Solanum annuum C.V.Morton, Revis. Argentine Sp. Solanum 102. 1976.

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

5. Solanum annuum C.V.Morton, Revis. Argentine Sp. Solanum 102. 1976.

Figs 3B , 18 , 19

Solanum micrantherum Cabrera, Hickenia 1(31): 168. 1978. Type. Argentina. Catamarca: Andalgalá, El Candado, P. Jörgensen 978 (holotype: SI [003327]; isotypes: CORD [CORD00006989, fragment], GH, MO [MO-2127099, acc. # 818835], US [028337125, acc. # 921698]).

Type.

Argentina. Salta: Dpto. Rosario de Lerma, Campo Quijano , 17 Jan 1929, S. Venturi 8507 (holotype: US [00027454, acc. # 1549043]).

Description.

Tiny annual herbs 0.05-0.5 m high, erect or, if larger, the plants spreading. Stems terete, often drying purple, moderately pubescent with eglandular, white simple uniseriate trichomes ca. 0.5 mm long, these antrorse; new growth densely pubescent with eglandular white simple uniseriate trichomes like those of the stems; older stems greenish brown. Sympodial units difoliate or trifoliate, the leaves not geminate. Leaves simple to deeply pinnatifid, both types present on single stems, the blades (1)1.5-5 cm long, (0.5)0.6-2.5 cm wide, ovate to ovate-elliptic in outline, widest in the lower third, membranous, concolorous; adaxial surfaces sparsely pubescent with eglandular white simple uniseriate trichomes to 0.5 mm long like those of the stems; abaxial surfaces similarly sparsely pubescent but the trichomes denser along the veins; principal veins 3-4 pairs, corresponding to numbers of lobes in pinnatifid leaves; base acute to somewhat attenuate along the petiole; margins entire to deeply pinnatifid, entire leaves often at base of plant, the lobes long-triangular with rounded tips, the sinuses reaching nearly to the midrib in the most deeply pinnatifid leaves; petiole 0.2-1.5 cm long, sparsely pubescent with eglandular simple uniseriate trichomes like those of the stems. Inflorescences opposite the leaves, unbranched or rarely forked, 1.5-5 cm long, with 5-12 flowers, sparsely pubescent with eglandular simple white uniseriate trichomes ca. 0.5 mm long; peduncle 0.6-5 cm long; pedicels 0.7-0.9 cm long, ca. 0.5 mm in diameter at the base, ca. 0.5 mm in diameter at the apex, filiform and spreading, sparsely pubescent with simple uniseriate trichomes like the rest of the inflorescence, articulated near the base, leaving a small raised stump on the inflorescence axis; pedicel scars irregularly spaced 1.5-5 mm apart. Buds globose, the corolla halfway exserted from the corolla tube before anthesis. Flowers 5-merous, cosexual (hermaphroditic). Calyx tube 0.75-1 mm long, conical, the lobes 1-2 mm long, ca. 1 mm wide, deltate or very rarely triangular, sometimes somewhat unequal in size, the apices rounded or rarely acute, sparsely pubescent with eglandular simple uniseriate trichomes ca. 0.5 mm long like those of the pedicel. Corolla 0.7-1.5 cm in diameter, white to pale lavender, pentagonal to very shallowly stellate, lobed ca. 1/4 of the way to the base, the lobes 1.5-2.5 mm long, 3-4 mm wide, spreading at anthesis, glabrous on both surfaces but with a few unicellular papillae on the lobe tips. Stamens equal; filament tube ca. 0.5 mm long; free portion of the filaments 1-1.5 mm long, densely pubescent with tangled eglandular simple uniseriate trichomes abaxially, the trichomes with verrucose surfaces; anthers 2.5-4 mm long, 0.75-1 mm wide, ellipsoid, yellow, poricidal at the tips, the pores lengthening to slits with age. Ovary conical, glabrous; style (3.5)5.5-7 mm long, straight, often included in the anther cone, densely pubescent in the lower 2/3 to 1/2; stigma capitate, the surface minutely papillate. Fruit a globose berry, 0.25-0.3 cm in diameter, green when mature, the pericarp thin, matte, opaque, glabrous; fruiting pedicels 0.25-0.8 cm long, ca. 0.5 mm in diameter at the base, not markedly woody, pendent or deflexed, not persistent; fruiting calyx accrescent but not covering the berry, instead spreading as a subtending open cup, the tube to 4 mm long, the lobes 3-4 mm long, 3-4 mm wide, rounded. Seeds 1-2 per berry, 2.5-2.6 mm long, 2.1-2.5 mm wide, rounded and only slightly flattened, dark brown, the surfaces minutely pitted and tuberculate, the testal cells rectangular in outline. Stone cells absent. Chromosome number: n = 12 ( Moscone 1992; voucher Hunziker 24901, as S. nicandricalyx ).

Distribution

(Fig. 20 ). Solanum annuum is endemic to northern Argentina (Prov. Jujuy, Salta, Tucumán, and Catamarca).

Ecology and habitat.

Solanum annuum is found in prepuna and puna habitats, often in open and disturbed areas; from 2,100 to 3,300 m elevation.

Common names and uses.

None recorded.

Preliminary conservation status

( IUCN 2022). Vulnerable [VU - B2 a,b(iii, iv), D2]). EOO = 25,287 km2 [LC]; AOO = 72 km2 [EN]. The large EOO of S. annuum suggests it is not of particular conservation concern, and the smaller AOO is perhaps the result of collecting deficit. We suggest this species warrants some concern as it occurs in fewer than five sites and populations are small and widely dispersed; most collections have been made in the area of Tafí del Valle.

Discussion.

Solanum annuum is a distinctive species; it is small annual herb with leaves that are extremely variable in shape even on the same plant (Fig. 19A ). The inflorescence is long and filiform, and the calyx is a spreading cup, somewhat like those of S. weddellii and S. gilioides . Unlike those taxa, however, the calyx does not become accrescent and fully envelop the fruit but remains an expanded plate-like structure subtending the tiny berry (Fig. 19D ). Morton (1976) thought S. annuum was related to S. salicifolium (as S. incisum ) by virtue of its pedunculate, multiflowered inflorescence and often incised leaf shape and placed it in his sect. Solanum Dulcamara p.p.; Cabrera (1978) suggested it was probably a member of sect. Solanum Campanulisolanum and related to S. sinuatiexcisum and S. fiebrigii , based on its rotate/campanulate corolla. Habit (small annual herbs vs. shrub or perennial herbs), corolla shape (pentagonal-rotate versus deeply stellate) and anther size (1.2-2.7 mm long vs 3.5-5 mm long) easily distinguish S. annuum from S. salicifolium , while the number and ornamentation of the seeds (two tuberculate seeds vs. many minutely pitted seeds) easily distinguish it from S. sinuatiexcisum and S. fiebrigii . Barboza (2003) treated S. annuum as a member of section Solanum Chamaesarachidium , along with S. gilioides and S. weddellii (as S. chamaesarachidium ) with which it shares the herbaceous habit, accrescent calyx in fruit and tuberculate seeds. The calyx is less accrescent in S. annuum than in the other two taxa included by Barboza (2003) and the single-seeded locules of S. annuum are unique in morelloids. In molecular phylogenetic analyses ( Särkinen et al. 2015b; Gagnon et al. 2022) S. annuum is a member the Black nightshade clade but is not sister to S. gilioides and S. weddellii , the two other morelloid species with tuberculate seeds. Within the Black nightshade clade it is in an unresolved polytomy involving S. furcatum and the rest of the clade (see fig. 2 of Särkinen et al. 2015b), suggesting that the tuberculate seeds may be homoplasious.

Figures

Figure 3. Representative flowers of South American morelloids A campanulate purple corollas in forked internodal inflorescences in S. fiebrigii B pentagonal white corollas in S. annuum C broadly stellate purple corollas with long-exerted styles in S. pentlandii D broadly stellate white corollas with slightly exerted globose stigmas in S. radicans E deeply stellate pale yellow corollas in S. huayavillense F deeply stellate purple corollas with dark central eye colouration in S. salicifolium G bumblebee visiting and buzzing the anther cone in S. cochabambense H variation in corolla shape, size and colouration within a single individual of S. cochabambense (A Barboza et al. 3548 B Barboza et al. 3495 C Knapp et al. 10248 D Knapp et al. 10277 E Barboza et al. 3531 F Chiarini et al. 819 G Saerkinen et al. 4036 H Knapp et al. 10669). Photos by S. Knapp and T. Saerkinen.

Figure 18. Solanum annuum A plant B flower C glandular trichome of the calyx D eglandular trichome of the calyx E dissected flower F stamen, dorsal view G stamen, ventral view H gynoecium I eglandular trichome of the style J apex of the style and stigma K ovary, longitudinal section L fruit M seed N embryo (A-N Hunziker et al. 24901). Illustration by L. Ribulgo. Previously published in Barboza et al. (2013: 238).

Figure 19. Solanum annuum A habit B flowering stem with dissected leaves C flowering stem with entire leaves D developing fruits surrounded by accrescent calyx (A-D Barboza et al. 3495). Photos by S. Knapp.

Figure 20. Distribution map of Solanum annuum.