alkali buttercup American vetch Canada thistle Carolina whitlow-grass common cattail common hops rough purple gerardia fragrant aster giant ragweed ground spurge hoary cress leafy spurge marijuana musk thistle nettle-leaved verbena pale umbrella wort prairie larkspur prostrate vervain purple loosestrife rough-leaved dogwood slender dalea virgin’s bower Virginia stickseed wahoo western rock jasmine white smartweed wild strawberry