• Trees that should never be planted in Pacific Grove

    By Bruce Cowan

    BLUE GUM EUCALYPTUS (Eucalyptus globulus)

    There are roughly 600 species of eucalyptus, all from Australia.  While some, such as red flowering gum, make satisfactory landscape trees, the one most common locally is definitely a problem tree.

    Problems include:

    Huge size and rapid growth–witness the two by the Pacific Grove Post Office, much too large for most yards.

    Branches can break and fall at any time.  Trees can blow over in strong winds, endangering life and  property.

    Bark and leaves litter the landscape and poison soil for other vegetation.  Round seed pods scattered around can cause sprained ankles.

    Extremely invasive–in the forest it crowds out native plants, including pines and oaks.  Under dense groves of blue gum, little will grow but numerous eucalyptus seedlings and poison oak.

    Extremely flammable; Eucalyptus forest fires in Australia are the hottest in the world.

    Cut down for removal, or after a fire, blue gum resprouts and grows quickly with many new trunks.

    Note: While honored as a home for overwintering monarch butterflies, the monarchs actually seem to prefer clustering on pines and cypress at P.G.’s Monarch Sanctuary.  Strong winds can blow butterflies more easily out of eucalyptus than out of pines or cypress, increasing monarch mortality.


    Acacias seen locally are all from Australia.  All have proven to be invasive in our forest, spreading by seed that can last  for decades in the soil.  All have flowers full of allergenic pollen; the pollen is what provides the yellow color.  Most are considered shrubs, not trees.

    BLACK ACACIA (Acacia melanoxylon) is a truly fast growing tree which can be deceptively attractive in early spring with its handsome form and cream colored, pollen-laden flowers.

    Invasive in the forest and in landscapes, it spreads not only by seeds but by suckers that arise from the roots, like bamboo.  One tree can eventually become a dense grove.  No respecter of property lines, black acacia suckers will come up and grow quickly in neighbor’s yards, in shrubs, against home foundations where they will eventually cause considerable damage if not pulled out.  Pulling is a temporary solution, as new suckers rise quickly.  An unwanted black acacia that is cut down for removal soon sprouts even more suckers that quickly become a forest of fast growing acacia trees.

    Blue gum eucalyptus and black acacias are problem trees, not only for the property owner but to neighbors as well, and are a threat to the natural forest.

    posted to Cedar Street Times on May 28, 2009

    Topics: Current Edition, Features, Green


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