As much as I love agaves, the beaked yucca (Yucca rostrata) is my favorite succulent for the landscape. Native to western Texas and northern Mexico, it grows on rocky slopes and ridges and tolerates harsh climatic extremes both in the summer and in the winter. It is reputed to take temperatures below 0°F, making it one of the hardiest of all yuccas.
Over time—decades, really, since it’s a very slow grower—it forms a trunk to 12 ft. tall. Last year I saw specimens maybe 9 ft. tall at The Living Desert in Palm Desert, CA, and they were impressive with their circular heads of stiff gray-green leaves. These plants were left in their natural state, i.e. the old leaves were left on to form a skirt much like you would see on a palm tree. In a garden setting, the dried leaves are often trimmed, creating a more manicured effect:
Over the last few years, I’ve accumulated five Yucca rostrata, ranging from plants in 1-pint containers to the 2-ft. specimen I bought at Poot’s Cactus Nursery in Ripon, CA last November. Four or five years ago, Yucca rostrata was all but impossible to find locally. Now I see it occasionally in independent nurseries. While small plants (typically round 1-pint containers) cost the same as other perennials, about $6, the price of older specimens that have begun to form a trunk quickly climbs into the hundreds of dollars.
 |
| My collection of Yucca rostrata |
Yucca rostrata seems to be a fairly variable species, especially in terms of leaf color. The standard color is grayish green:
A tissue-cultured selection called ‘Sapphire Blue’ is supposed to be particularly blue, but mine (seen two photos above in the terracotta pot on the left) is the same grayish green as the regular form. However, my specimen from Poot’s has a very strong powdery blue cast:
 |
| Close up of the same plant |
Above I said I have five Yucca rostrata. However, if you look at the photos closely, you’ll see six plants. The sixth, seen on the right in the next photo, is Yucca linearifolia. Discovered in northern Mexico in the 1980s, it was initially thought to be a subspecies of Yucca rostrata. Since then, some taxonomists have promoted it to species status. Since seed had been virtually impossible to obtain, it was put into tissue culture and is slowly becoming more available.
The leaves of Yucca linearifolia are narrower, less stiff, and greener in color than Yucca rostrata. I can definitely see the difference in my own plants, but in older specimen that difference seems to less pronounced: Looking at these photos, I would have thought that these are Yucca rostrata instead of Yucca linearifolia. In practical terms, these differences are irrelevant because both species are supremely architectural and equally gardenworthy.
 |
| Yucca rostrata (left) and Yucca linearifolia (right) |
Below are some additional photos of Yucca rostrata from various places in Northern California. Since it’s so cold hardy, it has the potential to grace gardens in much of the U.S. and Europe.