Who Eats Those Beautiful Scrub Fruits?

30 Sep

Sandyfield Beaksedge

Rhynchospora megalocarpa


Friday John and George wandered through the several habitats at the Haney Creek Trail in Jensen Beach Florida, where scrub forms a patchwork among depression ponds, streams, pine woods, and weed areas—a rich place to count species, and a pretty place to enjoy Liatris, Polygonella, Goldenrod and much more in colorful autumn bloom.

The "seeds" on Rhynchospora megalocarpa are huge, showy, and plump by sedge standards. (By JB)

The “seeds” on Rhynchospora megalocarpa are huge, showy, and plump by sedge standards. (By JB)

All the floral beauty distracts the eye from the more subtle fruiting beauty.   Turning the attention to the fruits and seeds raises the question of who eats what in the scrub.   What are the ecological relationships in the scrubby food chain?  (Many critters visiting the scrub are not restricted to that habitat.  But bear with me.)   Pygmy Mole Crickets eat algae growing in the sand.   Probably most of the smaller reptiles live on scrubby arthropods.  The blueberries look like birdfood to my casual eye.  No doubt the Gopher Tortoise goes for Gopher Apples.  Among the more conspicuous and intermittently abundant fruits are the acorns.  I just read that a single Scrub Jay can store several thousand acorns per year.   The cute Gopher Mouse (Florida Scrub Mouse) is an acorn eater too.   CLICK

But what do they substitute when the acorns are few?

And that is all the lead-in to a puzzling question.  Who eats the big, glossy, showy “seeds” (achenes) on Sandyfield Beaksedge?  This is one of the world’s most under-studied plants.  When you hear discussion of scrub plants you hear all day long of the various oaks, scrub-rosemary, sand-pine, lyonia species, innocence,  and others, but whoever mentions Sandyfield Beaksedge?  A large, tough bright green sedge scitter-scattered abundantly on that sun-baked sugar sand.  Aren’t sedges supposed to prefer wet places?  (Not all of them.)     Sandyfield Beaksdge represents the large, fascinating, locally diverse genus Rhynchospora,  whose name translates loosely as “beak seed.”   (When you have rhynoplasty you have a “beak job.”)   The beak is on the seedlike fruit.  The beak size and shape varies among the local Rhynchospora species, from almost scary to barely visible.  The genus is in every Florida habitat from standing water to the dryiest scrub.  Sandyfield Beaksedge occurs throughout Florida and into other southeastern states.

In Sandyfield Beaksedge the beak looks like the cap on an acorn, making the entire little “mini-nut” resemble a shrunken acorn, enormous and ostentatious by Rhynchospora standards.  Maybe the achenes are oversized due to a simple need to provide the seedling with extra protection and nutrients in the stressful habitat, but they are too colorful and eye-catching, and prominently displayed for merely that.

R. megalocarpa 6

Thus every time I see a cluster of the large, showy, glossy little “acornlets” on the Sandyfield Beaksedge it bugs me wondering who relies on them for food.  I’m ready to go sit in the scrub all night long with night-vision goggles and watch.  Like little nuts, the SFBS achenes are hard and dry, not squishy and sweet.  I wonder if the true scrub acorn-eaters—the Florida Jay, the Gopher Mouse, and other furry little rodents use the mystery fruits  as substitute acorns as a between-meal snack.  Interestingly, the fruits start out elevated on a wand, and as time passes  the wand bends down to ground level, placing the fruits within easy reach of Mickey and Minnie.


Posted by on September 30, 2013 in Sandyfield Beaksedge


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4 responses to “Who Eats Those Beautiful Scrub Fruits?

  1. Steve

    September 30, 2013 at 8:16 pm

    I think you are right on about rodents eating them. My bet is doves, or big beaked things like cardinals, also eat it, although I’ve never seen either consuming it. Maybe the passenger pigeon was once a major seed predator…

    What’s weird is I came to this thought while reading Guns, Germs, and Steel by Jared Diamond. One of his claims is that there are few grasses with large seeds in North America, and that was why people here were slower to cultivate grains. I know it isn’t a grass, but I wonder if R. megalocarpa would make a nice bread?

  2. George Rogers

    September 30, 2013 at 8:50 pm

    At least on-line, I can find no reference to anything eating or storing it…which is weird given the size and coloration. Sure,. maybe doves or passenger pigeons. Have you seen the speculations about re-constituting PP’s from old DNA? Very Jurassic Park, but the pigeon speculations seem to have special oomph. At least to a gullible guy like me. Interested to try some of the achenes in terms of different manipulations in relation to germinaton. We noodle around a little with such things at our campus plant nursery, and at least two of our technicians enjoy trying native seeds. Setting corn aside, not much on grainy grasses from the New World, oddly enough, as you noted. But I’ve been fascinated forever by the Iva “grains” developed as over-sized cultivars before the corn-bean-squash invasion. Those SFBS achenes do look wholesome and nutritious. I did “eat” one last Friday. Needs a little syrup!

  3. Mary Hart

    October 1, 2013 at 4:25 am

    I would suggest that the most effective way of sussing out what animals might feed on this “nut” would be to set up a camera triggered by movement, so you get a picture of what arrives. Here in UK we’ve had some brilliant TV programmes showing, for example, what critters might arrive at a feeding station in a garden. It’s a lot easier than sitting still for hours waiting for something to happen!

  4. George Rogers

    October 1, 2013 at 9:17 am

    You know, trying that is not out of the question. They sell small inexpensive motion-activated outdoor cameras for hunters to find game, and I wonder if such cameras are sufficiently sensitive for activation by birds and rodents. Might go so far at least as a little Internet research on the topic. My wife is a wildlife biologist (now teaching Biology) who long ago studied Spermophiles, including thier table manners. That ancient history might be the underlying reason I’m drawn to the sedge fruits. That said, she’d proabably agree to acquiring such a camera if affordable just for the fun of it. One night years ago I sat out all night in a blind with long-distance-activated camera in a favorite owl spot. No owls. Long nite.


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