28 Oct

Baccharis halimifolia and local relatives

(Baccharis comes somehow from Bacchus, the god of wine.  Halimifolia refers to a different plant with similar leaves.)



Working in the Kiplinger Natural Area  in Stuart, Florida, today, John and George enjoyed a dozen wildflowers in peak display, so beautiful:   White-Snakeroot,  Bluecurls, Liatris, Coin-Vine, and so many more.     In the garden of native delights is a fall-flowering species with curious attributes,   Saltbush, Baccharis halimifolia.    In our area we have also Baccharis glomeruliflora (flowers in tight clusters) and B. angustifolia (narrow untoothed leaves), representing a widespread genus of over 350 species.


Hammock Snakeroot by John Bradford

For starters,  the distribution of Baccharis halimifolia is odd, with a population in eastern Canada, then a gap of over 400 km to New England, down the U.S., into the Caribbean and Mexico.    This is one widespread plant.   And then some:  it has escaped cultivation or otherwise invaded around the globe, even in the Mediterranean and in Australia, where it is a pest battled with a destructive rust fungus.   The species is not welcome in many places because it accumulates in pastures and is fatally cardiotoxic to some grazers.  I don’t know where the poisons reside, but the leaves have secretory glands probably responsible for protective secretions.


Saltbush in bloom  by JB

The individuals are separate males and females (proper term,  dioecious, die-EE-shus).  That’s no biggie,  but the odd thing is, how many dioecious plants have male-female differences other than the flowers?   That is rare in my experience.  According to a USDA publication, the males have longer shoots, softer leaves, faster growth, and earlier seasonal senescence than the females.   Sounds like maybe the males are more “designed” to reach out and scatter pollen, in contrast with females who need more sturdiness and an extended season to make fruits.  Pollination is by wind and by insects.  The small wind-dispersed fruits are on parachutes.


Female flower clusters by JB

Species of Baccharis have an adaptation sometimes associated with salt-tolerance…water-emitting valves called hydathodes at vein tips.   Hydathodes resemble the drip-emitters used in irrigation, flushing out water and anything in it such as excess salt.


Baccharis hydathode by Dr.  Bob Wise, Univ. of WI Oshkosh, with permission. Scanning electron microscope view.

John and I have been watching ants scramble around the Saltbush.  The ants come marching two by two to tend sucking insects.    The sucking insects we’ve seen are aphids and perhaps two species of scale insects.  (Baccharis is the main Florida host for Green Scale.)  Such insects “suck” sugary sap from the host plant.   The sugary goo passes through the lil’ sucker to drip forth from the other end as “honey dew.”   The honeydew can spread and grow black fungi called sooty mold, and some of it follows a more interesting path as ant food.


Ant on Saltbush today.  With scale insects and sooty mold.


Green Scale on the leaf today

That ants crave honeydew and tend its makers like farmers tending cows is well studied, producing conversations about three-way symbiosis: win-win-win.  The plant gains armed guards.   The ants get sweet treats.  And the sucking insects, well, if they are not merely exploited, might get help in dispersal and might be under the protection of their creepy little shepherds.

CLICK to see a similar symbiosis, of all things, on the inside the stem of a different plant.


Posted by on October 28, 2016 in Saltbush, Uncategorized



4 responses to “Saltbush

  1. theshrubqueen

    October 28, 2016 at 7:23 pm

    A favorite native, in this area, these are few and far between. I enjoyed reading about the Saltbush! Happy Friday.

    • George Rogers

      October 30, 2016 at 9:37 am

      Thanks Shrub Queen. Agreed, they are spotty where they grow—complicated some by the preferences of three species. Not very conspicuous when not in flower. How many members of the Aster Family locally can grow into trees? (I can’t think of any others.)

      • theshrubqueen

        October 30, 2016 at 10:43 am

        I am always excited to see one!

  2. Annie Hite

    November 1, 2016 at 2:18 pm

    Love your blog and save them all. I hear you’re going to speak at the FFGC District meeting hosted by the Jupiter-Tequesta Garden Club – I’m a member and am so excited that I will get to meet you and hear you speak.
    As for the saltbush, it took me a long time to identify this on my own after spotting one at Jonathan Dickinson. Am very glad to get expert confimation.


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