Capsicum rhomboideum

Capsicum rhomboideum is a wild Andean clade species with a broad native range from Mexico through Central America into northern South America. It was first published in 1816 as Witheringia rhomboidea and is now accepted as Capsicum rhomboideum. A major identity point with this species is that it was long circulated under other names, especially Capsicum ciliatum, but current taxonomic treatment accepts Capsicum rhomboideum as the correct name. It is one of the most widespread and polymorphic wild Capsicum species and has the largest synonymy in the wild group.

It grows as an erect, slender, sprawling shrub and can also become a small tree, usually about 2.0 to 3.0 m tall and sometimes reaching 5.0 m. Older stems develop dark brown to brownish-purple bark with abundant pale lenticels. The leaves are borne in unequal pairs and are green, darker and slightly glossy above and lighter beneath. Major leaves are usually about 5.0 to 12.0 cm long and 2.0 to 5.0 cm wide, with shapes ranging from ovate to elliptic to rhomboid-ovate. The plant is variable in pubescence, but a mix of simple and branched hairs is characteristic.

Its inflorescences are usually axillary and commonly carry 3 to 8 flowers per node, sometimes up to 13. The flowers hang on straight, non-geniculate pedicels and have yellow campanulate to campanulate-rotate corollas about 6 to 10 mm long and 1.0 to 1.2 cm across. The calyx is cup-shaped with usually 5 appendages, and the combination of many-flowered inflorescences, yellow corollas, and pendent flowers is one of the clearest ways the species is recognised in the field. Flowering and fruiting can occur throughout the year.

The fruit is a small globose to slightly depressed berry about 5 to 9 mm across. It begins green and ripens bright red, later turning dark burgundy at full maturity. The fruit is non-pungent, with a thick opaque pericarp and no giant cells in the mesocarp. Each berry usually contains 24 to 60 dark brown seeds about 2.4 to 2.8 mm long. The small red to burgundy fruit, dark seeds, yellow flowers, and woody shrub to small-tree habit give Capsicum rhomboideum a very distinct identity.

This species is most often found in xerophytic thickets, dry forests, and tropical deciduous forest from about 250 to 2500 m, sometimes to 3000 m. It is also recorded for food and medicinal use. In Ecuador, long stems have been used to make drum hoops, and the species is recorded under several local names including arrayán, caspi morocho, hierba dura, hierba mora, siete varas, mora silvestre, veranera silvestre, arito de niña, cachimbito, and the Tzeltal indigenous name Tumaltez in Mexico.