UMass Extension Weed Herbarium

Amaranthus spinosus

Common Name: 
spiny amaranth, spiny pigweed
Scientific Name: 
Amaranthus spinosus
Family Name: 
Amaranthaceae - Amaranth Family
Identification Notes
Life Cycle: 
introduced annual, reproducing by seed
Stems: 
upright, branched, smooth, reddish, pair of sharp spines at nodes
Growth Habit of Spiny Amaranth
Growth Habit of Spiny Amaranth
Leaves: 
alternate, oval, entire, smooth, long petiole, often water-marked
Leaves of Spiny Amaranth
Leaves of Spiny Amaranth
Flowers: 
terminal spikes - green, small, mostly staminate (male); axillary clusters – green, small, mostly pistillate (female)
Female Flower Clusters of Spiny Amaranth
Male Flower Clusters of Spiny Amaranth