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Polygonella

12 Sep

Wireweeds, Jointweeds,  Octoberflowers

Polygonella species

Polygonaceae

Two weeks ago John and George botanized a morning away in Jonathan Dickinson State Park near Hobe Sound.  The open sand areas looked like foam on the sea thanks to Octoberflower (Polygonella polygama).  This week we had chores in and near  Savannas Preserve State Park at Jensen, where another Polygonella,  Stout Jointweed (P. robusta) made the sugar sand whiter.  It is a Florida endemic or nearly so.  These and additional Polygonellas help keep Florida beautiful with their delicate mostly-white bountiful blossoms, which are on separate male and female plants in Octoberflower, but either bisexual or mixed male and female on single plants in Stout Jointweed.  The flowers of both start out white and turn to pink or rose or deeper shades, creating  impressionistic  color drifts in dense Polygonella meadows.

Octoberflower in September (by JB)

Altogether there are 11 species of Polygonella, all of them in the eastern and southern United States, most represented in Florida.  As a group, they tend to like dry sunny sandy places,  such as open areas in scrub, sometimes sandhills, or disturbed places.

Outside of our usual haunts, Polygonella basiramea and P. myriophylla are federal listed endangered Central Florida scrub endemics.  Polygonella myriophylla maintains a clear zone around itself by emitting natural herbicide(s).  This “allelopathic” ability probably occurs in other species as well, but rare and endangered species attract research.  Our Treasure Coast-ish species have bare zones around them too. Do they poison the competition?  Or do they merely grow the hot bare sand  where others fear to tread?  Or do they take advantage of the allelopathic “moats” of naturally herbicidal third parties, such as Florida-Rosemary?  All that would be fun to study.

Take a close look at a Polygonella…hey, there’s something “wrong” with that plant.  Oh, I know, the branch points are between leaves rather than immediately above the leaf-stem junction as in the rest of the plant world  (The branches originate normally but remain fused in part to the stem giving the illusion of arising midway between leaves.)  Knowing this, now you will never have trouble recognizing a Polygonella.

This shot shows the brown ocreas (cigar bands) at the places where leaves are or were, and the branching oddly spaced between the leaf attachment points. In normal plants bracning happens at the leaf attachment points. (By JB)

Also noteworthy, just above each leaf attachment point a cigar band membrane called an ocrea surrounds the stem.  The ocrea is characteristic of the Polygonaceae Family and turns up also in the big kinfolk:  Sea-Grape and Pigeon-Plum.   In some species., including our Stout Jointweed, the ocrea has long bristles on its top edge.

Faced with the heavenly flora displays of Polygonellas, the question must bas asked, what pollinates those lacey flowers?  Multiple insect species visit, but the interesting one is the Polygonella Bee Perdita polygonellae.  It is a Polygonella specialist, a single insect species dedicated to a genus of plants.  Which came first, the Polygonella or the bee?

White on white, P. robusta this week (by JB)

Kwick Key to the Common Treasure Coast Species

(The English names are inconsistent and messy.)

1. Ocrea with no bristles…2

1. Ocrea with bristles…3

2. Plants essentially leafless when flowering…Slender Wireweed,  Polygonella gracilis

2. Plants with leaves shaped like little canoe paddlesOctoberflower, Polygonella polygama

3.  Leaf blades usually < 1.3 mm wide,  the margins not translucent…Fringed Jointweed, Polygonella ciliata

3. Leaf blades to 2.5 mm wide, the margins translucent…Stout Jointweed, Polygonela robusta

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7 Comments

Posted by on September 12, 2012 in Jointweed, Octoberflower, Wireweed

 

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7 responses to “Polygonella

  1. Mary Hart

    September 13, 2012 at 3:29 am

    What beautiful plants.

     
    • George Rogers

      September 13, 2012 at 7:40 am

      They truly are, especially in great masses like clouds. You just can’t capture the entire “meadow” in a photo, not even John. They smell good too.

       
  2. Martin

    September 13, 2012 at 7:59 am

    This and the little bitty wireweed are just about my fav-o-rites. For one thing, when they bloom, I know the summer is about to end!

     
  3. friedovaArt Goldsmith

    January 22, 2014 at 5:52 pm

    Hi George. I found a single Polygonella robusta (which, in the book I consulted was called Sandhill Wireweed) at Seabranch State Park, on December 20th…not too far from Jonathan Dickinson. Have you seen others this late?

     
    • George Rogers

      January 22, 2014 at 6:01 pm

      Well, not to my recollection, but that doesn’t mean a whole lot. There’s a copy of Taylor’s FL Wildflowers at my elbow—let’s see, he gives the flowering time as March-November. So we’re in the middle of non-floweirng. I wonder if the flower thinks it is March already, or still November.

       
      • Art Goldsmith

        January 22, 2014 at 7:11 pm

        Thanks. I have been using Taylor’s book as a reference, and saw the flowering period. I have learned to not trust “flowering period” for plants here. Would you be able to help ID 3 more I have photographed, but have not, as yet, IDed? 2 are from Blowing Rocks Preserve on Jupiter Island, the third s from Oxbow Center in Port St. Lucie.

         
      • George Rogers

        January 22, 2014 at 9:44 pm

        Right. I often have a working rule–it is remarkable how often you can find a flower or fruit “out of season” if you try. Sure, I’d be glad to look at photos. My office e-mail is rogersg@palmbeachstate.edu.

         

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