Solanum juvenale

Citation author:

Thell.

Citation:

Repert. Spec. Nov. Regni. Veg. 5: 161. 1908.

Type:

FRANCE. Herault, Port-Juvénal, près Montpellier (séchoirs à laine), Aug 1894 (fl), J. A. Daveau s. n. ([first-step] lectotype: designated by C. V. Morton, Revis. Argentine Sp. Solanum: 236. 1976; [second-step] lectotype, designated here: MPU–MPU022907!; isolectotypes: CAS–CAS0005763 [scan!], MPU–MPU022904!, MPU–MPU022905!).

Last edited by:

Greg Wahlert, Franco Chiarini and Lynn Bohs

Written by:

Greg Wahlert, Franco Chiarini and Lynn Bohs

Habit:

Erect to decumbent perennial herb up to 0.5 m tall; stems often branched at the base; roots producing buds. Stems moderately pubescent with sessile stellate hairs 0.2–0.4 mm in diameter with 4–8 lateral rays, the central ray absent or up to 0.3 mm long, moderately to densely armed with straight tapered prickles up to 6 mm long.

Sympodial structure:

Sympodial units 2- to 3-foliate, sometimes plurifoliate, the leaves not geminate.

Leaves:

Leaves simple, the blades 1.8–5.5 × 1–2.5 cm, oblong-elliptic in outline, somewhat discolorous, densely stellate-pubescent abaxially, sparsely so adaxially with hairs like those of the stems, moderately armed with prickles up to 8 mm long on the major veins abaxially and adaxially; base cuneate; margin sinuate to moderately lobed with 3–6 lobes per side; apex acute; petioles 0.5–3 cm long, moderately to densely stellate-pubescent and armed with prickles up to 7 mm long.

Inflorescences:

Inflorescences ca. 1–4 cm long, extra-axillary, unbranched, with 1–3(5) flowers, the axes moderately to densely stellate-pubescent, moderately armed with prickles up to 2.5 mm long; peduncle 2–3 cm long or absent, with the lowermost flower(s) emerging directly from the node; pedicels 1–2 cm long in flower, 1–3 cm long and curved downward in fruit, articulated at the base, moderately to densely stellate-pubescent and armed with prickles up to 3.5 mm long.

Flowers:

Flowers 5-merous, all apparently perfect. Calyx 7–8 mm long, the tube 2–4 mm long, the lobes 4–6 × 1.5–3 mm, narrowly deltate, the apex acute-acuminate, densely stellate-pubescent, densely armed with prickles up to 5 mm long abaxially, glabrous adaxially; fruiting calyx somewhat accrescent but not completely covering the fruit, 10–16 mm long, the tube ca. 3 mm long, the lobes 7–12 × 4–5.3 mm, narrowly triangular, moderately stellate-pubescent and armed with prickles up to 4.5 mm long. Corolla 1.2–3 cm in diameter, 15–17 mm long, stellate to stellate-pentagonal, chartaceous, white or bluish, the tube 4–8 mm long, the lobes 4–9.5 × 4–7 mm, deltate to triangular, the apex acute, densely stellate-pubescent abaxially, glabrous adaxially. Stamens with filaments 1–1.7 × 0.2–0.3 mm; anthers 5–6.5 × 1.2–1.4 mm, narrowly lanceolate, not connivent, yellow, the pores directed distally. Ovary 1.2–1.5 × 1.3–1.5 mm, subglobose, glabrous; style 7–12 × ca. 1 mm, cylindrical, straight, glabrous, exserted; stigma capitate.

Fruits:

Fruit an ellipsoid, ovoid or globose berry, 1–1.9 × 0.8–1.4 cm, the apex obtuse, green with white stripes when immature, yellow at maturity, glabrous.

Seeds:

Seeds numerous, ca. 2.4 × 1.9 mm, flattened-reniform, lenticular, yellow, the testal surface finely foveolate.

Chromosome number:

Chromosome counts have shown Solanum juvenale to be a tetraploid, with a gametophytic count of n = 24 (E. A. Moscone 75; Moscone 1992) and a sporophytic count of 2n = 48 (F. Chiarini 503; F. Chiarini 504; Chiarini 2007).

Distribution:

Solanum juvenale is restricted to the central and Pampas provinces of Argentina from 400 to 1,100 m in elevation. It grows in disturbed areas such as roadsides, borders of cultivated fields, and waste areas, and can become a localized weed. It typically prefers relatively drier sites than the closely related S. aridum.

The type (J. A. Daveau s. n.) was collected near the old Port of Juvénal on the River Lez, near Montpellier, France. The plants were found growing in woolen waste (séchoirs à laine) which was probably imported from the Buenos Aires area. Notes on MPU specimens collected from 1868 to 1894 indicate that S. juvenale was adventive around the port or bridge at Juvénal and the customs post at Latte near Montpellier. It was growing as a weed in the Jardin des Plantes in Montpellier during 1904 to 1949, but L. Soudan indicates that it had disappeared from the port and garden by 1970. It was not seen in the Jardin in Montpellier during a visit by LB in 2004.

Phenology:

The species flowers between October and March and fruits between November and May.

Phylogeny:

Solanum juvenale is a member of the Carolinense clade (sensu Stern et al. 2011) [section Lathryocarpum]. Relationships amongst species in the group have been analyzed by Wahlert et al. (2014).

Commentary:

In habit and reproductive characters, Solanum juvenale resembles S. aridum, and intermediate forms can be found where the two species' ranges overlap (Morton 1976; Chiarini 2007). Solanum juvenale can be separated from S. aridum by the moderate to dense distribution of prickles on the stem, petioles, leaf blades, inflorescence axes, pedicels, and especially calyces, whereas S. aridum is unarmed or sparsely armed. The prickles on the leaf blades are usually much longer in S. juvenale (up to 8 mm long), whereas in S. aridum they are up to 3 mm long. Solanum juvenale also has smaller leaf blades (1.8–5.5 × 1–2.5 cm) that are more deeply lobed compared to the larger leaf blades of S. aridum (2–10 × 1–5 cm) that are shallowly lobed to sinuate. The ploidy level consistently differs between the two species, with S. juvenale being 2n = 48 and S. aridum being 2n = 24. Experimental crosses in the greenhouse between S. aridum and S. juvenale produced triploid plants (2n = 36; Chiarini 2007).

In the protologue of Solanum juvenale Thellung listed three syntypes. Later, Morton (1976) chose the Daveau s. n. collection at MPU—which consists of three specimens—as the lectotype. When a lectotype refers to a single collection or gathering, but consists of more than one specimen, Article 9.17 of the ICBN (McNeill et al. 2012) allows for a subsequent (i.e., second-step) lectotypification to narrow the designation to a single specimen. In this case, Morton (1976) designated the Daveau s. n. collection at MPU as the first-step lectotype, and we have further narrowed it via a second-step lectotypification to the specimen Daveau s. n. (MPU–MPU022907). This specimen is the most complete of the three bearing several flowers and it was also annotated as "Solanum juvenale n. spec." in Thellung's handwriting.

References:

Barboza, G. E. 2013. Solanaceae. Pp. 1–350 in Flora vascular de la República Argentina, Vol. 13, eds. A. M. Anton and F. O. Zuloaga. San Isidro, Argentina: Instituto de Botánica Darwinion, Instituto Multidisciplinario de Biología Vegetal.

Chiarini, F. E. 2007. Estudios multidisciplinarios en las especies de Solanum subgen. Leptostemonum de Argentina y regions limítrofes, con especial referencia a su taxonomía. Ph.D. Dissertation. Córdoba, Argentina: Universidad Nacional de Córdoba.

Matesevach, M. 2002. Solanaceae, parte 12. Solanum subgen. Leptostemonum. Flora Fanerogámica Argentina 79: 1–35.

Morton, C. V. 1976. A revision of the Argentine species of Solanum. Córdoba: Academia Nacional de Ciencias.

Moscone, E. A. 1992. Estudios de cromosomas meióticos en Solanaceae de Argentina. Darwiniana 31: 261–297.

Stern, S., M. F. Agra, and L. Bohs. 2011. Molecular delimitation of clades within New World species of the "spiny solanums" (Solanum subg. Leptostemonum). Taxon 60: 1429–1441.

Wahlert, G. A., F. Chiarini, and L. Bohs. 2014. Phylogeny of the Carolinense clade of Solanum (Solanaceae) inferred from nuclear and plastid DNA sequences. Systematic Botany 39: 1208–1216.

Common names and uses:

Common names recorded for Solanum juvenale in Argentina are meloncillo de olor, meloncillo del campo, and papa de cuchi (Matesevach 2002; Barboza 2013). The name "meloncillo" refers to the melon-scented fruits.

Conservation status:

While Solanum juvenale is restricted to central and northern Argentina, it nevertheless has a large distribution. It typically grows in highly disturbed habitats, and it is estimated that there will not be any significant reduction in population sizes or locations. With an extent of occurrence of ca. 650,000 km² and area of occupancy of 784 km², Solanum juvenale is assigned a preliminary conservation status of "least concern" (LC).

Taxonomic name:

Solanum juvenale (Solanaceae)

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Solanum juvenale

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