Solanum weddellii Phil., Anales Mus. Nac. Chile, Segunda Secc., Bot. 1891: 65. 1891.

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

60. Solanum weddellii Phil., Anales Mus. Nac. Chile, Segunda Secc., Bot. 1891: 65. 1891.

Figs 2A , 181 , 182

Chamaesaracha boliviensis Dammer, Bot. Jahrb. Syst. 49: 215. 1913. Type. Bolivia. La Paz: Between Palca and La Paz, K. Pflanz 145 (holotype: B, destroyed [F neg. 2710]). Bolivia. La Paz: Prov. Ingavi, cantón Jesus de Machaca, comunidad Titicani-Tacaca, a 20 km de Guaqui, 3820 m, 22 Mar 1989, X. Villavencio L. 318 (neotype, designated here: LPB; isoneotype: CORD [CORD00101735]).

Solanum chamaesarachidium Bitter, Repert. Spec. Nov. Regni Veg. 15: 94. 1917. Type. Based on Chamaesaracha boliviensis Dammer.

Type.

Chile. Región I ( Tarapacá): Prov. Tarapacá, Calcalhuay , Jan 1886, C. Rahmer s.n. (no herbaria cited; lectotype, designated here: SGO [SGO000004605]; isolectotype: WU [acc. # 1903-0010229]) .

Description.

Tiny annual herbs to 0.2 m high, usually appearing as a prostrate rosette. Stems terete, sparsely pubescent with eglandular, 2-4-celled simple uniseriate trichomes to 0.5 mm long, these antrorse and slightly verrucose, and shorter 1-2-celled glandular trichomes to 0.2 mm long; new growth sparsely to densely pubescent with tangled, weak-walled eglandular simple uniseriate trichomes; older stems green. Sympodial units plurifoliate, the leaves not geminate. Leaves simple, shallowly to deeply lobed, the blades 1-3(4) cm long, 0.5-1.5(2) cm wide, elliptic to narrowly elliptic in outline, widest at the middle, thick and somewhat fleshy in live plants, concolorous; adaxial and abaxial surfaces sparsely pubescent with tangled, eglandular simple uniseriate trichomes to 0.5 mm long, these denser on the veins; principal veins 3-4 pairs, not clearly visible (except as lobes) in live plants; base attenuate onto the winged petiole; margins shallowly to deeply lobed, revolute and undulate, the sinuses reaching 1/4-3/4 of the distance the midrib, the lobes triangular with deltate, rounded tips; petiole 0.4-1.5 cm long, winged from the attenuate leaf base. Inflorescences internodal, sometimes very near the nodes and then appearing almost opposite the leaves, unbranched, 0.3-1 cm long, with 3-5 flowers clustered at the tip, a single flower open at a time, sparsely to moderately pubescent with tiny glandular papillae and longer eglandular simple uniseriate trichomes to 0.5 mm long like those of the stems; peduncle 0.25-0.9 cm long; pedicels 0.2-0.4 cm long, ca. 0.25 mm in diameter at the base, ca. 0.25 mm in diameter at the apex, erect at anthesis, sparsely to moderately pubescent with a mixture of glandular papillae and tangled simple uniseriate trichomes like the rest of the inflorescence, articulated at the base; pedicel scars clustered or to ca. 1 mm apart, occasionally to as much as 4 mm apart in larger inflorescences. Buds ellipsoid, the corolla ca. halfway exserted from the calyx before anthesis (only just surpassing the tips of the calyx lobes). Flowers 5-merous, cosexual (hermaphroditic). Calyx tube 1-1.5 mm long, conical, the lobes 1.1.5 mm long, 1-1.5 mm wide, deltate with rounded tips, sparsely pubescent with a mixture of glandular papillae and 2-4-celled eglandular simple uniseriate trichomes. Corolla ca. 0.6 cm in diameter, purple or white (fading with flower age through anthesis) with a large greenish yellow, purple-edged central eye, rotate, lobed less than 1/4 of the way to the base, the lobes (acumens) ca. 1 mm long, ca. 1 mm wide, spreading at anthesis, adaxially glabrous except for the papillate lobe tips, abaxially with scattered eglandular simple uniseriate trichomes over the entire surface. Stamens equal; filament tube minute; free portion of the filaments 0.5-0.7 mm long, densely pubescent with tangled simple uniseriate trichomes adaxially; anthers ca. 1 mm long, ca. 1 mm wide, globose to broadly ellipsoid, yellow, poricidal at the tips, the pores lengthening to slits with age. Ovary conical, glabrous; style ca. 1.5 mm long, straight, only just exceeding the anther cone, densely papillate in the lower 3/4 of its length; stigma large-capitate and globose, ca. 1 mm in diameter, the surface minutely papillate, bright green in live plants. Fruit a globose berry, 0.5-0.7 cm in diameter, pale green to pale whitish green at maturity, the pericarp thin, matte, opaque, glabrous; fruiting pedicels 0.6-0.7 cm long, ca. 0.5 mm in diameter at the base, ca. 1 mm in diameter at the apex, not markedly woody, deflexed with the berry pointing down to rest on the soil, not persistent; fruiting calyx accrescent and inflated, the calyx tube ca. 0.5 cm long strongly angled between the lobes, the lobes ca. 0.5 cm long, 0.5-0.6 cm wide, more or less halfmoonshaped to deltate, the margins somewhat overlapping, the venation prominent and slightly purplish black or dark green in live plants, darker in dry specimens, the berry always visible inside the inflated calyx. Seeds 2-7(17) per berry, 2-3 mm long, 1-2 mm wide, irregularly shaped to somewhat teardrop shaped, not markedly flattened, black to dark brown, the surface tuberculate, the testal cells pentagonal in outline. Stone cells absent. Chromosome number: 2n = 24 ( Chiarini et al. 2017, voucher Särkinen et al. 4038).

Distribution

(Fig. 183 ). Solanum weddellii occurs in the high Andes of Peru (Depts. Arequipa, Cusco, Huancavelica, Moquegua, Puno), Bolivia (Depts. La Paz, Potosí), Argentina (Provs. Catamarca, La Rioja, Jujuy, Salta, Tucumán) and Chile (Regions I [ Tarapacá], II [Antofagasta]).

Ecology and habitat.

Solanum weddellii is a plant of open sandy areas above treeline in the puna or high elevation semi-desert (xerophytic) habitats, growing in loose sandy soil among gravel and with other small herbs, from 2,300 to 4,550 m elevation.

Common names and uses.

None recorded.

Preliminary conservation status

( IUCN 2022) Vulnerable [VU, B 2a,b(iv), D2]. EOO = 603,950 km2 [LC]; AOO = 220 km2 [EN]. Solanum weddellii has a large extent of occurrence but grows only in very loose sandy soils in widely dispersed populations. It is known from fewer than ten sites. Given these parameters we would suggest it is of some conservation concern. It is known to occur within protected areas in Argentina (e.g., Humahuaca World Heritage site) but is often collected in areas around mining operations; whether this is an access issue or more related to the soil type specificity of S. weddellii is not known.

Discussion.

Solanum weddellii is morphologically very similar to S. gilioides and it can sometimes be difficult to distinguish them from fragmentary herbarium specimens. The most striking differences are in calyx shape through anthesis and fruit development. In flower, the calyx lobes of S. gilioides are linear or narrowly triangular and grow considerably in length when fruiting (Fig. 62G, H ), while those of S. weddellii are more ovate-deltate and expand in width in fruit, forming a broadly open, somewhat frilly-looking cup (Fig. 182D ). Leaves of S. weddellii are more densely pubescent and usually less deeply divided than those of S. gilioides and flowers are smaller (ca. 0.6 cm in diameter with anthers ca. 1 mm long in S. weddellii versus ca. 1.6 cm in diameter with anthers 1-3 mm long in S. gilioides ). These two species were previously recognised as section Solanum Chamaesarachium Bitter ( Barboza 2003), along with S. annuum . Molecular data confirm the close relationship of S. weddellii and S. gilioides as the monophyletic Chamaesarachidium clade ( Särkinen et al. 2015b), but S. annuum is not related to them ( Gagnon et al. 2022).

Plants of S. weddellii vary enormously in size even in similar habitats; this may be due to local microenvironmental differences. The patchy distribution of S. weddellii may be due to its preference for loose sandy soils; we have only collected it in high elevation areas with sand soil or dune-like habitats; S. gilioides in contrast is found in a wide variety of rocky and sandy areas.

No herbaria were cited in the original description of S. weddellii ; we have selected a specimen in SGO (SGO000004605) corresponding to the collector, locality and date from the protologue as the lectotype.

We have found no duplicates of the Pflanz collection used to describe Chamaesaracha boliviensis and it is likely to have been a sheet in Berlin that was destroyed (B, F neg. 2710), but no herbaria were cited in the protologue ( Dammer 1913). Barboza et al. (2013) did not neotypify this name, but we here select a fruiting collection gathered in March from the vicinity of La Paz, Bolivia (Villavicencio L. 318, LPB) as the neotype for this name.

Figures

Figure 2. Representative habits and leaves of South American morelloids A prostrate annual herbs (S. weddellii) B large lax shrubs (S. aloysiifolium) C roots forming along a creeping stem (S. juninense) D spinose processes on stems of many species (S. huayavillense) E glandular trichomes found in some members of the clade (S. glandulosipilosum) F dendritic / branched trichomes found in S. pallidum G regularly 3 - lobed leaves in S. palitans H highly variable leaves along a single stem in S. salicifolium (A Saerkinen et al. 4038 B Barboza et al. 3505 C Saerkinen et al. 4754 D Barboza et al. 3536 E Barboza et al. 3520 F Saerkinen et al. 4010 G Atchison & Gagnon 25 H Barboza et al. 3473). Photos by S. Knapp, G. Atchison, and T. Saerkinen.

Figure 62. Solanum gilioides A habit B flowering plant showing different leaf shapes and annual habit C detail of adaxial leaf surface D detail of abaxial leaf surface E trichomes on leaves F flower bud G dissected flower H maturing fruit with inflated calyx I seed (A, C, D, H Wood et al. 21974 B, F, G Wood et al. 19056 E, I Negritto et al. 429). Illustration by R. Wise and L. Ribulgo.

Figure 181. Solanum weddellii A habit B flower bud C, D glandular trichomes of the calyx E eglandular trichome of the calyx F section of a dissected flower G stamen, lateral view H stamen, dorsal view I stamen, ventral view J glandular trichome of the filament K gynoecium L papilla of the style M fruit N seed O seed cross section P embryo (A-P Krapovickas 6219). Illustration by N. de Flury. Previously published in Barboza et al. (2013: 241) as S. chamaesarachidium.

Figure 182. Solanum weddellii A habit B flowering and fruiting branch C flower at full anthesis D maturing fruits (A, D Saerkinen et al. 4038 B Cano et al. 20615 C Barboza et al. 3475). Photos by A. Cano, S. Knapp and T. Saerkinen.

Figure 183. Distribution map of Solanum weddellii.