Exploring Ultramafic Plant Communities – The Weirdness of Southwest Oregon

Checking out Kalmiopsis leachiana

Southwest Oregon is a geologic anomaly compared to the rest of the state.  This area comprising most or all of Josephine County is a section of Mesozoic continental crust from the east that because of plate tectonics has been pushed upon the rest of the state over eons. The chemistry of the rock in this serpentine dominated area is also quite different from the surrounding counties. Serpentine contains a good bit of magnesium and the levels become so high in the related developing soils that the soil is toxic to many plants.  However, those that had been in the periphery of the area have evolved to adapt these ultramafic soils, and over millions of years quite a bit of speciation has taken place and these plants that can tolerate the magnesium have taken over the area.  Not surprisingly, many of these plants are only competitive in these magnesium rich soils and are therefore limited to just the Josephine county area and a tad more that extends into California. In other words, these plants are rare.  Maybe not always rare in numbers, but certainly rare in geographic distribution.  Here we are on a trip this June 7-9th to see Kalmiopsis leachiana  a plant only found in the high elevation areas of these ultramafic lands.  It was just one of many uncommon plants that we saw on a trip that I helped lead for the Eugene Natural History Society.

Checking out one of our destinations – Black Butte,

A north facing serpentine hillside where Jeffrey (Pinus jeffreyi) and sugar pine (Pinus lambertina) mix in incense cedar (Calocedrus decurrens) and Douglas fir (Psuedotsuga menziesii).  South slope become heavily dominated by just Jeffrey pine

Cypripedium californicum – The California Ladyslipper orchid, A serpentine endemic.