Solanum pennellii is a dryland-adapted species of wild tomato that’s native to the western slope of the Andes in Peru. In this habitat, the tomato gets much of its water from fog; therefore, the method of watering I’ve had the most success with is misting the leaves with water. The root system is small and tentative, and the plants easily succumb to overwatering.
Solanum pennellii produces very small, green-colored, fuzzy fruits. The flavor is unappealing, even when fully ripe. Perhaps the fuzz of the fruits provides protection against sunscald and/or predators. The seeds are very tiny, and they easily succumb to damping off.
In most of its range, Solanum pennellii is self-sterile, meaning it cannot pollinate itself and requires pollen from a plant that is not closely related. Therefore, the flowers are large and colorful in order to attract pollinators. At the edges of this species’ range, some populations are capable of self-fertilization and tend to have smaller, less colorful flowers.
The flowers of Solanum pennellii are unique among wild tomatoes: Instead of having an “anther cone,” they have an “anther cylinder.” Also, pollen is shed from a pore in the tip of the anther instead of along the length of the anther. Solanum pennellii is most closely related to Solanum habrochaites, and both species can act as pollen donors to domestic tomatoes but cannot be pollinated by domestic tomatoes. Solanum habrochaites and Solanum pennellii can pollinate each other.
Solanum pennellii foliage has roundish leaflets that are distinct among the wild tomato species. These leaflets are strongly conserved in interspecies hybrids. The foliage of Solanum pennellii can be very aromatic. The aromas can be carried into the smell and taste of crosses with domestic tomatoes. The offspring of the crosses may be sweet and aromatic and have high umami.
On my farm, I am growing Solanum pennellii as a pollen donor to make hybrids with domestic tomatoes in order to move the self-sterile trait into a population of large-flowered, large-fruited, sweet, aromatic, tasty tomatoes.
Joseph Lofthouse
World Tomato Society Ambassador
The Beautifully Promiscuous and Tasty Tomato Project