Amaranthaceae

Family Amaranthaceae has a lot of members—over 2,000 species. You will likely recognize many of them. Some are ornamental—think of the garden annuals Gomphrena, Ptilotus, and Love-lies-bleeding (Amaranthus caudatus). The Celosias are also amaranths—you might know some of them as the old-fashioned flower Cock’s Comb.

redroot pigweed univ of delaware-001
Photo: Univ. of Delaware

Some Amaranth family members are delicious—such as spinach, quinoa, beets and chard. And some are extremely annoying, like the ubiquitous weed redroot pigweed (right).

What do all these plants have in common? How will we recognize other plants in this family? There are two approaches we can take.

The first option is to get all botanical. One website described the family’s characteristics as:

Leaves exstipulate and simple; opposite or alternate, hairy; flowers small, inconspicuous and usually with bracts and bracteoles, actinomorphic, arranged in spikes or racemes; perianth 2 to 5, uniseriate, green or coloured, free or united; stamens 3 to 5 free, dithecous, antiphyllous (opposite the perianth segments); gynoecium bi or tri-carpellary, unilocular with a single basal ovule; fruit one seeded nutlet.

Got that? Me neither. We could look up all the science-y terms and try to make sense of this, or we could try approach number two: stare at a lot of plants in this family and notice any similarities. While not foolproof, I find this to be a lot more practical. It’s simply getting a feel for the family. Once you have that mental image in mind, you can see if a new, unidentified plant fits in.

Take a good look at these photos plus the ones above:

You may notice that the flowers are a bit odd—they don’t seem to have normal petals surrounding the pistil and/or stamen. Rather they’re made up of bracts! That’s that gives the flowers a feathery appearance. A bract is a modified leaf at the base of a flower. While the actual flowers may be small and hardly noticeable, their bracts are often showy. In this case, the bracts are more colorful than the actual flower petals.

Now notice how they’re arranged. Every “flower” doesn’t have its own stalk. Rather, they are gathered into what botanists call racemes. Google dictionary defines a raceme as “a flower cluster with the separate flowers attached by short equal stalks at equal distances along a central stem. The flowers at the base of the central stem develop first.”

Those are two easy traits to watch for—feathery bracts and racemes.

Now let’s put your new knowledge into practice. It’s time for a little quiz: which of the following photos are members of the Amaranthaceae? (Scroll slowly, because the answers are at the bottom of the page.)

Answers:
Top row: Yes, this is a form of Celosia; no, this is Lantana.
Middle row: Yes, this is spinach; no, this is Ratibida; no, this is a trumpet vine.
Bottom row: No, this is a fruit tree in the genus Prunus; yes, this is Gomphrena.

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