Solanum robustum H.Wendl.

Solanaceae, Jennifer M Edmonds. Oliganthes, Melongena & Monodolichopus, Maria S. Vorontsova & Sandra Knapp. Flora of Tropical East Africa. 2012

Type

Type: Brazil; type specimen not specified

Morphology General

Shrub or perennial herb to 5 m high; all stems ferrugineous with a dense indumentum of intertwined stalked stellate hairs to 1.5 mm diameter, up to 9-rayed with long central rays, stalks 0–2 mm long, mixed with sessile brown glands; main stems and branches with scattered stout sharp yellow pyramidal prickles to 1.5 × 1.8 mm

Morphology Leaves

Leaves alternate or opposite, often thick and soft, dark green above, yellow to brown below with orange to brown veins and midrib, ovate, 12–27 × 9–24 cm, bases cordate and oblique, margins deeply sinuate-dentate with 2–4 broadly triangular acute lobes to 6 cm deep, apices acute; upper surfaces stellate-pubescent, hairs thicker and interwoven on midrib and main veins, lower surfaces densely stellatepubescent, the interwoven hairs with unequal rays to 1.3 mm long; scattered prickles present on midribs and upper main veins; petioles 3–20 cm long, decurrent and with wings up to 1.5 cm wide often extending down to next node, with scattered prickles to 2 cm long below

Morphology Reproductive morphology Inflorescences

Inflorescences subterminal to lateral, simple, few- to 20-flowered, lax, helicoid cymes; flowers ?andromonoecious, 5merous, becoming lax in fruit; axes densely ferrugineous, hairs on stems mixed with small glandular hairs; peduncles erect and 1.2–4.5 cm long, with prickles; pedicels usually erect, sometimes recurved apically and 0.5–1.4 mm long in flower, spreading and 1–1.8 cm in fruit

Morphology Reproductive morphology Flowers Calyx

Calyx green, campanulate/cupulate, 5–9 mm long, stellate-pubescent and with sessile glands externally and internally; lobes lanceolate, 5–9 × 1.8–3.4 m, acute, reflexed between corolla lobes, appressed becoming reflexed in fruit and 5–10 × 2–4.5 mm

Morphology Reproductive morphology Flowers Corolla

Corolla white, with a contrasting basal star and median veins, stellate, 1.5–2.1 cm radius; tube ± 1 mm long, glabrous; lobes lanceolate to narrowly lanceolate, 7–15 × 2–3.5 mm, stellatepubescent externally, acute with apical tufts of small hairs, glabrous internally except for occasional hairs on veins, corolla reflexed exposing androecium after anthesis

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens equal or unequal; filaments free for 1–3.5 mm, often varying in same flower, glabrous; anthers yellow to brownish, poricidal, 5–7 × 1–1.8 mm, connivent

Morphology Reproductive morphology Flowers Gynoecium Ovary

Ovary 1.2–2.6 × 1.4–2.5 mm, pubescent with long appressed silky hairs, bilocular; style straight, either enclosed at base of staminal tube when 1.2–3.5 × 0.25–1 mm, or 9–10 × 0.4–0.6 mm when exserted up to 4 mm, pubescent with scattered stellate and small simple glandular hairs in lower half; stigma capitate, 0.2–1 mm diameter. Berries dark green becoming black, globose, 1.2–2 cm diameter, rusty tomentose with simple silky appressed hairs, glabrescent apically

Morphology Reproductive morphology Seeds

Seeds > 100, dark brown, obovoid, reniform to orbicular, 1.7–2 × 1.2–1.4 mm, rounded not flattened, reticulate; sclerotic granules absent.

Ecology

Secondary vegetation, old cultivation, shamba edges, moist forest margins and clearings, plantations, roadsides; 500–2150 m

Note

Nee (in Nee et al. (eds), Solanaceae IV: 321 (1991)) commented that species belonging to the group/section Erythrotrichum constitute the most difficult of those in the subgenus Leptostemonum, with its species being difficult to differentiate from those in the section Micracantha. Solanum robustum has been introduced into Africa from S America and is commonly known as the White Potato. Although cultivated as an ornamental this species has become a troublesome weed as an escape from cultivation in T 3 and T 6. Solitary plants of S. robustum have been reported but it often grows in groups which can form impenetrable masses of viciously spiny vegetation. These spines and the dense ferrugineous pubescence composed of varied and complex hairs characterise this species. Not only do stalks and rays of the stellate hairs vary considerably in length, but stalks can also be invested with small spreading multicellular glandular hairs. Plants of this species are reportedly used to treat gonorrhoea and worms in Lushoto.

Distribution

Flora districts: T3 T6 Range: Native to Brazil, Paraguay and Argentina, also recorded from Reunion and Java Range: Cultivated and now a successful escape which has become locally common