Description:
Jaltomata Schlechtendal is a diverse neotropical genus of about 50 self-compatible species.  
Perennial herbs or shrubs usually to about 1 or 1.5 m high (-- 4 m when scandent without specialized structures); unarmed. 
Branches erect or spreading; 4- or 5-sided to terete; usually hollow. 
Vesture of multicellular finger- or dendritic-hairs, gland-tipped or not. 
Leaves alternate or appearing opposite (rarely appearing verticillate); simple; petiolate; estipulate; ovate, ovate-lanceolate or ovate-acuminate, sometimes basally truncate; entire, subentire or toothed; sometimes tapering asymmetrically along distal portion of petiole. The leaves of at least one species are deciduous!
Inflorescence umbel-like (Figure 1) or branced in a few species (Figure 2), axillary or from a stem dichotomy (false dichotomy), pedunculate (exceptions: J. andersonii has an unarticulated axis, by definition a peduncle though the peduncle may have been lost by reduction, joining the flower and the plant, and J. diversa lacks a peduncle: the umbel-like inflorescence is sessile). 
Pedicels basally articulated after fruit ripens; sometimes angled. 
Flowers five-merous; bisexual; regular, usually protogynous. 
Calyx enclosing the bud with valvate aestivation; sepals partially fused; lobes triangular, narrowly triangular or obtuse; rotate with a stellate outline, or the lobes reflexed. 
Fruiting calyx conspicuously accrescent; green or purple; spreading behind berry, rotate to reflexed. 
Corolla with five larger lobes alternating with 5 smaller lobules, the latter sometimes inconspicuous or absent. 
Corolla aestivation with five valvate lobes, each lobe alternating with an inwardly pleated and shorter lobule. 
Corolla 1 - 6 cm in diameter; rotate, broadly infundibular, campanulate, tubular, or the tube urceolate and the limb revolute; if the corolla is non-rotate then the lobes flare.
Radial corolla thickenings - radially oriented thickenings of the corolla that extend from the base of the stamen toward the lobule, and create at the base of the flower a cavity (between each pair of thickenings) that holds nectar. In the photo above the green radially oriented lines in the base of the corolla are the radial corolla thickenings. Many but not all Andean species have radial corolla thickenings.
Filaments 5; filiform; markedly enlarged/ swollen at base where adnate to base of corolla. The filaments insert on the ventral face of the anther, meaning that the distal end of the filament (where it meets the anther) is visible on the ventral side and is not visible at all on the dorsal side of the anther. The expanded base of the filament is usually pubescent with finger hairs. The slender part of the filament is often but is not always pubescent with finger hairs.
Anthers dehiscing longitudinally, to 5 mm long. 
Ovary superior; bicarpellate (rarely tricarpellate in J. auriculata, and J. repandidentata I grew, see Murray, 1945); ovules 42 to over 400 per ovary. 

Style slender (except for the styles of J. aspera and J. greenFruitOrgangeNectar); exserted or not. 
Stigma single; bilobed, slightly bilobed, or grooved; self-compatible in the species that have been studied.
 
Nectar is clear and in produced in small volume, or in contrast it may be orange to red, and in much greater volume, filling base of corolla and sometimes visible through corolla.  Orange to red nectar is known only from a subset of the Peruvian and Bolivian species. Nectar pools on the base of the corolla and around the base of the androecium in all species except two: the two exceptions have a bowl-shaped ring of tissue formed by the base of the androecium (J. aspera and J. greenFruitOrangeNectar) and nectar pools on this bowl-shaped ring of tissue in these species (it does not pool on corolla tissue). The nectar is presumably produced by the nectary disk, an annular disk around the base of ovary. 

Fruit a juicy globose or oblate berry; 4 - 25 mm in diameter; many-seeded; black/purple, green, orange, red or nearly white.   The berries of at least one species split open at maturity (J. chotanae)!

Similar Genera

     Jaltomata differs from Physalis by the former having a fruiting calyx that does not enclose the berry, while the fruiting calyx of Physalis encloses the berry.  Jaltomata differs from Solanum by the former having longitudinal anther dehiscence and an ovarian nectar disk producing nectar, while Solanum has anthers with terminal pores and no ovarian disk nor nectar.  Jaltomata differs from Cuatresia by the former having basal pedicel articulation while the latter lacks pedicel articulation (Hunziker, 1987).

Habitat:

I have collected Jaltomata species most commonly along roadsides where the native vegetation is still present to some extent. If the native vegetation has been entirely eliminated for agriculture I usually can't find Jaltomata. In other words, most species are tolerant of a considerable amount of open sun, but not completely open sun. However, J. nigricolor and J. salpoensis are found in completely open sun, with no shade whatsoever. In the Andes, rock walls and steep roadside embankments are common habitats of Jaltomata species. The easiest way to find J. repandidentata is in coffee plantations that have not been weeded (Mexico to Bolivia), the coffee plants providing considerable shade. Even in the forest, when I have found Jaltomata it was along a trail or gravel road (Costa Rica) where light was entering through the canopy at least part of the day. In Mexico, the easiest way to find J. procumbens is in corn fields that have not been weeded, the corn plants usually providing shade depending on the height of the corn. Some Jaltomata species do not stand alone, and require other plants to grown among (J. dendroidea and J. pallascana, for example); here the physical support of other plants and the shade of other plants are inseparable. One species grows, with few exceptions, in between or very near the spiny leaves of Puya.

Most Jaltomata species are somewhere in the middle of the spectrum of dry to moist habitats. On the wet end of the spectrum there are ecotypes of J. procumbens that reside in the rainforest, for example I have seen them in Costa Rica at high elevation, including an epiphyte at Monteverde. As well, J. werffii grows on wet slopes (Galápagos Islands). On the dry end of the spectrum are the species that reside in the lomas. And the not yet named species having both green fruits and red/orange nectar dies back to the ground for several months of the year; its habitat is seasonally dry. One of the lomas species has deciduous leaves, and it may receive no rainfall for months, and then when the fog returns, approximately in August, the leaves emerge again.

Geographic Distribution:

The approximately 50 species of Jaltomata are distributed from southeastern Arizona, USA (Kearney and Peebles, 1951) to southern Bolivia (Morton, 1944), on three of the Galápagos Islands (D'Arcy, 1982), and on the Greater Antilles (Cuba, Jamaica, Haiti, Dominican Republic, Puerto Rico; Adams, 1972; Davis and Bye, 1982; Liogier and Martorell, 1982). The majority of the species are Andean but one of the most common species, J. repandidentata, extends throughout much of the continental range of the genus, from Mexico to Bolivia (Mione and Yacher, 2005).

Highest Collection: J. yungayensis at 4,150 m of elevation (J. Mostacero L, S. Leiva G. et al. 1897)

In the department of Cajamarca, Peru, there are over 20 distinct and defendable species! Link to Jaltomata of Cajamarca.

In the department of La Libertad, Peru there are about 15 species!

Link to Jaltomata of Arizona, Mexico and Central America