North America’s second-rarest pine

Jeffrey (L) and Washoe (R) pines at Galena Creek Park

During last year’s trip to Lake Tahoe, I made it a goal to find all of the 11 conifer species occurring naturally in the Lake Tahoe Basin. It took some effort, some good references (Arno 1973, Graf 1999, Lanner 1999, and Peterson 1975), and the help of an especially knowledgeable associate at the U.S.D.A. Forest Service headquarters in South Lake Tahoe, but I succeeded in my quest and later wrote two posts covering the Lake Tahoe conifers (Trees of Lake Tahoe – The Pines, Trees of Lake Tahoe – The “Other” Conifers). In the first of the posts covering the six species of pines, I added the following footnote:

Two additional species of pine – Washoe pine (Pinus washoensis) and single-leaf pinyon pine (P. monophylla) – are often treated as occurring in the Lake Tahoe area. However, they are of sporadic occurrence on the eastern slopes of Mount Rose, and thus do not occur within the Tahoe Basin proper.

Of these, I am quite familiar with single-leaf pinyon pine. Widespread on isolated mountain ranges throughout the Great Basin into eastern and southern California and Baja California Norte, I have encountered it during many of my field trips out west and reared a number of buprestid species from its tough, scrubby branches (including 2 specimens of the rarely encountered Phaenops piniedulis). The other species, Washoe pine, was a new one on me, and it is, in fact, the second-rarest species of pine in all of North America (Torrey pine, Pinus torreyana, being the rarest). Well, that was all it took to make me commit to finding this species on this year’s return to Lake Tahoe.

Washoe pine cones surround a larger Jeffrey pine cone.

Washoe pine grows only in a few locations, primarily in northern California with the best stands found in the Warner Mountains in Modoc County. In the Tahoe area, Washoe pine grows only on the eastern slope of Mt. Rose in Nevada, where it is limited to the upper reaches of Galena Creek (Graf 1999, Lanner 1999). It is apparently very similar to Jeffrey pine (P. jeffreyi) – the most common pine in the Tahoe area – but seems to be more closely related to ponderosa pine (P. ponderosa), which occurs at lower elevations and barely makes it up to the Tahoe area (some authorities even question the distinctiveness of this species, instead considering it a high elevation variety of ponderosa pine). All three species are 3-needled and grow into tall, pyramidal trees with widely spaced horizontal branches. Like ponderosa pine, the bark of mature trees forms broad yellowish plates separated by black fissures (the bark of Jeffrey pine is often more reddish with plate more narrowly separated). The resin of Washoe pine is also chemically similar to that of ponderosa pine, both of which differ from the heptane-producing resin of Jeffrey pine. However, Washoe pine cones more closely resemble those of Jeffrey pine, being somewhat smaller but sharing the “inward-curved” prickles on the scale tips that make them easy to handle (those of ponderosa pine point outwards, making them very prickly to handle).

Ponderosa (L) and Washoe (R) pine cones. Note smaller size and outward-pointing spines of ponderosa pine cone.

Jeffrey (L) and Washoe (R) pine cones. Both have inward-pointing spines, but Washoe pine cone is smaller and more loosely built.

None of my references had any specific locality information for Washoe pine beyond what I’ve stated above, but a little bit of Google snooping through conservation action plan documents revealed that the species occurred at Galena Creek Park, so early in the morning daughter Madison and I made the one-hour drive from South Lake Tahoe to the park. Arriving at the park, I was disappointed to find nobody manning the headquarters, no maps in the park information board – indeed, no information whatsoever about the occurrence of Washoe pine within the park and where it might be found. The only clue that there was something special about the pines at this place were the wooden signs around the parking and picnic areas stating “Collection of pine cones prohibited.” I reasoned that it would be very difficult to distinguish the species by its needles, bark, or form, but that the pine cones should be easier to distinguish. I also had no idea whether the pines would occur close to the parking area or if we would need to hike into the area to find them. So, we just began picking up pine cones. For a time, all of the pine cones seemed to be typical Jeffrey pine (abundant in the area) with an occasional ponderosa pine (just making up the 6,200′ of elevation in this area). Ever concerned that I might be missing a subtle difference, I studied each “Jeffrey” pine cone carefully looking for any reason to regard it as truely smaller than normal. Within about 15 minutes, however, we found it! Picking up the pine cone, it had the compact build and inward-pointing spines of a Jeffrey pine, but it was smaller and a little more loosely built. I looked at the trees above and could see no difference from what I would expect for a Jeffrey pine. Further looking revealed numerous cones of the same type – each tree we found them under was otherwise indistinguishable from Jeffrey pine (at least to this eastern U.S.-based wannabe botanist). Nevertheless, it was clear that we had found Washoe pine, and that it was quite abundant within this small watershed that we were exploring. Jeffrey pine was also common in the watershed, and an occasional ponderosa pine could be found. I took photos of mature individuals of each of the three species, identified conclusively by way of the cones found underneath them, to show how similar in appearance the three species are.

Pinus ponderosa

Pinus jeffreyi

Pinus washoensis

Madison and I later hiked out of the watershed into the higher elevations of Mt. Rose (from where these ants were photographed) – we noticed that almost immediately upon hiking out of the watershed the Washoe and ponderosa pines disappeared, and only Jeffrey pines were seen. Although I have seen it many times before, I was still hoping to see single-leaf pinyon pine, but none were seen.

REFERENCES:

Arno, S. F. 1973. Discovering Sierra Trees. Yosemite Association, Yosemite National Park, California, 89 pp.

Graf, M. 1999. Plants of the Tahoe Basin. Flowering Plants, Trees, and Ferns. A Photographic Guide. California Native Plant Society Press, Berkeley, 308 pp.

Lanner, R. M. 1999. Conifers of California. Cachuma Press, Los Olivos, California, 274 pp.

Peterson, P. V., and P. V. Peterson, Jr. 1975. Native Trees of the Sierra Nevada. University of California Press, Berkeley, 147 pp.