INVASIVES: The canes of the deciduous Japanese knotweed can punch through concrete.   Eric Wrubel, NPS
Invasive plants are not uncommon in Marin, but a relatively new encroacher in the San Geronimo Valley has a particularly fearsome international reputation. Fallopia japonica, or Japanese knotweed, is considered one of the world’s 100 worst invasive species. The plant can survive on volcanic slope

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