Plants ho!

Fourche La Fave River, Ouachita NF near Y City, AR

I identified the first wild populations of R. viscosum on the banks of the Fourche La Fave River in west-central Arkansas.  After scouting probable habitat further north in the Ozarks without any luck, we made the decision to look further southwest.  Sure enough, some leads got us to the right place.

An R. viscosum population, naturally subdivided into 3 distinct subpopulations.  Red dots indicate occurrence of plants near flowering.

Parts of each subpopulation were situated in the floodplain of the river and, judging by the littered debris, appear that they are submerged when the river floods.  Others occurred on rocky bluffs adjacent to the river's edge. Below is a video showing the general habitat of subpopulation C, entirely situated in the floodplain.

None of the subpopulations occurred far from water.  A few individuals grew on embankments at the base of a hill, but after surveying the higher ground I concluded that this population occurred solely on the Fourche La Fave.  The soils in the floodplain varied differently in appearance than those on the high ground, and so I subdivided subpopulation B into a grid formation up the slope to sample the soils where R. viscosum was most abundant, somewhat present, and absent. This type of survey will be repeated in other populations to see if any soil properties are associated with increased or decreased occurrence.  

Subpopulation B schematic.  Plants were most abundant in the northeast end of this grid.

Photos of R. viscosum flower and spreading habit.  Scaled to my machete

     

The red individuals were the ones actually sampled for genetic analysis.  These individuals had flower buds that were either open or near opening, and will be used as "parents" to help us understand how certain traits behave.  I'll elaborate soon, but for now it is nice to have one population surveyed.  On to Oklahoma!