Vitus vinifera

Not normally considered an aggressively invasive plant, various strains of non-native Vitus vinifera have taken over nearly all of this northern California valley, with help from another highly invasive species, Homo sapiens.



While the native Quercus agrifolia, Toyon (Heteromeles arbutifolia), Coast Redwood (Sequoia sempervirens), and Madrone (Arbutus menziesii) are still found on the steeply sloping walls of the valley, and though a few of the magnificent Quercus lobata manage to survive on the valley floor, most all areas are taken up by Vitus.

Madrone (Arbutus menziesii):


Oak against a misty curtain wall of Sequoia:
 





Not that I'm complaining, you understand.  While human history is written by the winners, it can be noted that invasive species are identified from the point of view of the losers.