The rooibos plant, scientifically known as Aspalathus linearis, is a shrub in the Fabaceae (legume or pea) family. It is the source of rooibos tea, a widely consumed herbal infusion known for its characteristic flavor and aroma.
The Rooibos Plant’s Native Habitat
The Aspalathus linearis plant is an erect to spreading shrub, typically reaching heights of 0.5 to 2 meters. It features slender, needle-like green leaves, usually between 15-60 mm long and up to 1 mm thick, and produces small yellow flowers in spring to early summer. Its young branches often display a reddish hue. The plant’s roots can extend two meters or more underground, enabling it to access water in its arid environment.
This plant thrives exclusively in the Cederberg mountains of South Africa, part of the Western Cape province, making it an endemic species. The area’s unique conditions, characterized by sandy, acidic soils rich in minerals and a Mediterranean climate with dry, hot summers and mild, wet winters, are particularly suited for its growth. Attempts to cultivate rooibos commercially outside this limited geographical range have largely been unsuccessful, underscoring the plant’s sensitivity to its precise environmental requirements.
Harvesting and Processing Methods
Rooibos is harvested once a year, primarily from January to April, when branches contain a high concentration of essential oils. Harvesters cut mature branches by hand, ensuring the plant’s ecosystem remains undisturbed. Bundled branches are then transported to processing facilities.
At the facility, branches are cut into small, uniform pieces (1.5mm to 5mm). The cut material is then bruised (often by a tractor) to activate enzymes and initiate oxidation. For red rooibos, this material is moistened and laid out in heaps for 10-14 hours (often overnight) to undergo enzymatic oxidation, also called fermentation. This transforms the green material into its characteristic reddish-brown color, developing sweet, earthy, and sometimes caramel or honey notes.
Green rooibos, in contrast, skips the oxidation step. After cutting, it is immediately heated (e.g., blanching or machine-drying) to halt enzymatic activity and preserve its natural green color. This results in a lighter liquor color and a milder, more vegetal or grassy flavor with subtle sweet notes.
Notable Compounds and Qualities
Rooibos contains no caffeine, unlike traditional Camellia sinensis teas. This makes it suitable for those sensitive to caffeine, including children and pregnant individuals. It also has low tannin levels, contributing to a less bitter taste than many black or green teas. Low tannin content also means it does not significantly interfere with iron absorption.
Rooibos’s chemical composition includes various polyphenols, such as flavanols, flavones, flavanones, and dihydrochalcones. Aspalathin and nothofagin are two unique phenolic compounds found specifically in rooibos. These compounds contribute to its antioxidant activity, helping counteract reactive oxygen species in the body. Fresh rooibos leaves also contain ascorbic acid (vitamin C).