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Florida-Rosemary

06 Feb

Ceratiola ericoides

Ericaceae

 

The local white sand scrub was at its best today, sunny yet cool, with fresh growth and flowers, including white Innocence (Houstonia procumbens) and Sky Blue Lupine (Lupinus diffusus).    Although not near its peak, also with flowers was Florida-rosemary, a curious shrub.

Is it related to culinary rosemary? No

Does it smell like kitchen rosemary, no not at all, contrary to assertions all over the Internet.   (Here we have a great example of how BS can spread on the Internet.)

So why is the Florida species called rosemary?  A superficial resemblance, convergent evolution.

Ceratiola ericoides 5 far

Florida-rosemary.  All photos today (except halo) by John Bradford.

To my eye, Florida rosemary looks more like a conifer than a Mediterranean herb.  Its leaves are stiff, thick little “needles” arranged stiffly on vertical branches.  The little succulent leaves are an adaptation for life in the highest driest most exposed white (or occasionally yellow) sand scrub soils.   Deserts evolve succulents and needle-leaved plants, so hereya go.

ceratiola druits

Leaves and fruits (not today)

If you survive on high, super-drained, nutrient-poor sugar sand, is it better to have deep penetrating vertical roots to drill down to wetter layers, or to have widespread shallow horizontal roots?    Depends, I guess.   Saw palmetto has such deep roots they have “air pipes” built in.    Rosemary goes the opposite direction, its roots splayed out horizontally like an octopus on ice.   A little erosion exposes them.

ceratiola roots

Lotsa shallow roots

 

Having a moat of your own shallow roots has advantages.  Obviously you catch every drop of water and maybe even nutrient-bringing dust, debris, and rainwash as it arrives.    And there’s more:

Florida rosemary is one of the more famous allelopathic plants known to botany.  Allelopathy is the ability to poison the competition directly, or indirectly by interfering with microbes or nutrient availability.  Those roots undermining potential competitors undoubtedly help spread the chemical warfare.

Ceratiola chemistry is complex, and no doubt there’s still much to discover.   One of the more intriguing tricks up its sleeve is production of a compound called ceratiolin.   In the presence of light (stay tuned on that) ceratiolin transforms into a natural herbicide called hydrocinnamic acid.  Researchers have shown rosemary extracts to prevent germination or early growth of its frenemies, and rosemary in scrub enjoys splendid isolation, with a vegetation-free “halo” around the base.

Ceratiola halo

Keep out!   The rosemary on the right has a vegetation-free zone around the base.

Recently, biologist Cody Gale and colalborators related the nocturnal habits of the Rosemary Grasshopper (Schistocera ceratiola) to ceratiolin.   It seems if the grasshopper is out by day, the ceratiolin it ingests would turn by light exposure to hydrocinnamic acid, giving the buggie a tummyache.   I have a weird small-world personal connection to this insect.  One of the co-discoverers of the hopper in 1928, Theodore Hubbell, was a personal friend of my grandfather’s, who lived in Florida.   As Hubbell said, “Finding a new bug in the Florida scrub … gives me as much thrill as a hunter gets from bagging a deer.”

The grasshopper lives its life exclusively on Florida-rosemary, when young camouflaged as a rosemary leaf, and when older, camouflaged as the stem.  Check it out, by clicking here.

The grasshopper is not the only exclusive insect.  Also restricted to Florida rosemary is its own Leafhopper (Alconeura bisagittata), and a deeper curiosity, a small bug (Hemipteran) known as Keltonia balli.  It lives its simple life on the male flowers, eating the pollen. (The plants are separate male and female with the flowers small and non-showy.)

ceratiola male

The male flowers, how it looked today

Walking the scrub on a hot day presents a pleasant aroma, which I’m pretty sure comes from the rosemary.  Chemists have not ignored it.  The part that gets me wondering is why the aromatic volatilizations differ substantially seasonally.   If generalized reports of wind pollination with no pollinators to attract are accurate, could the seasonal emissions have to do with repelling pests?    Or, to stretch uncomfortably, with inter-plant signaling? That phenomenon is known.

I’d be scratching my head trying to think of another local plant with three insects all its own.

 
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Posted by on February 6, 2016 in Florida-Rosemary, Uncategorized

 

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Heterotheca’s Heterocarpy

20 Jun

Heterotheca subaxillaris

Golden-Aster, Camphor Weed

Asteraceae

This blazing 90 degree morning John and George* investigated red widow spiders, pine tree tip dieback, loblolly bay in fancy bloom, and mosses in Seabranch State Park near Stuart, Florida.  We botanize there often.

Feral hogs have stirred up patches of soil, with a consequence I always find interesting: pokeweed babies rising from the disturbed earth.   Pokeweeds are known for their heterocarpy, that is, differential circumstances for distribution and germination within a single species.   Many plants make mixed offspring in terms of how far the seeds or fruits will travel, or with seeds having mixed germination requirements and timing.  Reportedly in pokeweed some seeds are prone to sprout soon after release. Other sleep in the earth for decades until some hog stirs things up, even in a deep shaded woods unfit for pokeweed residence.  Some time ago in this blog we covered sea rocket, where half the fruit remains on the mother plant while the other half breaks free to go colonize new beaches.

Heterotheca subaxillaris (by John Bradford)

Heterotheca subaxillaris (by John Bradford)

The heterocarpic flower in pretty bloom this week is named for its hetercarpy: Heterotheca means “different containers,” in reference to its two types of fruits. Sometimes called Golden-Asters, Heterotheca subaxillaris is a common local bright sunny yellow-flowered weed on bright sunny dry sands. This species has extreme tolerance for drought and heat. Heterothecas (grandiflora) are so tough they have become invasive pests on Mars-like volcanic lava fields in Hawaii.

The leaves are fuzzy and smelly, giving today’s plant the name camphor-weed. I like the fragrance, but how many people know what camphor smells like, or even what it is? I just Googled camphor so I arrogantly know much about it for the next hour or two. Fact is, Heterotheca is a one-plant chemistry lab with a wide array of pharmaceuticals.  The “family” of fragrances Heterotheca brings to mind are wormwood, marigolds, and sunflower leaves.  (They are all related, and the similarity may come from lactone sesquiterpenes, but who cares?)

heterotheca jb

The obvious function of the stinky, sticky, chemical-laden, glandular hairy covering is to deter herbivory. Nothing would want to crawl upon or eat  camphor-weeds!   And there may be a secondary advantage to the hairs—protection from sun and drying.  Look at the death valley habitat in the photo above.   Plant hairs insulate the leaf surfaces from drying wind, and they block sun, maybe even reflecting solar radiation.   I don’t know if this is true of Heterotheca, but some botanists have suggested that glandular hairs might make a “sunscreen” that can spread and protect the foliar surfaces.  Even better, in other fuzzy species of similar habitats the hairs produce water-retentive compounds to create a moisturizing gel when the rains come.   It would be fun to look into some of this in Heterotheca which is so hairy and so oddly happy in a solar oven. The structure of the hairs helps define the genus.  A mutant hairless Heterotheca would probably wither unprotected.

As for the heterocarpy, in a flower head, most of the “seeds” (achenes) have parachutes to blow away to colonize a distant disturbed sand pit.   Some of the seeds, however, have no parachute, and recolonize their home neighborhood.

Heterotheca achenes showing heterocarpy: one has a parachute; one is bare. One flies far away; one keeps the home fires burning.

Heterotheca achenes showing heterocarpy: one has a parachute; one is bare. One flies far away; one keeps the home fires burning.

*Sorta let the blog slide.  Lost my mojo when our awesome international blog friend Mary Hart passed away in the U.K.  But John and George have kept up the botany—John has been working on the Seabranch site linked above, with some help from George.  And George has been developing a companion site to an introductory botany course, with a lot of John’s photos.

 
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Posted by on June 20, 2015 in Uncategorized

 

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The birds and the bees pollinate the trees, and now a sneaky peek at secrets in the creek.

25 Oct

Eelgrass (not a true grass)

Vallisneria americana

Hydrocharitaceae

Today’s blog represents a typographical techno-experiment. For the semi-blind like me, typing, proofreading, and correcting are always challenges. This week I’m trying voice recognition software and dictating into the computer. Let’s see how it goes.  Bear with me!

Vallisneria in the creek. By John Bradford.

Vallisneria in the creek. See the cylindric female flowers on their curly stalks.  By John Bradford.

This afternoon John and George visited a sparkling stream gurgling through the dry sandy pine woods at Seabranch State Park.  The contrast between the clear brook and the desertlike scrubland is striking, an oasis in the Sahara.  But of course, in place of date palms we saw sweetbay magnolias, pond apples, and red maples.  The muddy shores are as lush as the Amazon itself, housing oversized arrow arums, spadderdocs, arrowhead plants 7 or 8 feet tall, and even-taller grasses.

Today’s special botanical treat was hiding below the ripples wafting gently to its own music.  CLICK  Not wishing to sink up to our armpits in creeky goo, we fashioned caveman plant retrieval hooks from dead palm petioles and snagged a couple of the submerged plants.  We hauled ashore Eelgrass, also known as Vallisneria americana, a relative of the more familiar sea grasses of coastal pollution fame.

Vallisneria has its own pollution creds in a surprising way.  Research in the Detroit Area shows some strains of Vallisneria to be highly resistant to water pollution.  You might expect water plants generally to be diminished or extirpated by pollution, end of story.  But, surprise, it seems that decades or centuries of exposure to water-borne toxins have caused evolved tolerance.  Evolution in a historical timeframe is always interesting.   And here is a thought: if pollution kills the competition and Eelgrass has “learned” to cope with it, you might say pollution is good for Eelgrass…or just call it another human-induced tilt in the balance of nature.  And I was thinking today’s creek looks so pristine, well maybe not, eh?

Female flowers by John Bradford

Female flowers by John Bradford

Eelgrass lives beneath the surface of the water, yet still it requires pollination.  How?  Many aquatic plants raise their flowers above the surface like a periscope on a submarine.  But Eelgrass doesn’t; it uses the water itself.

A male plant. This is the structure that releases the male flowers to float to the surface. Photo by David Cameron (permitted noncommercial use).

A male plant. This is the structure that releases the male flowers to float to the surface. Photo by David Cameron (permitted noncommercial use).

Rooted in the submerged mud, the plant produces floating female flowers on a twisty thread resembling a coiled spring.  The tops of the female flowers and their pollen- receptive stigmas sit at the water surface in a tiny dimple.  Produced on separate plants, male flowers are the size of a pinhead and float unattached from the base of the plant to rise to the water surface like tiny lifeboats.  These little bobber boys have no physical connection to their mother plant.  CLICK HERE to see floating male flower highly magnified.  They’re top-heavy carrying the pollen on stubby elevated stamens.  You might say they resemble minuscule sailboats with top-heavy masts.  And like sailboats, they drift in the breeze and currents. When they come upon the dimple with the female stigma waiting within, the male flowers slide into the slippery slope and tip to dab their pollen load onto the receptive surface of the female flower.  Then its curly stalk pulls the now-expectant female flower protectively into the briny deep for the fruits to mature unmolested.

Vallisneria

We can’t end without a quick quack to the ducks.  Some dine on today’s species. In fact, the scientific name of the redhead duck is Aythya valisneria.  The Vallisneria plants form at their bases hardened buds to help the Eelgrass spread and as a retreat for tough times.  Botanists call these little tubers turions, but duckies just call them lunch.

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Here’s a link to illustrate the pollination event:  CLICK HERE

 
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Posted by on October 25, 2014 in Eelgrass, Vallisneria

 

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