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It’s Vine-Eat-Vine in the Scrub…

08 Jun

Unless you’re a Smilax

Darwinian competition is rough business:  frogs eat flies, snakes eat frogs, hawks et snakes, and Love Vine eats other vines in the scrub.   In case you don’t know Love Vine (Cassytha filiformis), it is that yellowish spaghetti vine festooned all over other plants in scrub and additional habitats. It forms massive tangles smothering and parasitizing all beneath.  

Love vine bothering its neighbors, by John Bradford

Love Vine penetrates its plant victims with little suckers called “haustoria” and sucks out sugar and water. 

Haustoria at work, JB

  Not nice, but it gets ahead in the world.    Love Vine probably came here all the way from Australia, pollinating itself to make the intercontinental hopscotch easier.   Tiny thrips, insects that parasitize the Love Vine, ride in a stowaway space between the fruit wall and an outer covering of fleshy birdfood.  Apparently the birds help the vine AND the thrips get around.   All well and good, but what interested me today is seeing in the scrub that a different vine, Earleaf Greenbrier  (Smilax auriculata), not only seems immune from the Love Vine, but also uses it to rise above the tangle  into the sun.  The invulnerable Smilax climbs up the Love Vine unmolested, and snakes along the top of the Love Vine to enjoy an easy path above all the shade, crowding, and parasitism below.

Smilax ignoring Love Vine. Can’t catch me!

It gets a little more complex.  Another  vine in the scrub (and elsewhere) is Muscadine Grape (Vitis rotundifolia).  The grape resembles Smilax in overall habit, stem diameter (when in scrub), climbing ability, leaf size, small plain clustered unisexual flowers, and making “bunches of grapes.”   Unlike Smilax, however, the grapevine falls prey to Love Vine.

Above: Grape is not immune!

Smilax comes out on top

Why the difference?   Most woody plants have their water-conducting and sugary-sap poorly protected just under the bark.  Easy pickings for creepy Love Vine.    But Smilax is different:   its stem is built like cables within cables.   (Because It is a monocot if that matters to anyone.)  If you cut across the stem  and look end-on, the plumbing is deep within the stem and surrounded by a hard  protective sheath.     No parasite is going to break into that!

End view of Smilax stem magnified. The green circles surround the sugar pipes. The big blue rings circle the protective sheath. The large open ends within the sheaths are water pipes.

Don’t get me wrong. No suggestion here that the Smilax stem internal structure is a special adaptation to block Love Vine specifically (although it might have a lot to do with protection in a broad general sense). So do those thorns. Think of it as a chance thing…lucky Smilax winds up in a habitat with a stem structurethat just happens to offer an advantage against would-be competitors such as grape, or maybe species long-gone because of not having the “right stuff.”

 
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Posted by on June 8, 2024 in Uncategorized

 

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Devil’s Claw Will Gitcha!

04 Aug

Devil’s Claw

Pisonia aculeata

Nyctaginaceae

Here’s a trivia question for flower-buffs: What do Devil’s Claw Vines in the forest, Bougainvilleas at the hotel, Four O’Clocks in the garden,  Blollies on the dunes,  Beach-Peanuts on the sand, and Red Spiderlings in the rough have in common?

You guessed it—they are all members of the Nyctaginaceae family.  And that gem underscores the importance of learning plants by families, not just one at a time.  If you know some of these species, do you see the family resemblance?   The Devils Claw leaves and branching pattern look like Bougainvillea.  A lot of Nyctaginaceae have colorful bright reddish-purplish pigments—Bougainvillea, Four O’Clock,  Beach-Peanut,  Red Spiderling,  even the Blolly fruit.    The colorful “flowers” have no petals.   The colorful parts are bracts, that is, modified leaves associated with the flowers.    There are also sepals, and the fused sepals can make a tube, this often tightly enclosing the one-seeded fruit.

In today’s plant as the sepals enclosing the fruit have odd rows of protruding glands to help the fruit cling to passing animals.  They are are gummy-sticky.

Recurved claws

The name Devil’s Claw  comes from scary back-curved spines.   We know the pain from recent ankle-bleeding experience.    But why have curved spines for self-defense when straight bayonets are more to the point?     Perhaps reverse-curvation helps the vine cling to its host trees.  Hurricane country,  after all.  Under ideal conditions, Devil’s Claw can graduate from its lowly clinging vine status to full-blown treehood.

The plants are either male or female, that is, they are dioecious, and the male and female flowers differ.   The male flowers are bowl-shaped and yellowish;   the females  are narrower,  more constricted, with a comical brushy stigma resembling the tuft on Jeff Dunham’s friend Peanut.  (Huh?  Just Google Image it.)

Male flowers

Devil’s Claw occurs throughout much of the American Tropics, including South Florida, and now extends around most of the warm-climate world,  no doubt due to artificial introductions.  (This post is a collaborative effort by John Bradford and George Rogers on the east shore of Lake Okeechobee.  JB took today’s pictures.)

 
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Posted by on August 4, 2011 in Devil's Claw

 

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