Friday, June 18, 2021

Two Great Basin shrubs—each showy in its own way

Mountain mahogany in flower, field assistant for scale; Kingston Canyon, Nevada.
Like the Great Basin itself, many of its shrubs strike people as drab. Sagebrush, bitterbrush, snakeweed, rabbitbrush, shadscale, and more—all have subdued green to gray foliage, and small unpretentious flowers. But like so many things, it all depends on our perspective.

For example, the yellowish flowers of curl-leaf mountain mahogany are less than a centimeter long and have no petals. But this simplicity is made up for by their abundance. At peak bloom, they turn the entire canopy yellowish brown.

Cercocarpus ledifolius var. intermontanus can be a shrub or small tree.
Flowers by the hundreds!
Mountain mahogany flowers. The sepals form a floral cup (hypanthium), with 10 stamens and a single pistil.
After fertilization, an impressive transformation of the pistil takes place, underscored in the name of the genus, Cercocarpus (Greek kerkos, tail, and karpos, fruit). The single-seeded ovary dries and hardens, while the style elongates to be come a tortuous and hairy "tail". Mature fruits persist for some time, creating beautifully frosted shrubs!

Mountain mahogany in fruit; courtesy Andrey Zharkikh via Flickr.
The leaves of curl-leaf mountain mahogany reminded Thomas Nuttall of those of Labrador tea, so he named it Cercocarpus ledifolius (ledum-leaved) in 1840. In the latest taxonomic treatment, three varieties  are recognized. The shrubs I saw in Kingston Canyon, Nevada, are var. intermontanus, which has leaves with revolute margins, but not strongly so; they aren't particularly hairy, and often glabrous above.

Nearby was a shrub with a very different kind of showiness, more in line with what people consider beautiful. It was covered in flowers that were large and colorful, at least by Great Basin standards. The petals were each about a centimeter long, and deep pink in bud becoming paler in flower. This is the desert peach, Prunus andersonii.

Desert peach branchlets become stiff and spiny with age.
Like the mountain mahogany, when the desert peach blooms, it does so in profusion. Can you imagine stumbling upon it in a stand of sagebrush?!

Prunus andersonii with sagebrush; courtesy Matt Lavin via Flickr.
We're familiar with many of Prunus andersonii's close relatives. Domestic peaches, cherries, plums, apricots, and more are members of the genus Prunus. But while the desert peach looks like a peach, complete with fuzz, there's no edible fleshy pulp around the seed.

Courtesy Jason Hollinger via Flickr.

Some will be surprised to learn that curl-leaf mountain mahogany and desert peach are in the same family. With such different flowers and fruit, how can this be?! But those of us who know the Rosaceae simply shrug in resignation. The rose family is notoriously diverse. It used to be divided into six subfamilies, most of which were treated as full-on families at one time or another. Now experts recognize three subfamilies, and within these, 16 tribes. Get the full details of this tangled web here.

Or perhaps you would prefer Robert Frost's thoughts on the Rosaceae:

The rose is a rose,

And was always a rose.

But the theory now goes

That the apple’s a rose,

And the pear is, and so’s

The plum, I suppose.

The dear only knows

What will next prove a rose.

You, of course, are a rose –

But were always a rose.

—Robert Frost, The Rose Family


Cercocarpus ledifolius in Flora North America

Prunus andersonii in Flora North America

Rosaceae in Flora North America

Mozingo, HN. 1987. Shrubs of the Great Basin. U Nevada Press.

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