Solanum aculeastrum Dunal

Flora Zambesiaca. Vol. 8, Part 4. Solanaceae. Gonçalves AE. 2005

Morphology General

Shrub or small tree, 1. 2–4.5 m (elsewhere said to reach 8 m), conspicuously armed [or elsewhere unarmed in var albifolium (C H  Wright) Bitter]; hairs stellate, forming a white or cineraceous powdery-looking tomentum on all parts except upper side of the leaves, sessile or subsessile, echinoid, regular, soft, short or minute; prickles brown becoming reddish-brown upwards, to 20 mm long and 15 mm wide at the base, stout and recurved to rarely acicular, very sharp, stellate-felty at base and subglabrous upwards to quite glabrous

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens (4)5–6(10); filaments 0.5–1 mm long; anthers 4–8 mm long, lanceolate-ellipsoid, obtuse basally Stamens (4)5–6(10); filaments 0.5–1 mm long; anthers 4–8 mm long, lanceolate-ellipsoid, obtuse basally.

Morphology Reproductive morphology Flowers Gynoecium Ovary

Ovary 1. 5–3(5.5) × 1–3(5) mm, ± globose or ovoid, ± densely hairy, 2-locular.

Morphology Reproductive morphology Flowers Gynoecium Style

Style 6–8(10) mm long, very much shorter in male flowers, straight, very shortly hairy in the lower half or tomentose to near the apex in male flowers

Morphology Reproductive morphology Fruits

Fruit glossy, greenish becoming yellowish when ripe, later reddish, purplish or brown to blackish, 3.5–5 × 3–5 cm, ± globose to ellipsoid, smooth or warty, ± hairy on upper part, poisonous Fruit glossy, greenish becoming yellowish when ripe, later reddish, purplish or brown to blackish, 3.5–5 × 3–5 cm, ± globose to ellipsoid, smooth or warty, ± hairy on upper part, poisonous.

Morphology Reproductive morphology Seeds

Seeds dirty-yellowish or brownish, 3–5(6) × 2.5–3.5(6) mm, strongly flattened, oblique-reniform or orbicular to ovate or obovate in outline, minutely reticulate all over Seeds dirty-yellowish or brownish, 3–5(6) × 2.5–3.5(6) mm, strongly flattened, oblique-reniform or orbicular to ovate or obovate in outline, minutely reticulate all over.

Morphology General Habit

Shrub or small tree, 1.2–4.5 m (elsewhere said to reach 8 m), conspicuously armed [or elsewhere unarmed in var. albifolium (C.H. Wright) Bitter]; hairs stellate, forming a white or cineraceous powdery-looking tomentum on all parts except upper side of the leaves, sessile or subsessile, echinoid, regular, soft, short or minute; prickles brown becoming reddish-brown upwards, to 20 mm long and 15 mm wide at the base, stout and recurved to rarely acicular, very sharp, stellate-felty at base and subglabrous upwards to quite glabrous.

Morphology Branches

Branches tomentose, gradually glabrescent, the recurved prickles usually conspicuous. Branches tomentose, gradually glabrescent, the recurved prickles usually conspicuous

Morphology Leaves

Leaves solitary, the upper ones often appearing geminate or ternate; petiole (0.3)1–3 cm long; lamina membranous, 3–20 × 1.5–13.5 cm, ovate to elliptic or oblong-lanceolate, sometimes obovate or ± circular, base sub-hastate or truncate, rounded to cuneate, and ± unequal-sided, apex acute to obtuse or acuminate, irregularly sinuate-lobed to divided, the lobes ± triangular to elongate, entire to sinuate-lobulate, rounded, obtuse or sub-acuminate, the sinuses rounded between the lobes, upper surface ± hairy to glabrous, lower surface very densely greyish-white tomentose, generally with ± straight prickles on the midrib at least beneath. Leaves solitary, the upper ones often appearing geminate or ternate; petiole (0.3)1–3 cm long; lamina membranous, 3–20 × 1. 5–13.5 cm, ovate to elliptic or oblong-lanceolate, sometimes obovate or ± circular, base sub-hastate or truncate, rounded to cuneate, and ± unequal-sided, apex acute to obtuse or acuminate, irregularly sinuate-lobed to divided, the lobes ± triangular to elongate, entire to sinuate-lobulate, rounded, obtuse or sub-acuminate, the sinuses rounded between the lobes, upper surface ± hairy to glabrous, lower surface very densely greyish-white tomentose, generally with ± straight prickles on the midrib at least beneath

Morphology Reproductive morphology Inflorescences

Cymes lateral, usually leaf-remote or occasionally leaf-opposed, at first sometimes appearing terminal, unbranched or occasionally forked, sub-umbelliform or racemiform, tomentose, usually sparingly armed, the prickles ± straight, 2–13-flowered, usually the lowest flower(s) larger and more prickly, sometimes all flowers unarmed, occasionally flowers solitary; peduncle none or very short; pedicels (5)8–15(23) mm long, slender but stouter in fertile flower(s), erect to recurved, leaving raised scars after abscission, in fruit elongated to 5 cm, strongly thickened distally and stout, ± recurved or deflexed. Cymes lateral, usually leaf-remote or occasionally leaf-opposed, at first sometimes appearing terminal, unbranched or occasionally forked, sub-umbelliform or racemiform, tomentose, usually sparingly armed, the prickles ± straight, 2–13-flowered, usually the lowest flower(s) larger and more prickly, sometimes all flowers unarmed, occasionally flowers solitary; peduncle none or very short; pedicels (5)8–15(23) mm long, slender but stouter in fertile flower(s), erect to recurved, leaving raised scars after abscission, in fruit elongated to 5 cm, strongly thickened distally and stout, ± recurved or deflexed

Morphology Reproductive morphology Flowers Calyx

Calyx (4)5-lobed or divided, greyish-white tomentose, ± prickly or unarmed, in fruit somewhat enlarged, very often more deeply divided, somewhat glabrescent, sparsely prickly; tube 2–4 mm long, ± campanulate; lobes 2–8 × 1.5–4 mm, triangular to ovate-elliptic or oblong, acute to long-acuminate, hairy mainly on the midrib to glabrous inside, in fruit rather leathery, to 10 × 5 mm, broadly lanceolate. Calyx (4)5-lobed or divided, greyish-white tomentose, ± prickly or unarmed, in fruit somewhat enlarged, very often more deeply divided, somewhat glabrescent, sparsely prickly; tube 2–4 mm long, ± campanulate; lobes 2–8 × 1. 5–4 mm, triangular to ovate-elliptic or oblong, acute to long-acuminate, hairy mainly on the midrib to glabrous inside, in fruit rather leathery, to 10 × 5 mm, broadly lanceolate

Morphology Reproductive morphology Flowers Corolla

Corolla violaceous to purple or pale mauve, yellowish or whitish, sometimes with purplish-brown markings, 1.3–3 cm across, ± rotate to stelliform; lobes 4–17 × 1.5–3.5 mm, narrowly ligulate, acute, involute at the margins, tomentose outside and hairy mainly on midrib to subglabrous inside. Corolla violaceous to purple or pale mauve, yellowish or whitish, sometimes with purplish-brown markings, 1. 3–3 cm across, ± rotate to stelliform; lobes 4–17 × 1. 5–3.5 mm, narrowly ligulate, acute, involute at the margins, tomentose outside and hairy mainly on midrib to subglabrous inside

Morphology Reproductive morphology Flowers Gynoecium Pistil

Ovary 1.5–3(5.5) × 1–3(5) mm, ± globose or ovoid, ± densely hairy, 2-locular; style 6–8(10) mm long, very much shorter in male flowers, straight, very shortly hairy in the lower half or tomentose to near the apex in male flowers.

IUCN Red List of Threatened Species https://www.iucnredlist.org/species/153946895/153946897

Conservation

LC - least concern

Extinction risk predictions for the world's flowering plants to support their conservation (2024). Bachman, S.P., Brown, M.J.M., Leão, T.C.C., Lughadha, E.N., Walker, B.E. https://nph.onlinelibrary.wiley.com/doi/full/10.1111/nph.19592

Conservation

Predicted extinction risk: not threatened. Confidence: confident

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

Type

Type: South Africa, Cape of Good Hope, near Morleg, Drège s.n. (G-DC, holo.; AD, BM!, K!, P!, possible iso.)

Morphology General Habit

Shrub or tree, 2–6 m, erect, usually armed; young stems densely stellate-pubescent, trichomes porrect and multangulate, white-translucent or yellowish, densely matted, sessile or stalked, stalks up to 2 mm, rays 8–12, 0.1–0.5 mm, midpoints shorter than rays or up to 1 mm; prickles straight becoming curved, 8–17 mm long, 3–10 mm wide at base, flattened, prominent

Morphology Leaves

Leaf blades drying strongly discolorous, red-green to yellow-green above, white-grey underneath, ovate, sometimes elliptic, 8–15 × 6–12 cm, 1.5–2 times longer than wide, base cordate to truncate(auriculate), usually equal, margin lobed, the broadly deltate lobes 2–3 on each side, 1.5–4.5 cm long, often with secondary lobing, apically obtuse (rounded), extending 1/4–3/4 of the distance to the midvein; apex acute; densely stellate-pubescent abaxially, trichomes on abaxial surface porrect, sessile or stalked, stalks to 0.1 mm, rays 8–12, 0.15–0.8 mm, midpoints same length as rays or up to 1 mm, adaxially glabrescent, the trichomes reduced; primary veins 3–6 pairs; petiole 1.2–3 cm, ± 1/6 of the leaf length

Morphology Reproductive morphology Inflorescences

Inflorescences rarely branched, 3–6 cm long, with 4–12 flowers; peduncle 0–35 mm long; rachis 0.5–2.5 cm long; peduncle and rachis unarmed; pedicels 1–3.5 cm long, in fruit 2.5–4.5 cm long, unarmed or with 1–5 prickles

Morphology Reproductive morphology Flowers

Flowers heterostylous, 5-merous, only the basal 1(–2) long-styled

Morphology Reproductive morphology Flowers Calyx

Calyx 3–15 mm long, lobes long-deltate to broadly deltate, 2–7 mm long, acute to apiculate, usually with 2–10 prickles in long-styled flowers

Morphology Reproductive morphology Flowers Corolla

Corolla white (mauve), 1.5–3.2 cm in diameter, lobed for 1/2–4/5 of its length, the lobes deltate or long-deltate, 6–15 × 2–5 mm

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens equal; anthers 4.5–6.5 mm

Morphology Reproductive morphology Flowers Gynoecium Ovary

Ovary stellatepubescent in the upper 1/5; style 7–10 mm long on long-styled flowers

Morphology Reproductive morphology Fruits

Berries 1(–3) per infructescence, evenly green when young, yellow at maturity, 3–5 × 2–4.5 cm, apically rounded to apiculate or acute; fruiting calyx usually unarmed

Morphology Reproductive morphology Seeds

Seeds 4–5 × 2.7–4 mm

Figures

Fig 24, p 199

Ecology

Forest margins, grassland, scrub, and disturbed open places; 1200–2500 m

Note

Solanum aculeastrum is a widespread and variable species found across the African highlands. It is easy to recognise by its markedly discolorous lobed leaves that are almost white below and by its prominent orange downwardly hooked prickles, although these are sometimes absent. The fruit is frequently compared to lemons: big, almost always single, yellow, round or apiculate or elongated, with a tendency to develop warts. Solanum aculeastrum is a distinctive species unlikely to be misidentified, except for possible confusion with the closely related S. phoxocarpum and S. thomsonii, which differ in fruit characters.

Distribution

Range: Nigeria, Cameroon, Congo-Kinshasa, Rwanda, Burundi, Sudan, Angola, Malawi, Mozambique, Zimbabwe, Swaziland, South Africa Flora districts: U2 U4 K3 K4 K5 K6 K7 T1 T2 T3 T6 T7