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Dreamy Drifts of Pink

11 Dec

Mexican-Clover

Richardia grandiflora

Rubiaceae (Coffee Family)

Returning reluctantly to my office just now from Tropical Smoothie with my Limey Blimey smoothie,  heavenly meadows of pink in the athletic field soothed my troubling mind, thanks to a member of my favorite Dicot family, the Coffee Klatsch (aka the Rubiaceae).   Typical of life here in Misnomer Meadows, “Mexican-Clover”  is no Clover and it is not natively Mexican.  Thus for the sake of accuracy some call it Fairy Cups.  If you live in South Florida you have seen the pink cloud in the median strip.  Some observers say it looks like snow, but those must be Floridians who have never actually seen snow.  And just like snow, this weed’s not native to South Florida.  South America is home.

Richardia grandiflora Fairy Cups by John Bradford

Richardia grandiflora Fairy Cups by John Bradford

The genus Richardia consists of about 15 species ranging naturally from the Southeastern U.S. to Argentina, with some escaped in the Old World.  The original native U.S. representation is a messy question beyond the scope today.  Some of the species can be tough to distinguish, even in our normal “Treasure Coast-ish” botanical radius.  (Handy notes below.)

Any fool can distinguish Richardia grandiflora at 70 mph in the highway median.  Seems like cars, lawn mowers, and Global Warming might be expanding its range northward, at least as far as arctic Gainesville, and motivated searchers could probably pinpoint more-northerly patches.

How does one pretty weed take over vast areas of lightly maintained turf as a monoculture?  I have no single answer, but here is a bundle of silly notions:  1. The Coffee Family is a talented weed family.   2. The mat sprawls low.  I dug one up this morning.   The underground rhizome bears roots all over itself, and it sprouts, sprouts, and sprouts near or even below  the ground surface.   Mowing clearly prompts branching from way down low,  allowing this Dicot to pose as a Grass.   3. The weed is mighty drought-tolerant,   happy on sterile soils, and probably nematode-proof (just guessing based on a related species).   4. Each fruit splits into a variable number of bumpy little “seeds.”  The “seed” production of a single patch is infinite, and all those little crumbs build up a seedbank.  5. And the big question, are Richardias alleleopathic?  That is, do they make natural herbicides to suppress competition?    I do not know.  They look like it, and seem like a study waiting to happen, along with the dormancy characteristics of the fruit segments.

Mexican-Clover has opposite leaves, and between their bases is the hallmark of the Coffee Family, an “interpetiolar” (between the petioles) stipule.  The stipule is fringed on top, and basally forms a cup around the node where new buds form.  Although often in the Coffee Family the stipule functions to draw symbiotic ants, or to protect the terminal bud, my guess is that in Mexican-Clover the stipule catches water and coddles the sprouting buds nestled like baby kangaroos in the stipular pouch.   The stipule is so fancy, I took a picture of one today for reader stipular titillation.

The stipule is fringed on top, and encases the lateral buds (future branches).  Rising at 45 degrees on each side are the petioles (leaf stalks).

The stipule is fringed on top, and encases the lateral buds (future branches). Rising at 45 degrees on each side are the petioles (leaf stalks).

The fairy cup flowers look like classic butterfly-pollinated blossoms, and butterflies visit, along with bees and other insects. A big patch of MC can be bug-lively.  Each flower head is a sponge in a cup, with the maturing fruitlets embedded deep in the moisture.  The flowers are packed together tightly with their sepals rising vertically as a collective water trap in the center, reminiscent of some Bromeliad tanks.  Bringing a specimen in this morning after a wet night, the flower heads left puddles of water on the microscope stage.

Being a lawn weed, Mexican-Clover raises the boring question, over and over, about  “what do you spray on it?”  Now please understand, as a pesticideophobic, lunatic fringe nature-nut, this question is not my cup of tea.  TC Natives is not for squirt-gun how-to-garden advice.  Yet turf herbicides interest me from the dark side.  Noodling around Google reveals many recommendations to use Atrazine to get those ugly Fairy Cups out of your lovely yard.

Two bumpy fruit segments. The structure below the twin segments is the semi-persistent calyx (set of sepals).

Two bumpy fruit segments. The structure below the twin segments is the semi-persistent calyx (set of sepals).

So now a moment on the Atrazine soapbox.  That is bad stuff unless you like deformed amphibians.  Atrazine is one of the most-used turf herbicides in the U.S., although alternatives might replace it.  Perhaps you thought the U.S. had already pretty much eliminated chlorinated pesticides, such as DDT, Chlordane, and Lindane.   Well, is an herbicide a pesticide?  I’d like to know, because we still have plenty of chlorinated herbicides, the two main examples being lawn poisons we pay technicians to infuse into our personal environments, 2-4-D, and Atrazine.  2,4-D is a chlorinated (auxin) hormone mimic.  And Atrazine has a slight molecular similarity to the fertilizer material urea.  Plants take up Atrazine from the soil as they might take up urea.  (Where does the rest of the Atrazine go?)  Atrazine is so water-soluble it contaminates waters worldwide.  And it is implicated ominously in environmental-health issues.  Rather than rant, I’ll pass the buck:  see what (the controversial) Professor Tyrone Hayes at the University of California has to say on this topic.    CLICK

Call me Bud.

Call me Bud.

—————————–

Notes:

Distinguishing the species of Richardia in our normal activity radius, especially R. scabra and R. brasiliensis, can be a pain in the grass.  By the way, the “handbook” features don’t hold much water.  Professor Alexander Krings in North Carolina had the same pain, and did something about it, compiling a guide to this problem.  Paraphrasing his work, try this:

Richardia grandiflora is easy: It is the only one with the (usually pink) flowers over 12 mm long.

Richardia brasiliensis:  Stems bristly evenly from tip to base, top of leaf evenly hairy,  and the inner face (narrowest face) of the fruit segment is broadened (Brazil is a broad country).

Richardia scabra:  Stem becoming more or less bare toward base.  Top of leaf hairy primarily near the edges.  The smallest face of the fruit segment  narrowed to a narrow groove.

(The kangaroo pic was stolen from Down Under.)

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8 Comments

Posted by on December 11, 2012 in Mexican-Clover

 

Tags: , ,

8 responses to “Dreamy Drifts of Pink

  1. Mary Hart

    December 14, 2012 at 4:22 am

    Fascinating stuff!

     
  2. George Rogers

    December 14, 2012 at 2:31 pm

    Hello Mary, Just got back from a beautiful trip to a nearby State Park, Savannas State Park. 70 degrees, sunny, fragrant breeze, beautiful flowers. Found na edible passionvine growing escaped on a long-abandoned farm site, so John and I enjoyed some passionfruits. He took pix, so might be next week’s topic. Wish you were here for the passionfruit party…George
    (That’s as wild as my partying gets.)

     
  3. Kristi Moyer

    December 18, 2012 at 7:59 am

    Hi Dr. Rogers! Yeah this Florida snow has got to go. Thus far, we leave it where we have no control and pull it where we stand a chance. It invaded my prairie here at Pine Jog and has taken over my Mimosa strigillosa dune while I was away on maternity leave. I guess at least it is pretty to those who know no better.

     
    • George Rogers

      December 18, 2012 at 9:01 am

      Hi Kristi, Oh geez, Richardia must be a nightmare in the prairie! Haven;t been down that way lately but will make a pint. I think our technician David Diaz who is starting a small native plants perennial garden here is going to come try to learn from the Master. Make David pull a few hundred weeds in exchange for advice.

       
  4. Beth Burger

    September 10, 2013 at 4:33 pm

    Hi George, truly, truly love your blog… wow, discussions of our lowly local plants….thanks!!! and still use your floridagrasses.org a lot. Spermacoce verticillata is another non native Rub here that I see making its way into natural areas including wetlands, and I wonder about controlling (i.e. herbiciding) it because of all the insects buzzing around it. I worry about what all the bugs will do without it.

     
    • George Rogers

      September 11, 2013 at 7:00 am

      Hi Beth, Nice to hear from you! Would you vote too for Spermacoce verticillata to be the most successful and most integrated weed in S FL? Take it away and you’d see the blank space from a plane! I’ll bet you are right about the bugs.

       
  5. Stefano Ferrari

    July 19, 2017 at 2:20 pm

    Dear Doctor Rogers,I am very interested by your post about Mexican clover. I love groundcover and I am always looking for mat forming plants in order to test it for my climate (I live near the sea in Italy).

    There is any chance to obtain some seeds of Richardia grandiflora? Thank you anyway for your reply.

    Best regards,

    Stefano Ferrari

     
    • George Rogers

      July 19, 2017 at 2:31 pm

      Stefano, I’d be glad to help you, but careful careful careful…this plant will take over the word. If you were to introduce it successfully it is likely to get out of control as it is in Florida. It is such an aggressive weed my guess is if it would grow in Italy it would be there, and perhaps is already. I’m pretty sure it has no tolerance for cold.

       

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