In 1952, a botanical survey was initiated to document all the known vascular plants that occur on the Center's 5,358 acres. By 1954, nearly 450 species were recorded. Since then an additional 213 species have been found, bringing the total number of vascular species and infraspecific taxa to 663. These are found in 354 genera in 95 families. Currently, 154 introduced species occur at the HREC (23.3% of the total vascular flora). One-third of the introduced species are annual grasses, followed by annual forbs primarily in the aster and pea families. In addition to the vascular plants, 51 moss and 3 liverwort species have been found at HREC; an inventory of lichens was conducted in the fall of 2000.
A plant list for the Center, arranged alphabetically by family, can be downloaded.
The Mediterranean Winegrape Cultivar Vineyard is a 2.0-acre vineyard, planted in the Niderost Pasture at 560' elevation. The vineyard consists of twenty Italian and Rhone varietals on Teleki 5C rootstock planted in six replications of ten vines for a total of 1200 vines. Vines are planted on a 7x10-foot spacing and are trained on a vertical shoot-positioned trellis system. The location is Willits soil of the Pleasanton Series alluvial soils (Gowans 1958). The vineyard is equipped with an overhead sprinkler system with automatic Orotemp frost protection, automated drip irrigation system, and non-potable water.