Latin name: Amaranthus retroflexus L.


Family:  Amaranthaceae


Common name: Redroot pigweed

plant thumb Life cycle: warm season annual, reproduces solely by seed .  This weed will germinate all year long, but first frost will annihilate all redroot pigweed.  So control measures are not necessary to kill this weed late in the year.

habit thumb Habit:  Tall and erect habit, usually 2 to 4 feet tall.  Although can grow and appear prostrate if mowed repeatedly.  This weed can flower when only several inches tall.

leaf thumb Foliage:  Leaves alternate, simple, with distinct venation pinnately from midrib.  Leaves have noticeably long petioles.

flower Flower:  Flowers are green and form terminal and axillary panicle like spikes.

cotyledon Cotyledon or seedling:  Cotyledons are long and narrow, with first true leaves appearing redish-purple in color.

red root thumb Roots:  Redroot pigweed develops a deep, thick taproot.  Near the soil surface, the taproot is often pink in color (hence the name).


Notes:  In my opinion, this is the most widely distributed weed in Oregon field nurseries.  Though many growers say it easy to control, it is one that I've observed as most frequently uncontrolled.


This weed does not occur in container nurseries.




Return to the Weed Species Page

Return to the Weed Management Homepage



Email comments to James Altland