The Sonoran Four: Agave, Yucca, Sotol, Beargrass
If you look out the window as you drive past Tucson, Arizona, you'll probably notice spiky plants bursting from the ground.
"Duh, they're cacti," you may be thinking.
But wait! Aside from the cacti, there are dozens of rosette-forming species that put up tall flower stalks called inflorescences. Most of these knife-sharp pompoms belong to one of four genera that I call the Sonoran Four:
1. Agave (genus Agave)
2. Yucca (genus Yucca)
3. Sotol (genus Dasylirion)
4. Beargrass (genus Nolina)
Let's take a closer look. See if you can tell the difference!
Agave, a genus native only to the New World, is easily confused with Aloe, a genus native only to the Old World (mostly Africa). The two genera belong to different families and appear similar due to convergent evolution.
|Agave from the top down.|
Agave have thick, succulent leaves with serrated edges. Each leaf ends in a sharp, pointed tip.
|Jane points out a dead agave inflorescence.|
These plants flower only once in a lifetime before dying. They spread predominantly by underground roots that put up new shoots. The flower stalk looks like multilayered tree, and the flowers are usually yellow.
|Galen uses a desiccated agave as a weapon.|
|This notorious species, Agave schottii, is known as "shindagger" because it draws blood on contact.|
Yucca leaves are thinner and straighter, without the succulent base of agave leaves. Instead of serrated points, they are often edged with wispy, white hairs.
|This yucca species grows a trunk and beard with time.|
Unlike agave, most yucca can bloom more than once before they die. Their flowers are white and bell-shaped. Some famous yucca species grow trunks, like the Joshua tree (Yucca brevifolia) and the soaptree yucca (Yucca elata).
|The roots of soaptree yucca, Yucca elata, are used to make soap.|
Sotol, also known as "desert spoon" because of the concave bases of its leaves, goes by the Latin name Dasylirion wheeleri. Its leaves are edged with tiny, upward-pointing serrations. Its inflorescence consists of thousands of small, white flowers in a dense, vertical plume.
|Jane shows off the height of an impressive sotol inflorescence.|
Beargrass includes several species in the genus Nolina. It is not a grass, but a member of the Asparagus family.
|It looks like a clump of soft grass at a distance, but beargrass will leave you with worse than a grass-cut.|
The leaves are narrower and floppier than those of Agave, Yucca, or Sotol, but they are just as deadly to bare skin. These leaves are edged with nearly-microscopic serrations.
|The narrow, microscopically-serrated leaves of beargrass.|
|The beargrass inflorescence consists of spindly, upward-growing branches coated in creamy, white flowers.|
I tended to find Yucca and Agave at lower elevations, while Sotol and Beargrass became more common as I climbed higher. Keep paying attention, and your Sonoran Four identification skills will get better and better. You know you've made it when you can lean out the car window and identify rosettes at 40 miles per hour. But don't forget to get up close and personal with these spiny friends, too. The details hold many surprises.