Tomato Genetics Resource Center

A revised key for the Lycopersicon and related Solanum species

The following key is a revision to that formulated by Rick et al. (1990) and published in the Tomato Genetics Cooperative Report, 40: 31. The key has been expanded to add subspecific taxa, as well as the tomato-like nightshades.

(Species links bring up images of selected taxon, these pages make use of web browser pop-ups, thus you may need to enable "popups")					Equivalent name in Solanum (see links below)
1. Interior of ripe fruit red: seeds 1.5 mm or longer.
	1.1. Fruit diameter more than 1.5 cm; leaf margin generally serrate.
		1.1.1. Fruit diameter 3 cm or larger, 2-to-many loculed. ...L. esculentum			Solanum lycopersicum
		1.1.2. Fruit diameter 1.5-2.5 cm; 2-loculed. ...L. esculentum var. cerasiforme
	1.2. Fruit diameter less than 1.5 cm, usually ca. 1 cm; leaf margin generally undulate or entire. ...L. pimpinellifolium				Solanum pimpinellifolium.
2. Interior of fruit yellow or orange; seeds 1.0 mm or shorter ...L. cheesmanii Riley					Solanum cheesmaniae
	2.1. Leaves highly subdivided, internodes short, densely pubescent, large accresant calyx...L. cheesmanii f. minor				Solanum galapagense
3. Interior of ripe fruit green or whitish; seeds of varying sizes.
	3.1. Sympodia with 2 leaves.
		3.1.1. Inflorescences with small or no bracts. (subgeneric "minutum" complex)
			3.1.1.1. Flowers small (corolla diameter 1.5 cm or less); seeds 1 mm or shorter. ...L. parviflorum		Solanum neorickii
			3.1.1.2. Flowers larger (corolla diameter 2 cm or more); seeds 1.5 mm or longer. ...L. chmielewskii		Solanum chmielewskii
		3.1.2. Inflorescences with large bracts.
			3.1.2.1. Anthers attached in a tube, dehiscent by lateral apertures. (subgeneric "peruvianum" complex)
				3.1.2.1.1. Plants erect; peduncle longer than 15 cm; flowers congested;anther tube straight. ...L. chilense	Solanum chilense
				3.1.2.1.2. Plants spreading: peduncle shorter than 15 cm; flowers more loosely arrayed; anther tube generally bent distally. ...L. peruvianum	Solanum peruvianum
			3.1.2.2. Anthers free, poricidal. ...L. pennellii		Solanum pennellii
				3.1.2.2.1. Leaves and stems puberulous, shiny. ... L. pennellii var. puberulum
	3.2. Sympodia with 3 leaves. ...L. hirsutum				Solanum habrochaites
		3.2.1. Leaves and stems nearly free of hairs, stems slender, darkly pigmented with anthocyanins ...L. hirsutum f. glabratum
	3.3. Sympodia with more than 3 leaves.
		3.3.1. Anthers white to cream-colored, leaf margins dissected
			3.3.1.1. Leaves and stems pubescent, fruit purplish green, ‹ 1 cm diameter, ripen to berry texture. ...S. lycopersicoides		Solanum lycopersicoides
			3.3.1.2. Leaves and stems glabrous, nearly succulent, fruit yellowish green, usually, ›1 cm diameter, ripen to a papery texture. ...S. sitiens		Solanum sitiens
		3.3.2. Anthers yellow, leaf margins entire, leaflets elliptic to lanceolate
			3.3.2.1. Leaflets relatively broad, scabrous above, generally 2 pairs of lateral leaflets, fruits 2-3 cm. ....S. juglandifolium		Solanum juglandifolium
			3.3.2.2. Leaflets relatively narrow, smooth-velvety above, fruit large, mostly multilocular. ...S. ochranthum		Solanum ochranthum