A key to the tomato species was formulated by C.M. Rick and issued in Tomato Genetics Cooperative Reports 27:21. In the meanwhile we have had much experience in the use of this key and its application to new accessions. The following key encompasses changes and simplifications that accommodate all accessions known to us and to correct errors in the first attempt.
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 Mill.
1.1.2. Fruit diameter 1.5-2.5 cm; 2-loculed.
L. esculentum var. cerasiforme (Dun.) Gray
1.2. Fruit diameter less than 1.5 cm, usually ca. 1 cm;
leaf margin generally undulate or entire.
L. pipinellifolium (Jusl.) Mill.
2. Interior of fruit yellow or orange; seeds 1.0 mm or shorter
L. cheesmanii Riley
3. Interior of ripe fruit green or whitish; seeds of
varying sizes.
3.1. Sympodia with 3 leaves. L. hirsutum Humb. and Bonpl.
3.2. Sympodia with 2 leaves.
3.2.1. Inflorescences with small or no bracts.
(subgeneric "minutum" complex)
a. Flowers small (corolla diameter 1.5 cm or less);
seeds 1 mm or shorter.
L. parviflorum Rick, Kesicki, Fobes, and Holle
b. Flowers larger (corolla diameter 2 cm or more); seeds
1.5 mm or longer.
L. chmielewskii, Rick, Kesicki, Fobes, and Holle
3.2.2. Inflorescences with large bracts.
a. Anthers attached in a tube, dehiscent by lateral
apertures.(subgeneric peruvianum complex)
i. Plants erect; peduncle longer than 15 cm; flowers
congested;anther tube straight.
L. chilense Dun.
ii. Plants spreading: peduncle shorter than 15 cm;
flowers moreloosely arrayed; anther tube
generallybend distally. L. peruvianum (L.) Mill.
b. Anthers free, poricidal.
L. pennellii (Corr.) D'Arcy (formerly
Solanum pennelliiCorr.)