September 11, 2008

Tree Walk: Unidentified locusts - update

Les of A Tidewater Gardener identified the Le Conte locusts as Robinia pseudoacacia 'Purple Robe.' (Thank you Les.) The illusive "Illustrated Guide to the Street Tree Planting Program" published by the City of Berkeley lists the tree as Robinia ambigua 'Purple Robe.' The guide is available at the reference desk of the Berkeley Library's central branch; it is not available online.

2 comments:

  1. I am surprised that locusts are recommended for street trees. In Seattle, we had a bunch in our previous garden and they were pretty high maintenance. They grow like weeds, sprout seedlings everywhere, the limbs interfere with power lines, they drop small petals and leaves that are hard to clean up and clog storm drains, etc. There are those few days when their blossoms are perfuming the neighborhood, but that's a pretty brief hiatus from the other stuff. Maybe this variety, with its very pretty-colored blooms, causes less trouble??
    - Karen
    http://greenwalks.wordpress.com

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  2. Karen, thank you for the question.

    Robinia pseudoacacia is listed as invasive in the USDA Plants Database (http://plants.usda.gov) and on the California Invasive Plant Council website (http://www.cal-ipc.org).

    Robinia x ambigua 'Purple Robe' is a cross of R. pseudoacacia and R. viscosa and is drought tolerant, which is important in this area. According to Univ. of Conn. Horticulture (http://www.hort.uconn.edu), 'Purple Robes' "form fewer seeds," making the variety less invasive, perhaps.

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