Amaranthus powellii (Powell amaranth)
Image credit: Andrew NeelIdentification tips
Tip #1: the name of the amaranth genus comes from the Greek amaranths, "unbeatable", referring to the long-lasting flowers. Just remember who this species is "sister", from Amaranthus palmeri so just remember the Chuck Norris (unbeatable), because these days the A. palmeri is the Chuck Norris of the weeds. While the name of the species powellii honors John Wesley Powell, the famous explorer of the Colorado River and the Grand Canyon.
Plant shape
2nd Identification Tip: an erect annual herb growing to a maximum height near two meters.
Leaves
3rd Identification Tip: It has leaves up to 9 centimeters long, those on the upper part of the plant lance-shaped and lower on the stem diamond or roughly oval in shape.
Stem
4º Identification tip: the stem just as the leaves tend to be red or green and covered by hair.
Flowers
5º Identification tip: the inflorescences are numerous and are present at the end of a branch and in the armpits of the leaves, the groups of flowers in the armpits of the flowers are large, about one third of the size of the main inflorescence.
Seeds
6º Identification tip:it is not possible to identify the seeds among the genus amaranthus,so it is worth checking, small, black and shiny seeds. If you have guts you can try to identify the seeds here
Seedlings - the terror of all
He's not afraid of anything
7º Identification tip: the cotyledonary leaves are long and thin, the first true leaves have dark red or dark green coloration, this coloring becomes clear as the plant develops..
Extra references:
https://cpb-us-w2.wpmucdn.com/u.osu.edu/dist/7/3461/files/2016/01/PM1786-ytzm2t.pdf
http://swbiodiversity.org/seinet/taxa/index.php?taxon=105&clid=2537