Pigweeds: Edible but Invasive

pigweed (Amaranthus sp.)

Back in August, I received an email from Ronald Chong, who gardens in Hacienda Heights.

Chong sent a picture of a plant for which he sought identification.  I told him it looked like pigweed but we needed to see it flower before making a positive identification.  Sure enough, one month later, when it began to bloom, it confirmed its pigweed identity.
When it comes to plant identification, leaf characteristics are notoriously deceiving.  To take one example, consider a jacaranda leaf.  If you had no idea of its identity and had to guess, and were told only that it was an arboreal species you would almost certainly classify it as belonging to the legume or pea family (Fabaceae) on account of its pinnate or bipinnate feathery leaflets.  Such leaves are typically seen in leguminous trees such as Acacia, Cassia, mesquite, honey locust, flamboyant (Delonix regia), and tipu tree.  Yet jacaranda belongs to the bignonia family and is kin to the wide spectrum of trumpet vines, so-called on account of their trumpet shaped flowers, a shape seen in jacaranda blooms as well.
Getting back to pigweed (Amaranthus spp.), I mentioned to Chong that it was edible and his wife promptly decided to cook it so they could sample it for taste.  She “snipped off a bunch of leaves and added them to home made chicken broth.  The leaves tasted just like spinach.”  This was not a surprise since spinach belongs to the same family as pigweed, which most likely gets its name from the fact that it is also utilized as fodder for pigs.  Other edible members of this family include beets and Swiss chard, as well as lambsquarters or goosefoot (Chenopodium spp.), another edible weed.  Seeds of one goosefoot species are used for making quinoa, which was domesticated by people living in the Andes Mountains between three and four thousand years ago.
Pigweed itself was a staple of pre-Columbian peoples living in South, Central, and North America.  Not only is pigweed foliage edible, but “pigweed seeds are highly nutritious and may be collected after shaking the tops of older plants. These seeds may be eaten raw, cooked as hot cereal or mush, ground into flour, or popped like popcorn” (web.ku.edu).
Unfortunately, before we get carried away about turning weeds into food and eliminating world hunger with plants that barely need cultivation, there is a downside to pigweed, too, brought into focus by another communication — this one from Bloomberg Businessweek of January 11, 2018 — I subsequently received courtesy of Ronald Chong.  It has to do with a new technology that is slowly turning weed abatement or elimination into a high tech, AI (artificial intelligence) enterprise.  Some day, it seems, weed pulling will no longer be necessary.  But first some background.
There is a certain monstrous pigweed species that is a scourge of cotton, corn, and soybean farmers.  A single pigweed plant of this type can grow ten feet tall and produce a million seeds in one growing season so that the potential for weedy invasion of enormous stretches of farmland is real.  In an effort to deal with this and other weeds, Roundup (a broad spectrum herbicide that kills most plants) resistant cotton, corn, and soybeans were developed.  What this meant was that a farmer could spray a field with Roundup without having to discriminate between weed and crop seedlings since sprayed crop seedlings would not be affected by Roundup applied to them.
This was thought to be a miracle cure for weedy fields until, in 2006, a farmer in Arkansas noticed that not all pigweeds sprayed with Roundup were dying.  By 2008, there were 10 million acres of Round-resistant weeds in the US and today that figure has climbed to 70 million acres, approximately equal to the size of Nevada.
Enter artificial intelligence.  A company called See & Spray has perfected a robot that makes a distinction between weed and crop seedlings.  Tens of thousands of images of cotton seedlings, for example, were laboriously photographed.  These images were then uploaded into a robotic weeder that attaches to a tractor.  The weeder’s cameras scan every seedling along the way, ignoring anything that resembles one of the archived cotton seedlings and delivering a micro-jet of old-fashioned herbicide into each weed.
One of the advantages of this technology is that tilling the soil, still a popular method of weed control, is unnecessary.  Whether on the farm or in the garden, it is never advisable to till the soil since aerobic bacteria and other beneficial soil-dwelling micro-organisms are destroyed in the process.
Imagine placing a weeder robot on a lawn and seeing it zap every weed while leaving the grass alone.  As See & Spray has demonstrated, this technology is right around the corner.  Already, a large variety of self-mowing lawn mowers are available, ranging in price from $600-$3500.  In the same way that a robotic vacuum cleaner takes care of your floor without you moving a finger, you can now mow your lawn.
Tip of the Week:  Amaranthus (a = not, maranthus = dying) means eternal.  It refers to the everlasting quality of the flowers of most Amaranthus species which stand up for months in dry flower arrangements.  Celosia or cockscomb is one famous annual flower among the amaranths, with flowers in red, pink, yellow, and orange.  Its flowers are either plume-shaped or fasciated cockscombs. No plant is more tempting in the nursery and no plant fails more regularly and miserably in the garden than Celosia. The reason for its quick garden demise is overwatering. In the manner of all Amaranthus flowering species, it should not be soaked more than once a week and always with a soaker hose or drip irrigation. A most distinctive type of celosia, up to three feet tall, has maroon foliage and red flowers.  Globe amaranth sports violet-magenta spheres with a straw-like texture.
Most famous among the amaranth flowers is love-lies-bleeding (Amaranthus caudatus), growing up to 10 feet tall with long tassels of scarlet or burgundy red flowers. A most attractive aspect of this species is its ease of cultivation. Just broadcast seeds over bare ground in late winter or early spring and you will see them germinate within two weeks. They will grow quickly enough into flowering plants and bloom nonstop into the fall.
Do not pick all the flowers for your arrangements. Let some go to seed and you will be rewarded the following spring with a self-sown crop of new plants.
Amaranthus tricolor is an ornamental species grown strictly for its variegated foliage.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.