The winter/spring 2011-2012 was pretty awful for much of the west. It was especially bad around Reno. I did not get out much to ski in the local backcountry. Oh well. The previous winter was a huge year with boatloads of snow well into late spring. The recent lack of moisture translated into an underwhelming year for flowers around Reno and across most of the Great Basin. One notable exception was antelope bitterbrush (Purshia tridentata). It is a pretty common shrub from the Rose family (Rosaceae) found growing with Wyoming sagebrush (Artemisia tridentata var Wyomingensis) in mid elevations up to mountain sagebrush (Artemisia tridentata var vaseyana) at higher elevation. It is a very important nutrition source for lots of wildlife, nesting habitat for songbirds and bitterbrush provides thermal and predation cover for large and small animals.
I was surprised in late April/early May when bitterbrush began flowering like there was no tomorrow. On Peavine Mntn it was difficult to find a single plant that was not flowering. And each plant was covered top-to-bottom with flowers. Turns out this was the case across much of Nevada.
The next photo was taken at the radio towers at Hoge Road for any who know the area. The shot shows numerous bitterbrush individuals each of whom is flowering (all the cream-yellow is the bitterbrush flowers). Also in the photo are Mormon tea, crested wheatgrass, willows, Wyoming sagebrush and probably other species I failed to mention.
So I wondered why bitterbrush was doing pretty much the opposite of every other plant. There were some things flowering this spring but not very much. Certainly none of the annuals that make Peavine lovely in the spring. I asked other biologist types if they were seeing the same thing and the sum total of the answers was yes. I’ve read a bit about the genus Purshia in Charlie Clements and Jim Young’s book ‘Purshia‘. Pretty interesting read for those who are interested in the ecology of the intermountain west and should be a must read for all natural resource students.
According to the people I talked to and the science I could read, Purshia species will make use of a high resource year (2011) with bud formation and lots of leader or stem growth then have a big flowering event the following year (2012). A friend from grad school looked at the formation of flower structures in the rose family that happened many years before the bud actually flowered. The species he looked at is alpine avens (Geum rossii) and I believe that in some cases, flower buds were formed that did not open for as many as five years.
There are a few species of bitterbrush around and I see quite often. The more common where I work is Purshia tridentata and the other less common is Purshia stansburyana also called cliffrose. The easy way to tell them apart is P. tridentata has seeds with no style branches attached.
The photo below is Purshia stansburyana or cliffrose and it has persistent styles attached to seeds. Accoutrements really is a better word.