Spiny amaranth
Amaranthus spinosus L.
Spiny amaranth (Amaranthus spinosus) is an amaranth-family herb 0.3–1 m tall with a pair of sharp spines at each leaf axil; a pantropical weed whose young shoots are eaten and used as medicine.
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Gallery
Spiny amaranth — armed plant (spines at leaf axils)Spiny amaranth — whole plant (botanical garden)
Spiny amaranth — wild habit (whole plant)
Spiny amaranth — flower clusters
Spiny amaranth — flowers (detail)
Spiny amaranth — spines and seedsSpiny amaranth — armed plant (spines at leaf axils)Spiny amaranth — whole plant (botanical garden)Overview
Spiny amaranth (Amaranthus spinosus), also called spiny pigweed, is an annual herb of the amaranth family (Amaranthaceae), genus Amaranthus, 0.3–1 m tall (sometimes to 1.5 m) with an erect, branched, green-to-reddish stem. Its **most distinctive trait is a pair of sharp spines** (modified bracts) in each leaf axil, 0.5–1.5 cm long. The leaves are alternate, ovate-rhombic to lanceolate, 3–10 cm long, with entire margins and long stalks. The flowers are small and green, unisexual, borne in dense axillary clusters and in elongated terminal spikes; the plant bears both male and female flowers (monoecious). The fruit is a circumscissile utricle holding a single seed; the seeds are black, shiny and lens-shaped, about 1 mm across.
Updated by lebachungtdh@gmail.com · 10/12/2026
Spiny amaranth is native to tropical America and has spread as a weed throughout the tropics and subtropics, growing in waste ground, roadsides and fields. It likes sun and moist soil. Its **young leaves and shoots** are cooked and eaten as a leafy vegetable in parts of Asia and Africa, and it is also used in folk medicine and as fodder. Note the **sharp spines** and possible **oxalate/nitrate** content. It has not been assessed by the IUCN and is therefore listed as Not Evaluated (NE).
Updated by lebachungtdh@gmail.com · 10/12/2026
Life cycle
From seed to productGermination & seedling
Black seeds germinate on moist soil and grow into a soft seedling that quickly shoots up.
Stem, leaf & spine growth
The stem branches and forms **a pair of sharp spines** at each leaf axil — the species' key trait.
Flowering
Small green flowers form dense axillary clusters and terminal spikes; the plant is monoecious (both sexes).
Fruit & seeds
A circumscissile utricle holds one shiny black seed; the seed drops to the soil and the cycle continues.
Distribution & origin
Share of recorded occurrences by region- Tropical America (native)35%
- Southeast Asia (introduced)20%
- South Asia (introduced)15%
- Africa (introduced)15%
- Elsewhere (introduced)15%
Chemical composition
Relative content in agarwood resin- WaterMain component of the young shoots30%
- Dietary fibreAbundant in stems and leaves20%
- ProteinA leafy vegetable rich in plant protein15%
- Vitamins & mineralsVitamins A, C, iron and calcium15%
- Flavonoids & tanninsContribute to folk medicinal effects10%
- Oxalates & nitratesCaution when eaten raw or in large amounts10%
Uses
- Culinary: the **young shoots and leaves** are cooked and eaten as a leafy vegetable in many tropical countries.
- Folk medicine: the **whole plant** is used in some traditional remedies (per folk use).
- Fodder: the **stems and leaves** are fed to livestock and poultry.
- Caution: the plant bears **sharp spines** and may accumulate nitrates/oxalates — wear gloves and cook before eating.
- Name origin: **spiny amaranth** highlights the sharp spines; it is a wild, weedy amaranth.
Properties
- Morphology
- Erect branched stem with **spines at the leaf axils**
- Ecology
- A fast-growing sun-loving weed of open ground
- Culinary
- Young shoots edible when cooked
- Medicinal & other
- Used in folk medicine; also fodder
Habitat & conservation
Spiny amaranth prefers sunlight and moist soil, often growing wild on open ground, roadsides, pastures, farmland and waste places throughout the tropics and subtropics. Native to tropical America, it has spread widely as a familiar weed.
Conservation
Spiny amaranth is a common weed, not threatened, and often regarded as a weed to be controlled; it has not been assessed by the IUCN and is therefore listed as Not Evaluated (NE). Family Amaranthaceae, genus Amaranthus. Value: leafy vegetable, folk medicine and fodder.
References
- 1POWO — Amaranthus spinosus L. — Plants of the World Online (Kew), 2026
- 2GBIF Backbone Taxonomy — Amaranthus spinosus L. — GBIF, 2026
- 3Wikipedia EN — Amaranthus spinosus (spiny amaranth) — Wikipedia EN, 2026
- 4Wikipedia VI — Dền gai — Wikipedia VI, 2026
- 5Wikipedia ZH — 刺苋 — Wikipedia ZH, 2026
- 6Ảnh: Forest & Kim Starr (CC BY 3.0) — habit, flowers, spines and seeds — Wikimedia Commons — Wikimedia Commons, 2026
- 7Ảnh: Krzysztof Ziarnek (CC BY-SA 4.0); Thamizhpparithi Maari (CC BY-SA 4.0) — Wikimedia Commons — Wikimedia Commons, 2026