Solanum americanum Mill. - Black Nightshade

Solanum americanum plant

Family - Solanaceae

Stems - To 1m tall, erect, herbaceous but can be fairly stout, widely branching, green but often purplish in strong sun, from thickened roots, mostly glabrous but with some strigose hairs on the newest growth, terete or angled, minutely winged from decurrent petiole tissue. Wings to .5mm broad, scabrous from strigose hairs and their enlarged bases.

Solanum americanum stem

Leaves - Alternate, petiolate. Petioles to +/-4cm long, winged by decurrent blade tissue or not. Blades typically ovate, acute, with wavy margins or a few coarse teeth (the teeth with rounded apices), to +/-10cm long, +/-7cm broad, sparse strigose above and below, deep dull green above, light green below.

Solanum americanum leaves

Inflorescence - Loose pedunculate umbels or corymbs from the sides of the stem in the internodes. Peduncles to 3cm long, strigose, erect. Pedicels to 1cm long, strigose, spreading to erect in flower, nodding in fruit.

Solanum americanum inflorescence

Flowers - Corolla white, 5-lobed, 1cm broad, glabrous. Lobes lanceolate-triangular, 4-5mm long, +/-2mm broad. Corolla tube green, -2mm long, glabrous. Stamens 5, adnate at the apex of the corolla tube, erect, exserted. Filaments green, 1-1.3mm long, with some cilia on margins. Anthers yellow, 2mm long, converging around the style. Ovary superior, green, glabrous, ovoid, 1.2mm long in flower. Style green, glabrous in the apical half, hispidulous in the basal half, 3mm long. Stigma globose-capitate. Calyx tube green, 1mm long, antrorse strigose externally, glabrous internally, 5-lobed. Lobes 2-3mm long, somewhat unequal, 1-1.3mm broad, subacute at the apex, subulate to linear-oblong. Fruit a globose berry to +/-7mm in diameter, blackish when mature, shiny or not. Seeds many.

Solanum americanum flowers

Solanum americanum fruitsDeveloping fruits.

Flowering - May - November.

Habitat - Waste ground, disturbed sites, open woods, pastures, roadsides, railroads.

Origin - Native to U.S.

Other info. - This is a very common toxic plant. It is in the same family as the tomato and potato. The plant is very variable in size and also in leaf shape but the description above is generally very good for the species. The petals of the corolla are typically white but can have shades of blue or purple.
The name S. americanum is debated and S. ptycanthum Dun. ex DC. may be a better name. S. nigrum  var. virginicum L. is also used.

Photographs taken off Hwy 60, Carter County, MO., 7-19-03.


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