NIGHT SHADE FAMILY
SOLANACEAE
Solanum is a genus of herbaceous plants There are many nightshades that are economically significant including S. melongena (eggplant), S. tuberosum (potato), S. scabrum (garden huckleberry), and S. lycopersicum (tomato). There are over a hundred species of Solanum growing in North America today. Many of the species in North America today are introduced and several rarely exist outside of cultivation.
Page 1 Seeds of wild nightshades tend to be less than 3.0 mm in diameter and flat to slightly concave. They have surface reticulation that varies among species. Seed shape is often oval or broadly elliptic, with some variation. Seeds vary in color from white to brown. The variability in morphology and size within a species and even among seeds within the same berry can make species identification difficult.
Carolina horse nettle, horse-nettle, or bull-nettle (S. carolinense) has a length range of 1.9 to 2.8 mm, width ranges from 1.4 to 2.1 mm, and thickness varies between 0.6 and 0.8 mm. The seed profile in broad view is variable in morphology but roughly ovate. The seed is compressed in cross section, with irregular thickness. The hilum notch is about 1.0 mm long, running along the ventral edge. Surface reticulation is an alveolate pattern.
Solanum nigrum compared to Solanum carolinense
Black nightshade (S. ptychanthum) is a taxon of some confusion. It is morphologically closely related to two other species, both also called black nightshade S. americanum and S. nigrum. Often the three species are clumped under the one taxon S. nigrum. Great Plains Flora Association clumps both species into the taxon S. ptycanthum (accurately spelled ptychanthum); they also note that other closely related species, including S. interius and S. scabrum, are part of, what they refer to as “the taxonomically difficult S. nigrum complex”. However, both the USDA’s National Plants Database and the Integrated Taxonomic Information System recognize all three species as separate, but note common overlaps in identification.
Due to the similarity in these species, for the purposes of seed morphology description they will be treated here as one. Seed length range is between 1.7 and 2.1 mm, width range is 1.4 – 1.6 mm, and thickness range is 0.6 – 0.7 mm. Seed profile in broad view is asymmetrically obovate with a blunt radicle tip at one end. In cross section the seed is irregularly elliptical. The hilum is located just below the radicle and is not well defined. The surface appears finely punctuate (minute holes) and at low magnifications may even look smooth; however, at higher magnifications the characteristic reticulation of the black nightshades is finely areolate (covered with shallow holes).
S. ptychanthum, S. americanum, and S. nigrum (the black nightshades) morphologically are very similar and, as mentioned above, are often clumped under one taxon. Those who see S. ptychanthum and S. nigrum as separate species see these as invasive species from Eurasia, while S. americanum is native to the American west and mid-west. The fruits and seeds of S. nigrum are slightly larger and thicker than their indigenous American relative S. americanum.
Nightshades can be poisonous due to their solanine content so it is vital to know the very cultivar or species that one is dealing with before consuming any part of it whether cooked or raw.
Solanum americanum Mill. American Nightshade (Black, Glossy, Small-flower Nightshade) Hilum is wide and extended beyond margin. Surface texture reticulum is shallow and well organized, especially near the margin. The seed has a fine reticulum and the hilum protrudes out beyond the margin. The seed is very similar to Solanum nigrum.
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Page 3 Solanum cardiophyllum Lindl. Heart-Leaf Nightshade
Solanum carolinense L. Ball Nightshade (Bull Nettle, Carolina Horsenettle) Surface texture is faintly reticulated and leathery. Hilum is large and thin and only slightly indents the margin. The seed does not have a sugary appearance and has a smooth texture.
Page 4 Solanum chenopodioides Lam. Tall Nightshade (Velvety, Whitetip Nightshade)
Solanum citrullifolium A. Braun Melon-leaf Nightshade
Solanum dimidiatum Raf. Torrey’s Nightshade (Robust Horsenettle)
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Solanum dulcamara L. Bitter Nightshade (Bittersweet, Climbing, Woody Nightshade) Surface texture is coarse reticulated. The seed is somewhat elongate and the hilum point extends well beyond the margin.
Page 6 Solanum elaeagnifolium Cav. Silverleaf Nightshade (Silver Nightshade) Hilum is a wide, gaping oval opening on the narrow edge. Surface texture is faintly reticulated and leathery. The seed has similar characteristics as Solanum carolinense (Horse-nettle) except these are larger. This seed tends to have a twist in its entire structure with an irregular round shape.
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Solanum interius Rydb. Plains Black Nightshade (Inland Nightshade) Surface texture is finely reticulate. The seed is light colored. The hilum protrudes outside the margin.
Page 8 Solanum lanceolatum Cav. Lance-leaf Nightshade
Solanum lasiocarpum Dunal. Indian Nightshade
Solanum linnaeanum Hepper & P.-M.L. Jaeger Black-spine Nightshade
Page 9 Solanum marginatum L. f. Purple African Nightshade (White-edge, White-margin Nightshade)
Solanum nigrescens M. Martens & Galeotti Divine Nightshade
Page 10 Solanum nigrum L. Black Nightshade (Blackberry, Common Nightshade) Surface texture has a strong reticulum. The hilum extends beyond the margin and is flattened as if pinched together.
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Page 12 Solanum physalifolium Rusby Argentina Nightshade (Green, Hairy Nightshade) Solanum physalifolium Rusby var. nitidibaccatum (Bitter) Edmonds Hilum is slightly protruding from margin. Surface texture is fine reticulated. Bases within the reticulations are shiny.
Solanum ptychanthum Dunal Black Nightshade (Eastern Black Nightshade) Hilum extends beyond margin. Surface texture is strongly reticulated. The seed is very light colored and small.
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Page 14 Solanum rostratum Dunal Horned Nightshade (Pincushion, Prickly, Spiny Nightshade, Buffalo Bur) Margin opposite hilum is moderately wavy but laterally square. Surface texture is deeply reticulate and irregular. The seed has a margin that is moderately square in cross section. The hilum is indented into the margin.
Page 15 Solanum sarrachoides Sendtn. Hairy Nightshade
(As the common name of S. physalifolium is the same “Hairy Nightshade”, there is much confusion in North America over these two species of Solanum.) Seeds are pale yellowish to tan and flattened.
Page 16 Solanum sisymbriifolium Lam. Sticky Nightshade (Viscid Nightshade, Wild Tomato)
Solanum tampicense Dunal Wetland Nightshade Hilum lobe often very extended. Surface texture is reticulate. Shape often modified by an exaggerated hilum margin.
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Solanum torvum Sw. Turkey berry Hilum is on or below margin line. Surface reticulation is weak to strong. The seed characteristics are variable. The reticulum is present but at various intensities. Seed colour is from light brown dark.
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Solanum triflorum Nutt. Cut-leaf Nightshade (Small, Three-flower Nightshade) Hilum extends from one end of the oval. Surface texture is stippled. The bases of the stipples are not uniformly shiny.
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Page 20 Solanum umbelliferum Eschsch. Bluewitch Nightshade
Solanum viarum Dunal. Tropical Nightshade (Tropical Soda-apple) Hilum is a slight indentation on margin. Surface Texture is very fine reticulum with very small interspaces. The seed has a hilum that is below or on the margin line. Page 21
Page 22 Solanum villosum Mill. Red Nightshade (Red-fruit, Woolly Nightshade)
Solanum virginianum L. Yellow-fruit Nightshade Page 23 Solanum xanti A. Gray Purple Nightshade
Solanum laxum Spreng. Jasmine Nightshade (Potato Vine) Solanum mauritianum Scop. Ear-leaf Nightshade Solanum opacum A. Braun & C. D. Bouche Green-berry Nightshade Solanum petrophilum F. Muell. Rock Nightshade Solanum prinophyllum Dunal Forest Nightshade Solanum robustum H. L. Wendl. Silverleaf Nightshade (Shrubby Nightshade) Page 24 Solanum seaforthianum Andrews Black Nightshade (Brazilian, Climbing, Deadly Nightshade) Solanum sturtianum F. Muell. Thargomindah Nightshade Solanum triquetrum Cav. Texas Nightshade Solanum wendlandii Hook. f. Costa Rican Nightshade (Potato Vine)
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