spiny amaranth
Family
AmaranthaceaeScientific Name
Amaranthus spinosus
Other Common Names:
prickly amaranth
thorny amaranth
Habit
This summer annual can be found flowering from May through October.
Leaves
The alternately arranged leaves occur on long petioles and are ovate in shape. The leaves grow from 1 1/4 to 2 1/2 inches in length. The erect branching stems can exceed 5 feet in height.
Identifying Characteristics
At the base of each leaf petiole are two 5 to 10 mm long spines, giving the Spiny Pigweed its name.
Flower Seed Head
The seedheads occur in clusters at the ends of stems arising from the leaf axils.
Seed Fruit
The seeds develop in a utricle 1 1/2 to 2 mm in length.
Where Found
This plant prefers disturbed sandy loam soils, but can grow in a variety of conditions.
Growth Habit
upright and nonwoody
Thorns or Spines
present
Approximate Flower Diameter
pencil
Dominant Flower Color
green
Flower Symmetry
Varies:
radial symmetery,
bilateral symmetry
Leaf Hairs
no hairs
Leaf Shape
oval
Leaf Arrangement
alternate
Leaf Margin
entire
Leaf Structure
simple
Leaf Stalk
shorter than leaf
Stem Hairs
no hairs
Stem Cross Section
round or oval
Milky Sap
not present
Root Structure
taproot
Life Cycle
summer annual
Ochrea
not present
Plant Type
Herb