knapp et al. 10488 C Barboza et al. 2345). Photos by G. Barboza, S. Knapp and A. Sersic. Partly previously published in Saerkinen et al. (2018: 170) and Knapp et al. (2019: 119).

Figure 174. Distribution map of Solanum triflorum in South America. For distribution in North America and the Eastern Hemisphere, see Knapp et al. (2019: 120) and Saerkinen et al. (2018: 171), respectively.