Needle burr (spiny amaranth, spiny pidweed, spring pigweed)
Stems: Needle burr is a robust, branched, upright plant that grows to 50-100cm, occasionally reaching 1.2m or more if growing amongst tall plants such as maize. The stem is stiff when mature and is ribbed lengthwise.
Leaves: The dull green leaves are shaped like a spearhead, and are borne on long slender stalks. The leaf blade is up to 4cm wide and 8cm long, and has large numbers of veins running off the midrib. The blade sometimes has a pale patch or v-shaped mark on its upper surface, although leaves of plants collected from Northampton had a large purple blotch on the upper surface. The characteristic pairs of spines arise on the stem where each leaf is attached.
Flowers: Flowering plants bear large numbers of small papery greenish-white flowers crowded together in a long tail-like spike, which extends beyond the leafy part of the stem. Shorter spikes and clusters of flowers are found lower down the stem. The chaffy bracts that surround each flower are tipped with a short spine.