|Latin name: Amaranthus retroflexus
|Common name: Redroot pigweed
|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: 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
|Foliage: Leaves alternate, simple,
with distinct venation pinnately from midrib. Leaves have noticeably
|Flower: Flowers are green and
form terminal and axillary panicle like spikes.
|Cotyledon or seedling: Cotyledons
are long and narrow, with first true leaves appearing redish-purple in color.
|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.