“Mustard tree” is a term often used to describe certain large mustard plants or, more specifically, the Arak tree (Salvadora persica). This term can be confusing, as it does not refer to a single botanical classification like typical trees. Instead, it encompasses plants known for their mustard-like properties or those that grow to a significant size, resembling small trees or large shrubs.
Native Habitats and Climate
Salvadora persica is native to arid and semi-arid zones across the Middle East, North Africa, and parts of India and South Asia. It is commonly found in desert floodplains, along riverbanks, within grassy savannahs, and in thorn shrubs, often indicating the presence of groundwater. This species tolerates extreme heat, enduring temperatures up to 45°C.
Brassica nigra, or black mustard, originated in Eurasia. Its native range extends across the Mediterranean region, central Europe, the Middle East, and the Ethiopian highlands. It typically prefers a Mediterranean-type climate, characterized by warm, dry summers and mild, wet winters. It can tolerate annual rainfall from 300 to 1700 millimeters and average temperatures between 6°C and 27°C.
Environmental Growing Conditions
Salvadora persica exhibits remarkable adaptability. It prefers sandy soil with excellent drainage but can flourish in poor, nutrient-deficient, saline, and alkaline soils. This species requires abundant sunlight, thriving in full sun with more than six hours of direct exposure daily. It is highly drought-tolerant, preferring dry conditions and requiring infrequent watering, typically every two to three weeks.
Brassica nigra requires somewhat different growing conditions. It thrives in moist, well-drained soil that has been amended, and it also requires full sun exposure. While adaptable to various soil types including sandy, loamy, and clay, it prefers well-drained conditions. This plant can tolerate a range of soil pH, from acid to neutral and alkaline. However, Brassica nigra does not perform well in hot weather, favoring cooler conditions for optimal growth.
Common Mustard Species and Their Distribution
Salvadora persica is an evergreen shrub or small tree generally reaching 6 to 7 meters, though some specimens can grow up to 10 meters tall. It is widely recognized by its common names like Arak tree, toothbrush tree, and miswak, particularly due to the traditional use of its twigs for oral hygiene. Its distribution extends across the Middle East, North Africa, and into India and other parts of South Asia, including the Arabian Peninsula.
Brassica nigra, commonly known as black mustard, is an annual plant typically growing between 0.6 and 2.5 meters tall, though it can sometimes reach up to 8 feet under favorable conditions. While cultivated globally for its seeds, which are used to make mustard condiment, it has also naturalized in many regions outside its native range, including parts of Australasia and the Americas, where it can sometimes become an invasive species.