Capsicum chacoense

Overview

Capsicum chacoense is a naturally occurring pepper species from the Gran Chaco, a vast region of dry and seasonally humid forests spreading across parts of Bolivia, Paraguay and Argentina. It is a wild species, not a cultivar of the common garden chilli.

The plant tends to remain smaller and more intricately branched than many cultivated peppers. It makes small, plain white flowers and numerous berries that typically turn orange to bright red. Its combination of a sturdy basal rootstock, angled stems and tiny, often fiery fruit gives it a distinctive appearance.

Native countries

Bolivia, Paraguay, Argentina

Scientific name

Capsicum chacoense Hunz.

First described

1950

Growth habit

Wild shrub or subshrub

Ripe fruit

Orange to bright red

Typical height

40 cm–1 m; sometimes taller

Discovery & scientific naming

Argentine botanist Armando T. Hunziker formally published the name Capsicum chacoense in Darwiniana in 1950. The name refers to the Chaco, the South American region where the species is so strongly associated with the local vegetation.

Its scientific history reaches further back than the publication date. The specimen selected as the species' lectotype was collected by Hunziker on 12 March 1945 between Colonia Benítez and Resistencia, in Argentina's Chaco Province. The 2022 monograph reviewed those original collections and clarified their botanical identity.

Hunziker also named a densely hairy form, C. chacoense var. tomentosum. Modern treatments, including Kew's Plants of the World Online, place that name within C. chacoense, recognising that hairiness varies naturally within the species.

Plant & foliage

The plant is usually a densely branched shrub 40–100 centimetres tall, although some specimens reach about 2.5 metres. Branches spread outward from a thickened rootstock and often form a recognisable zigzag pattern. Young green or purple-tinged stems are sharply angled; older branches develop brown bark.

The leaves are generally ovate to narrowly ovate, with pointed tips and smooth margins. Typical blades measure 2–6 cm long, though larger leaves occur. The foliage ranges from nearly hairless to noticeably hairy. Some populations in northeastern Argentina and Paraguay are particularly densely covered in fine hairs.

Flowers

Flowers appear singly near the leaf axils on slender, angled stalks. Their petals form a small, five-pointed star that is entirely white, without the green or yellow spots seen in some relatives. The open flower is usually only 9–11 mm across, with pale filaments and yellowish or cream anthers.

Behind each flower is a short green calyx bearing several little projections, commonly five longer points alternating with up to five shorter ones. These subtle details help botanists separate C. chacoense from lookalike wild peppers.

Fruit & seeds

The berries are tiny by cultivated-pepper standards. They may be rounded, about 7–10 mm across, or somewhat elongated, reaching approximately 8–14 mm long. Immature fruit is green and may show dark markings before developing orange and eventually bright-red colour. Mature berries are held on upright stalks and detach readily.

The 2022 botanical monograph records 14–25 pale-yellow seeds per fruit. Most wild populations produce pungent berries, but naturally non-pungent plants are also documented. This is a feature of the wild species itself, not necessarily the result of modern breeding.

Small size does not mean mild flavour. Where pungency is present, the berries are valued locally for their concentrated heat and flavour. Their heat varies from plant to plant, so a single Scoville figure would be misleading for the entire species.

Habitat & native range

Capsicum chacoense is found across the Gran Chaco region of Bolivia, Paraguay and northern to central Argentina. It grows in dry and subhumid Chaco forests, including lower woodland and the drier inter-Andean valleys. Published collections span roughly 50–2,700 metres above sea level.

In natural settings the plants are commonly found in the undergrowth, sheltered beneath other shrubs or trees rather than standing fully exposed. Their strongly branched structure and substantial basal rootstock are part of the species' characteristic form in these seasonal environments.

For plants observed in the southern hemisphere, the botanical monograph records flowering mainly from late October through March or April, followed by fruiting from January through May or June. Local seasons, altitude and climate affect the timing.

Why some wild fruit is hot — and some is not

One of the most important scientific discoveries involving Capsicum chacoense is that pungent and non-pungent individuals can grow side by side in the same wild population. Researchers studying wild peppers in Bolivia found that the proportion of hot-fruited plants changed markedly between sites.

A 2008 study led by Joshua Tewksbury, published in Proceedings of the National Academy of Sciences, examined why this variation persists. The researchers showed that capsaicinoids — the compounds responsible for chilli heat — can help protect wild fruits and seeds against fungal pathogens, including Fusarium.

That makes the heat of a wild pepper more than a human culinary preference. In some habitats, producing capsaicinoids can help seeds survive microbial attack. The balance of ecological pressures differs across locations, helping explain why plants that are hot and plants that are not can coexist.

Read the original research: Tewksbury et al. (2008), Evolutionary ecology of pungency in wild chilies.

Local names & traditional uses

This species has been part of local food traditions long before it had a formal scientific name. The small berries are gathered as hot condiments, and the 2022 monograph records them being sold fresh or preserved in oil or vinegar at regional markets. It also documents traditional medicinal uses.

The names vary by country and community. Regional Spanish names include ají cumbarí, cumbarí, ají del monte and picante del monte. The monograph additionally records distinct Indigenous names, including kodae among Pilagá speakers and pájanak among Chorote speakers in Argentina. These names reflect knowledge and use rooted in particular communities, rather than a single universal name for the pepper.

Even though cultivated chilli varieties dominate international trade, wild peppers such as C. chacoense remain relevant to local food culture and to researchers studying diversity in the genus.

Its place among wild peppers

Genetic research places Capsicum chacoense within the broader Baccatum group of the genus, but it remains a distinct species from the cultivated Capsicum baccatum. Both can produce small red fruits in wild forms, which has contributed to confusion in herbarium specimens.

Botanists distinguish C. chacoense by its small, completely white flowers, characteristic calyx points, densely branched growth and variations in stem and leaf hairs. It has 24 chromosomes (2n = 24), a number shared by several other Capsicum species.

The formerly described hairy variety, C. chacoense var. tomentosum, is currently treated by Kew as a synonym within the species, not a separate accepted species.

Conservation

Unlike some highly restricted wild peppers, C. chacoense has a large recorded distribution across the Gran Chaco. The 2022 Capsicum monograph assessed it as Least Concern in a preliminary species-level conservation assessment.

That assessment refers to the species as a whole; it does not imply that every local Chaco population or its habitat is secure. Conserving wild populations matters because they preserve genetic variation, including the striking natural differences in pungency that have made this pepper so useful in evolutionary research.