For a rare plant enthusiast, the Ridgecrest Field Office in the Western Mojave desert is a dream come true. In our district, we have 33 different rare and endemic species, which constitutes about 5% of our flora. There are two kinds of rare plants we in the district; ones that are found in only one location, and those with a wider distribution. For the former, there are cases where we can go and count the exact number of individuals in the known population.

Astragalus ertterae

Such is the case with Astragalus ertterae,for which the whole known population is found on a single hillside, and is composed of roughly 14 plants. The other end of the spectrum falls onto Cymopteris deserticola, which has a large distribution over many miles, but is limited to very specific habitats within that distribution. One of our most extreme cases of this is Astragalus geyeri var. geyeri, which is on our list, despite being found across 9 of the western states. Again, what makes it rare is that it is found only in small, isolated pocket populations, which are disjunct from each other by a significant distance and physical impediments, much like being on small islands in the ocean. Yes, they are widely distributed, and yes, they are the same species, but they are still very limited in their distribution.

When monitoring these plants, we make extensive use of GPS/GIS technology. Our standard sampling method is to travel to the site in question, usually one with a historic record of the species. When we begin the inventory or monitoring, we set up the tracker on the unit, which will trace our path as we search.

Cymopteris deserticola

When we locate a rare plant, we mark one waypoint for each plant found. After returning from the field, the data is projected onto a GIS system, with ARCmap being the default. The purpose of this method is to not only provide a detailed inventory of the species, but allows us to monitor not only where the plants are found, but where they are not found, which can be just as valuable for interpreting where the species is tied to. By using satellite photos of sites, we can project the known occurrences, and extrapolate where other populations might be found.

Among our rare plants, there a some where the differences between the rare and common species are easily discernible, while in others they are not so easy. One of my jobs has been to help assess the status of a plant, and whether or not it is one of the rare ones. It can be a difficult job, but it is ultimately very rewarding.