Author Archives: George Rogers

Hypoxis juncea (and similar species)

Hypoxidaceae (not a true grass)

John and I wandered all over Jonathan Dickinson State Park on this hot sunny day working on photography…and on the railroad.

John risks his life for that perfect shot!

The itinerary took us through an area burned nine days ago.   CLICK TO SEE THE BURN   Mostly charred remains and blackened earth.  Amid the ashes is Yellow Stargrass in full defiant bloom.   Didn’t it burn up?  Yes,  yet up and abloom after a week.    Many species, mostly monocots,  blossom after fires.

Observers may attribute enhanced flowering after flames to the blaze removing competition or recycling nutrients.  Probably so, but there has to be something more subtle, physiological, and immediate.       Improved soil conditions don’t likely bring forth blossoms in 9 days or less.   Some burned-over species are up and flowering the next day, Bulbostylis, also found in the Park.     Fire-stimulated blooming occurs sporadically in diverse fire-habitat species.   Combustion somehow causes a flower-inducing signal, probably a hormonal reaction.  An exact mechanism is not known, but the gas ethylene is the prime suspect.

All flower pictures today by John Bradford

Ethylene is a component of smoke, and the gas is also a plant hormone with several known physiological functions, one of them being to switch on flowering in many species. It serves that way commercially in  pineapples.  Could fire-adapted plants have “learned” to harness the ethylene release from a passing fire to get ahead of the curve in recovery?

That Hypoxis juncea gets a kick from fire was known to iconic Florida botanist John Kunkel Small.   Far more recently, biologist Alan Herndon, studying two Hypoxis species in South Florida, found not only that fire brings forth flowers fast, but also more flowers per stalk.  Moreover, curiously, that flowers post-fire tend to be sexual, whereas  fire-free flowers tend to shift to be asexual (cleistogamous) cloning the parent plant rather than the birds and bees.   Fire time is gene mixing time.

Hypoxis juncea and other Hypoxis species have a secret underground tuber.    I’ve read of a correlation between tubers and fire-stimulated blooming.  The tuber is a chemical factory, resulting in fame, glory, hype, and hope for species of Hypoxis as medicinal plants, a little in North America and a whole lot in Africa, where much Hypoxis grows.

These plants have major history in traditional remedies for to many ailments to list.    Their role in modern over the counter remedies comforts many afflictions.   And they’ve crossed the threshold into modern medical research where they may save the world, or flop.

The star of the brew is a sterol called hypoxoside, which releases a component called rooperol into the human digestive system upon ingestion.  Rooperol seems to bolster the human immune system.   This and similar observations led to a wave of marketing Hypoxis in South Africa as a super duper tuber,  often called “African Potato,”  with packaged medicines derived from it.   Rooperol became a wonder drug, especially for prostate trouble, cancers, and HIV.

Although there may be promise, the hype and hope bypassed research to the point of political trouble.   The South African government advocated taking Hypoxis-based drugs for HIV,  you might say in place of established effective antiretrovirals.  Ineffective medication placed HIV patients at increased risk, and set off heated political disagreement in South Africa.

Hypoxis tuber.   “Fire her” refers to the South African Minister of Health who angered critics by advocating Hypoxis, African Potato (Montato) for HIV. (Cartoon by John Curtis, from Y. Singh, Univ. of Pretoria, Ethnobotany of Hypoxis)

Syngonanthus flavidulus

Eriocaulaceae

An appealing aspectsof the southern edge of Jonathan Dickinson State Park along County Line Road at Tequesta, FL,  in addition to the secret James Bond Rocket Tracking Spy Station, is the whitest, sugary-ist, hottest, driest scrub sand, complete with dunes, and with wet spots ranging from moist depressions to a mighty fine lake complete with otter doing what he otter.   All so splendid!   Thus hard to pick one plant to feature.

Syngonanthus flavidulus.  All local photos today by John Bradford.

Well, ok, pretty among the beauties is a curious species straight from Mars…Yellow Hatpins.   White shoebutton flower heads glossy yellow beneath on needle-thin straight stalks rising from basal rosettes.    The white flower heads have golden yellow scales coating their undersides.  The ecology of this and related species relative to light, heat, air, and water would fill a book, I’ll bet, if anyone wrote or read it…strange life-form in an extreme habitat.

Yellow Hatpins favorsthose low damp depressions scattered in the scrub desert.   Syngonanthus is a big group in Africa and South America, dwindling northward to our lone species in Florida and nearby states. (There are additional similar species here in other genera.)

That distinctive golden glow (flavidulus) under the flower heads is the stuff of an industry in Brazil where modern Rumpelstiltskins weave Syngonanthus nitens, Golden-Grass, into gold.

CLICK for gold

Those white heads  resemble those in the Aster Family, but Syngonanthus is about as unrelated to Asters as botanically possible.  The similarity is convergent evolution.  Each head holds hundreds of separate male (pollen) and female (seed) flowers.

The heads closed.   Humid?

Our species has perhaps never been studied in-depth, but similar ones have in Brazil.  Contrary to some earlier assertions, pollination  is mostly by a broad array of tiny insects, including flies, beetles,  and bees.  Doesn’t the fly shown below seem perfectly designed for the job?!  (photo from Carlianne Ramos and collaborators, Annals of Botany 96: 391. 2005.)

A nose for the job

Biologists Aline  Oriani and Vera Scatena studied Syngonanthus elegans.  They found one of those little secrets of nature so easy to overlook.  The flower heads open by day and close at night following the humidity levels.    Those golden scales encupping the head have thick-walled absorbent cells on the undersides.   When it is humid (night) the expandable walls soak in moisture, swell, push the scales inward, and close the head.  When the same cells dry (day) they shrink, pull back, and let the sunshine in.  And now the mystery of nature:  when the head closes it lodges by night little beetles who reportedly pollinate the flowers by day.  Do the beetles get a motel room in exchange for pollination services?   What do they do in that dark room?    Anything like that going on in Jonathan Dickinson Park?

Crocanthemum nashii  (Helianthemum nashii)

Cistaceae

[Useful note:  Helianthemum (Old World) and Crocanthemum (New World) are closely related, traditionally interpreted as a single genus. There are over 100 species.]

Today John (photomaster) and George (umbrella holder) continued a photographic project in Jonathan Dickinson State Park.    John is developing  panoramic images showing highlights of tour beautiful  park.   CLICK   Zoom in, pan around.

Frosty on the burnin’ sands, as they looked today.  (All photos this week by John Bradford)

On those fire-scorched sun-baked dunes grows a natural garden of wildflowers, most of them yellow.   Delicate yet bright and vibrant today was Frostweed, Crocanthemum nashii, better known as Helianthemum nashii.   The floral beauty of the “rock-roses, showy species of Helianthemum,  have made them commercial horticultural delights.   Most of the Helianthemums grow in hot, sunny, arid nutrient-poor habitats, making their curious subterranean relationships research-worthy.  Some hook up, for instance, with desert-truffle fungi.   Some  share a fungal internet with oaks, which demonstrably benefit from the linkage.

That’s interesting, given that today’s pretty little flower grows on the world’s most sterile soil, often among oaks.   Some species, perhaps all,  Crocanthemum–Helianthemum species have a gelatinous covering on their seed coats. The gel houses fungi, which biologists in the 1950s and 60s interpreted as gifted to the seed from the mother plant to help nourish the youngster, especially with Vitamin B1, thiamin.  Botanists in the 1970s brought that intergenerational fungus-among-us into doubt, although the tagalong fungi could perhaps establish relationships with the roots.    Alternatively the fungi could merely be opportunists digesting the jello; then the main function of the goo could be in seed dispersal, or more likely to help with establishment in the arid habitats.    Perhaps the best interpretation, not original with me, is the Mother Site Advantage, which is:  the safest approach is to “stick around” Mom’s proven safety zone if suitable habitat elsewhere is spotty and widely separated.

Now move aboveground.  First of all, the name Frostweed.  Well, with their white hairs the plants look like a frosty mug.   But don’t jump to conclusions!  They also reputedly make “frost flowers,”  i.e.,  pretty ribbons of ice at the stem base on freezing mornings.  So you decide why to call them Frostweeds.  Personally, I suspect the name originated with the hoary-looking foliage, and then the icy handle led writers into over-attributing our plants with frost-flower proclivities?    Many plants do this,   most notably, Verbesina virginica, sometimes dubbed Frostweed itself.  That could engender confusion.

The hairs on the leaves and fruits presumably reflect that killer sand dune sun, although thwarting leaf eaters and maybe even catching/retaining water are possible as well.   (The related and likewise locally native Crocanthemum corymbosum has the leaves notably darker green on top, and the fruit capsules is hairless.)

Crocanthemum nashii is almost restricted to Florida.  Yet those who like to wonder,” how did that happen” might ponder a small geographically isolated population yonder in southern coastal North Carolina, separated from the general population by Georgia and South Carolina.

One final oddity.  The showy yellow flowers attract diverse pollinators, but that’s not enough.    The plants have a second way to make seeds.   Later in the season (C. nashii) or at the same time (C. corymbosa), in addition to those regular open flowers, come small, closed non-showy (cleistogamous) blossoms that quietly self-pollinate out of sight and out of mind.   Differences, if any,  in the gel-covers and germination characteristics of seeds derived from the two flower types might make an interesting study.

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Note:  To dig in on the oak relationship, start here

Epiphytes and Vines Have No Scruples

[Vocabulary help: An epiphyte (EPP-ah-fight) is a plant that grows sitting on another plant.  A so-called “airplant.”  Many aroids, bromeliads, ferns, lichens, liverworts, mosses, orchids, and others can be epiphytes.]

This morning John and George toiled way up high in the sun, on the Hobe Mountain (sand dune) tower in Jonathan Dickinson State Park working on a photo project.   While aloft it was impossible to ignore our similarity to plants perched likewise with a view:  epiphytes and vines.    We were human epiphytes.

Epiphyte-eye view, as seen from the JD Hobe Mountain Tower today

On the dune in the early morning there was perfume in the air.    Fragrance on a burned  sand dune with dead charred trees?   Yes, coming from flowering Cat Briar (Smilax) vines taking advantage of the bare tree skeletons to cover the limbs with replacement foliage, absorbing the orb using someone else’s  woody infrastructure.  That’s how vines roll.

Smilax repurposing dead tree.

In the event of fire, our Smilax auriculata dies back to a hunky rhizome to rise again…free of competition.   I like the fragrance of our Smilax, although the genus more broadly strikes some sniffers adversely.  Many Smilax species belong to “Section Coprosmanthus,” Latin for outhouse-flower.     Funny thing about Smilax, the individual vines are separately male (pollen producing) or female (fruit-making).    Weird, isn’t it, to “waste” individuals as making pollen but no fruits?    (But come to think of it I’m a wasted human making no babies.)  Perhaps in a massive vine making thousands of crowded flowers the sexual separation is necessary to force crossing where otherwise self-pollination would prevail.

Smilax flowers

If you’re going to sprawl all over somebody else, too lazy to build a trunk, why not be even more lazy and quit photosynthesis?   That’s true of several vines, most notably our “Love Vine.”    It is the orange spaghetti all over other plants.   Love Vine sends little suckers into the flesh of its host to help itself to the host’s hard-earned sugary sap.

Some species start out as epiphytes (or as vines) but as their size and needs grow,  send roots to the ground.   Best of both worlds, start out unrooted (or a little rooted) to get going in the sun, and then plant roots with maturity.    This is like getting a car loan…secure the car first (treetop sunshine), then use the car to go to a job and settle down to pay it off (plant roots).  Around here, Strangler Fig is the famous case.  Also guilty can be Rose-Apple and Muscadine Grape.

A more felonious approach is for an otherwise epiphytic species to sink its “roots” right into the host.  Approaching this, a lot of plants grow in the natural flower pots formed by moist debris-filled cabbage palm leaf bases.    Little or no known penetration of the Cabbage Palm’s living flesh.   But  Mistletoe (introduced a little) burrows right on into its host Oak tree.    There’s evidence that it is not totally a taker though.    Instead, it seems to “give back” sugar from its own photosynthesis, although this needs more research.

Golden Polypody Fern (top to the right), Cecropia (left with four big fingery leaves), Strangler Fig (far right), and Virginia Creeper (bottom) on Cabbage Palm

Most epiphytes develop their own special tricks for sitting up high and soil-less.    Their main problem is securing water and dissolved nutrients.  Many sidestep dry times by going into suspended animation when thirsty examples including mosses, lichens, liverworts, and resurrection fern.   These conduct business when wet.

Others capture and store rain water, stem wash, and mist.    Orchids have a covering, the velamen, on the roots.   Some have built-in rain barrels, most famously the “tank plant” bromeliads making a vase of their leaf bases.  A couple of these supplement their diet by adding carnivory to the tank, including one Florida native.

Most of our local Bromeliads, however, are tankless:  species of Tillandsia, including Spanish-Moss, Ball-Moss,” and many more, have a vesture of beautiful umbrella-shaped scales.  Water droplets catch under the scales, and suck into the plant through the central “trunk” of the scale.  Some Tillandsia Bromeliads and additional epiphytes offer living quarters for symbiotic ants in swollen puffy plant bases, or various hollow chambers.  The ants bring and create soil and manure, and certainly also provide guard duties.

Bromeliad scale under microscope

Who wants to see the pepper dance?  Non sequitor by PBSC student Ben Battat.