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Saw Grass

Saw Grass

Cladium jamaicense

Cyperaceae

John and George failed to hit the wilderness this week for diverse reasons, including a mandatory Friday campus meeting for George, and John completing the revision of our grass web site  CLICK

The website adventure has resembled crossing the Everglades in a Speedo,  bled by typo mosquitoes, wrestling tech support pythons, and sliced raw by Sawgrass.  John did 90% of the work, and the new revision is a breath of fresh air with better info, old editorial sins corrected, updated photos,  and improved performance.   In honor of the occasion, today’s blog must of course be Sawgrass.  SAW HERE

It is the sworn duty of anyone writing about Sawgrass to point out quickly that we’re talking about a sedge, not a grass.  The name is not 100% misnomer though, the “grass” saws with gusto.

All photos today are Sawgrass by John Bradford.

All photos today are Sawgrass by John Bradford.

When I think of Sawgrass, I think of the Everglades or maybe picking up cool kicks at 40% below retail at Sawgrass Mills.  SHOP HERE  The big sedge is not just a Florida possession however.   It ranges from Virginia to Texas and into the West Indies;  after all, the name is “jamaicense,” not “floridacense.”  And, oddly, there is a population in Hawaii regarded as indigenous.  Sawgrasses get around.  The “seeds” (achenes) float, and they mature a little fleshy presumably promoting bird dispersal.  With species borders debatable, there are Cladiums from Mexico to northern Canada through Europe all the way to Australia.  (CLICK for one classification.)  Cladium mariscoides, a more-northern species with harmless foliage ventures as far south as North Florida.

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Beyond the floating fruits, how does one species fill vast areas, quickly and competitively after fires and hurricanes?  Like many sedges, Sawgrass has rhizomes protected in the moist soil for spreading and regeneration, ho hum.  More interesting is an ability that crops up here and there among  sedges, formation of baby plantlets in the inflorescence, not from seeds but clones of the mother plant—pups or bulbils.  You can see similar clonal babies at the tops of many Agave plants or on “Walking Iris.”  Sometimes the babies take root when their inflorescence bends to the ground, allowing the sedge to “walk” across the land.

Cl_jamaicense3

The sawtooth leaves give today’s plant its reputation as a bloody gauntlet to traverse.  But why do the leaves have those teeth?  The kneejerk answer is to deter eating, but maybe—just a hunch—there’s more to the story.  What’s the biggest threat to a plant that fills acres of wetland?  Herbivory?  Maybe, but competition from surrounding vegetation, even other Sawgrasses, is conceivably a more pressing issue.   Can those infamous leaf margins slash adjacent vegetation as they lash about  in the wind?

Sawgrass is chiefly a freshwater species with limited salt tolerance.  As saltwater intrusion boosts salinity in some habitats, Sawgrass loses market-share to more salt-loving competition.

The famous competitive threat to Sawgrass is by Cattails which have taken over in places.  A much-discussed contributing  factor is artificially high phosphorus levels from pollution entering the naturally nutrient-limited Everglades systems, tipping the competitive balance.  But life is never simple.   Cattails and Sawgrass share an adaptation to flooded soils – air channels called aerenchyma (air-EN-caw-maw) in the roots bestowing upon both the super power of flood tolerance.   But according to research, Cattails have greater tolerance, and are perhaps more robust to soil toxins.  Cattails are favored, it seems, where water is impounded deeper and longer than Sawgrass prefers.  Of course you could write a book about disturbances to marsh ecosystems and consequences to the species balance.  Chapters in the book would concern salinity, nutrients, toxins, water levels, and fires.  But all of that may be subsumed under the final chapter:  Sawgrass marshes are predominantly coastal, and sea level rise from Global Climate Change may have the last word.  Why worry about a few cattails?

 
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Posted by on March 16, 2014 in Saw Grass

 

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