In Touch: Shaw's agave

What do you do when you're gardening with a plant that is endangered?

“Hey, Paul, that Shaw’s agave that we took out a couple weeks ago is starting to bloom.”

That was Ralph, the intern who has been working with me over the last several months. It was the end of the day on Monday, when Ralph ran across the soon to be blooming agave. When I went over to take a look, sure enough, there it was laying on its side, with the characteristic asparagus stalk growing from its crown.

It’s no wonder to me that a lot of folks say that the Shaw’s agave is a member of the asparagus plant family. Photo by the author

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I had to remove the plant because it had grown over a small wall. The plant’s many barbs presented a hazard to folks walking by. The Shaw’s agave is a flowering plant, but it also reproduces by making clones of itself, pups alongside the parent plant. When I remove an agave, I leave the “family” of the agaves intact, only removing one or two of the clones.

The group of clones from which I removed the Shaw’s agave. The brown area on the mid lower right is the scar left over from the extraction. The wall can be seen in the lower right corner. Photo by the author.

The range of the Shaw’s agave and where you can find them now

Data for these maps is from Natural Earth and SanGIS. The maps were created using QGIS.

There are two subspecies of Shaw’s agave. One that grows in the Mexican desert, and this one, the coastal one (Agave shawii subsp.shawii). In the above map, the dot along the coast indicates the only place in San Diego County, or the U.S. for that matter, where the Shaw’s agave still naturally occurs. That bit of land that juts out into the ocean like the trunk of an elephant is called Point Loma. The side of Point Loma facing the ocean is a promontory, a cliff that plummets straight down to the Pacific Ocean. The agaves occupy a patch of land at the edge of this promontory. Many of the agaves cling precariously to the edge of that cliff.

The other dot, along the bay, indicates where I work* and where I have a plethora of agaves. The plant’s historic natural range would have been from about ten miles north of La Jolla on south, occupying the five to seven miles of land inland from the coast. Agaves have been extirpated from this area primarily because most of the natural landscape has been paved over for housing development, strip malls, and highways. There are places south, down along the Baja coast, where there are still natural stands of Shaw’s agave, but if you see it anywhere in the U.S., it’s been planted there by somebody.