Echinoagave, Paleoagave, Paraagave, oh my

As Bob Dylan once said, “There is nothing so stable as change.” That’s true for a lot of things, but especially for taxonomy. Many people hate it when the botanical names they’ve painstakingly learned become something else. Others embrace it as a corollary of progress. Me, I’m OK with it as long as there’s a good reason.

A big brouhaha ensued when in 2014 five new genera were split off the genus Aloe: Aloiampelos, Aloidendron, Aristaloe, Gonialoe, and Kumara. This wasn’t some random flight of fancy, but the result of molecular studies that shed new light on the evolutionary origin of what we call aloes.

Now something similar is happening to agaves, although on a smaller scale. A couple of months ago (January 2024), a team of Mexican botanists published an article titled “New Genera and New Combinations in Agavaceae” in which they propose three new genera based on genetics, morphology, and the estimated time they diverged from the common ancestor of all agaves.

I know, this is stuff that makes your eyes glaze over, but it helps us better understand how agaves evolved and how closely related they are to each other. Humans want to bring order to the chaos of nature, and this is another small step in that direction. I won’t go into greater technical detail here, but if you’re interested, you can download the article from here. Unlike many other scientific articles, this one is free, i.e. not behind a paywall.

The vast majority of agaves will still be in the genus Agave – at least for now. Below are the three new genera and the species they contain:

Echinoagave

“Echino-” comes from the Greek word echînos (hedgehog) and means “spiny.” This new genus diverged from the genus Agave approximately 4.15 million years ago. It includes compact hedgehog-like species that are polycarpic, i.e. don’t die after flowering.

As proposed by the authors, the genus Echinoagave consists of these species:

1. Echinoagave albopilosa
2. Echinoagave cryptica
3. Echinoagave cremnophila
4. Echinoagave dasylirioides
5. Echinoagave gracielae
6. Echinoagave kavandivi
7. Echinoagave lexii
8. Echinoagave petrophila
9. Echinoagave rzedowskiana
10. Echinoagave striata
11. Echinoagave stricta
12. Echinoagave tenuifolia

Of these 12 species, only three are reasonably common in cultivation: Echinoagave albopilosa and the two closely related Echinoagave striata and Echinoagave stricta.

Echinoagave albopilosa

Echinoagave striata

Echinoagave stricta

Paleoagave

“Paleo-” comes from the Greek word palaios (ancient) and means, well, “ancient.” This new genus is the earliest to diverge from the genus Agave, approximately 6.18 million years ago. It includes species with unarmed, soft, curling leaves.

As proposed by the authors, Paleoagave has only one species:

1. Paleoagave bracteosa

Commonly known as the squid agave, Paleoagave bracteosa is a popular landscaping plant because (a) it’s almost completely unarmed and (b) it’s cold-hardy to 10°F. According to Loree ‘danger garden’ Bohl, it made it through Portland’s record-breaking winter unscathed.

Paleoagave bracteosa

Paleoagave bracteosa flowers

Paraagave

“Para-” comes from the Greek word pará (akin to) and means “closely related.” This new genus diverged from the genus Agave approximately 4.25 million years ago. The species in this genus have larger rosettes with a small number of large non-curling leaves whose margins are either toothless or sport only a few sparse teeth.

As proposed by the authors, Paraagave has only one species:

1. Paraagave ellemeetiana

Paraagave ellemeetiana resembles Agave attenuata, but has fewer leaves. Both species are tender, which is why they’re not typically used as landscape plants in Northern California where I live. On the other hand, in Southern California, Agave attenuata is the most popular agave for landscaping, and Paraagave ellemeetiana is occasionally seen as well.

Paraagave ellemeetiana

There you have it, a few new names to learn, especially if you want to impress (or annoy) fellow plant nerds. In horticulture, nothing will change in the short term. In fact, I’m sure that even in five years, nurseries will still use the old names.

😉 In a recent blog post, Tony Avent, the founder of Plant Delights Nursery, wondered out loud what to call hybrids involving these newly named agaves (like Paleoagave bracteosa × Agave lophantha) and made several tongue-in-cheek suggestions like ×Closetoagave, ×Sortofanagave, and ×Notquiteanagave.

© Gerhard Bock, 2024. All rights reserved. To receive all new posts by email, please subscribe here.