Slash Pine and T. rex

18 Sep

Pinus elliottii


This afternoon I just couldn’t decide what to write about, and then in flew inspiration: an e-mail from PBSC Interim VP for Academic Affairs Dr. Ginger Pedersen about a state champion challenger slash pine near PBIA , and an old stand of uncut pines in Dade County.     So I’m now in a pine kinda mood, and that’s a nice way to be.    Long ago in this blog we looked at slash pine, the turpentine industry, and the nasty toxaphene insecticide spin-from that.   Today it’ll just be pretty pine trees.

Pretty pines. Today's pictures by John Bradford.

Pretty pines. Today’s pictures by John Bradford.

Two native pines grace our immediate area, Sand Pine in scrub habitats, and Slash Pine all over the county. Divided into two varieties, the latter species is native throughout Florida and across much of the southeastern U.S., and cultivated worldwide in warm climates for turpentine, pulp, and wood. Variety elliottii is in North and Central Florida and in nearby states. Variety densa, with heavier wood and a fire-resistant grassy stage, is mostly in southern Florida, and their natural ranges don’t overlap much.

Pines are tough and diverse, a hundred species resisting drought, poor soils, and extreme weather from the far north to the equator.   Very few true pines occur naturally in the southern hemisphere (although the name “pine” gets applied to many posers).

Slash Pines in Jonathan Dickinson Park.

Slash Pines in Jonathan Dickinson Park.

Pines have weird wind-dispersed pollen grains with two airbags suggesting Mickey Mouse ears.   The pollen ears possibly help orient the grain for its job of fertilizing the egg in the young cones, which take 3 years to mature.      Anyone who has parked under a pine in the spring has brushed the yellow pollen off the windshield. It comes from small papery male cones that bust apart and evaporate.   The female cones are big and woody, and release wafer-thin windblown seeds from between the scales if squirrels don’t chew the cones up.

Slash Pines maintain fungal root associates. Perhaps sometimes in relation to those symbiotic fungi, the trees often don’t like certain suburban yards, altered water regimes, ozone, over-fertilized soil, alkaline soil, irrigation that renders the soil alkaline, and a number of insect pests.

Many types of trees to varying degrees shed lower branches from the trunk.   Some snap off cleanly, others break irregularly and decay.   Slash Pine is a leader in branch shedding, although the anatomical-physiological mechanisms are unstudied.   Most observers interpret the self-pruning as an adaptation to keep the upper canopy safely above ground fires.   Whether fire induces branch loss directly is unclear. Pines have unusual growth responses to stresses, making stress a suspect in forcing branches to fall.   As another possibility, aging pine needles lose function, so that old ones may fail to keep their branches alive.

pines and sun - Copy - Copy - Copy

Slash pines have additional fire adaptations, such as young variety densa with grassy needles wrapped protectively around the bud, and when older by having fire-resistant bark. Back in the Cretaceous Period when dinosaurs ruled, conifers helped rule, and forest fires became common. Botanist Tianhua He and collaborators have shown fire adaptations in pines to date back into dinosaur days eons before Florida was here to have pine woods.

Pines helped the dinosaurs rule.

Pines helped the dinosaurs rule.


Posted by on September 18, 2015 in Uncategorized


21 responses to “Slash Pine and T. rex

  1. theshrubqueen

    September 18, 2015 at 11:31 pm

    I have been pining for some Slash Pine info! Nice pine pictures. Does anybody around here respect the CRZ of Pines when developing land?

  2. Tom Kean

    September 19, 2015 at 6:57 am

    This is very interesting

    Thank you

    • George Rogers

      September 19, 2015 at 11:50 am

      Thanks – so often the most interesting plants are the ones right in front of us

  3. George Rogers

    September 19, 2015 at 10:36 am

    What is the critical root zone for a slash pine? The critical root “niche” all things considered is probably fairly narrow in several parameters, though wide in moisture fluctuations.

  4. Ginger Pedersen

    September 19, 2015 at 11:44 am

    Very nice! My grandfather always said never buy a piece of Florida land that has no pine trees! It meant that the land was probably flooded or full of muck.

    • George Rogers

      September 19, 2015 at 11:50 am

      Yea—that must be that piece of “swampland in Florida” you buy sight-unseen for your dream retirement home.

  5. theshrubqueen

    September 19, 2015 at 2:43 pm

    Development codes in some places call for 1 foot per one inch of dbh to save the tree this area must be left undisturbed.

  6. George Rogers

    September 19, 2015 at 3:30 pm

    ok thanks,,,pretty skimpy really…

  7. theshrubqueen

    September 19, 2015 at 5:04 pm

    Actually, that is the radius – a 20″ dbh tree calls for a 40 foot undisturbed area. I have done so much land development with this and it does save Loblolly Pines, I would be interested to know about the Slash Pines..

    • George Rogers

      September 20, 2015 at 10:36 am

      Well, that’s better. I’m sure plenty of space helps, or is necessary, but you sure see a lot of slash pines with ample space suffering in the middle of lawns, often chlorotic. A standard explanation is that irrigation water at too a high pH interfering with iron uptake is to blame, and of course they come from naturally low-nutrient habitats, so certain turf fertilization regimes may throw them a curve, not to mention turf fungicides in relation to mycorrhizae conceivably, although I am not aware of research on that. If you look, you can find individuals in urban settings with apparent ozone damage too. By the same token, Slash Pines are cultivated all around the warm world so their overall needs and tolerances may be pretty well documented.

      • theshrubqueen

        September 20, 2015 at 11:38 am

        Yes, all true, I think big and old trees (and humans) dislike dramatic changes to their environments.

  8. Martin

    September 20, 2015 at 8:43 am

    Beautiful, teacher. And perfect pictures!

    There’s nothing more majestic than those old, tall slash pines that have escaped the lightning, lost all their lower branches, been BURNED OVER repeatedly and end up with that huge, flat crown – like those down by the Kimbell Center, eh?

    • George Rogers

      September 20, 2015 at 10:26 am

      Martin, Absolutely…that’s my image of “Florida,” rather than those palm trees and hibiscus on so many Florida-ish logos. Some of those in the park are magnificent, especially against stormy skies. I wonder if the extra-dense wood of our variety has to do with standing up to hurricanes.

  9. Ginger Pedersen

    September 20, 2015 at 3:35 pm

    I talked with a firefighter who worked in Miami-Dade for years and they dreaded when one of the old cottages would catch fire – the wood is so full of sap it can explode and burns very hot.

  10. George Rogers

    September 20, 2015 at 10:56 pm

    You can only imagine—buildings of pine wood must burn in about 10 minutes. I remember as a kid at campfires, pine logs would burn like flares, popping and throwing up sparks.

  11. FeyGirl

    September 21, 2015 at 12:29 pm

    Love the slash pines, and these are gorgeous images! Of course I love the T-rex in there… who wouldn’t? 🙂

  12. George Rogers

    September 21, 2015 at 9:51 pm

    yea, flushed em out of the swamp growling and snorting

  13. Steve

    September 28, 2015 at 10:07 am

    I do like slash pines. A colleague of mine mentioned that this species’ ancestors originated in Central America, and migrated through the Caribbean to Florida. Do you know any truth to that?

    Also, what do pines, oaks, and eucalyptus have in common? Their mycorrhizae. A former professor of mine at UM, Dr. Dave Janos, (who is a specialist in mycorrhizae) conducted a study on fire and and its impact on differnt types of mycorrhizae. He elaborates on this “Ashbed Effect” whereby fire in forested systems (like our hammocks), creates conditions for woodland ecotmycorrhizal specialists such as Eucalyptus (and Pines) to move in. Further explaining why fire is so important to some plant species. Here is a link to his article:

  14. George Rogers

    September 28, 2015 at 11:35 am

    Thanks Steve, Are you familiar with a particularly old stand of large pines in M-D?

    On the FL origins of slash pine, I don’t know the answer. Seems plausible, given that when the species evolved, FL did not even exist, at least in any fashion relevant to pines. All depends on what is meant by ancestors, I suppose—early conifers, or early pines, or direct immediate ancestor to Pinus elliottii, which would beg the question of where you draw the taxonomic line. But the short answer it seems to me, as FL flatwoods habitats transformed from sea bottom to “dry” land, the pine invasion probably came from Central America.

    Thanks for the mycorrhizal link…always interested in any ecophysiology for my physiology class. Will work that info in, with gratitude.

    • Steve

      October 1, 2015 at 7:35 am

      Thanks George. I am not directly familiar with this stand, but I bet it is north of the South Miami area where the soil is less rocky. I have seen some large “sentinels” in some Coral Gables yards. I wonder if it might be the population at the St. Thomas University. I will ask around.

      • George Rogers

        October 1, 2015 at 10:46 am

        Steve, Thanks, George


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