12 Days of Conifers: Five Needles on a Foxtail

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For Day 3 of 12 Days Of Conifers, we're featuring the long-lived foxtail pine (Pinus balfouriana) and a close-up on its cones.

Pine cones at different stages of development on a foxtail pine, with one open cone and other cones tightly sealed

Foxtail pine cones in different stages of development.

(Credit: Nate Stephenson, USGS Western Ecological Research Center. Public domain.)

Foxtail pine is a California endemic species, with one subspecies found in the North Coast Range and Klamath Range, and another subspecies in the southern Sierra Nevada. Foxtail pine is a high-elevation, subalpine species, and like many other subalpine pines it is relatively short in stature, slow-growing, and long-lived. It doesn’t live as long as its close relatives the bristlecone pines, but foxtails can live at least 2100 years.

At first glance, it may look like this pine has very thick needles, but what you are actually seeing is bundles of five needles that attach to the branch at a single point. The number of needles in a bundle is an important distinguishing character for pine trees. Foxtail and many other high-elevation species, like whitebark pine, bristlecone, and Western white pine, have five in a cluster, while ponderosa pines typically have three, and lodgepole pines have just two.

Small yellow cones on the branch of a foxtail pine

Male cones of a foxtail pine.

(Credit: Janet Fryer, USFS.)

This photo also shows off cones in different stages of development. The small, tightly closed purplish cones are the most recently formed, the ones on the right older but not yet opened, and the one in the center of the image has already opened and dropped its seeds, which are tucked at the base of the scales. These are all female cones, but you might also spot male cones on a foxtail pine, which are small and yellow.

Foxtail pine is one of several species that USGS scientists has been monitoring for more than 20 years to better understand long-term population trends.

For example, a recent publication examined how white pine blister rust (an infectious tree disease) has affected four pine species found in Sequoia-Kings Canyon National Parks over the past two decades. Of the four species, foxtail pine was the only one where there were no observed infections in the study plots over the course of the study, even though foxtail has been susceptible to the disease elsewhere (some foxtail pines outside the study plots were infected). Why the Sequoia-Kings Canyon foxtail pines have been so rarely infected thus far is still a mystery, but local environmental factors are probably part of the story.

You can read the open-access study here.

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Foxtail pines on a rocky mountain slope

Foxtail pines on a mountain slope

(Credit: Janet Fryer, USFS.)