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Chromolaena  odorata

Asteraceae

Across vast areas around the warm-climate world, including Florida, lives Jack in the Bush, a huge, raggedy, hairy, smelly,  weak-stemmed weed up to 10 feet tall, often leaning on other plants.   The leaves often look bedraggled, and they suffer often from leaf miners.

The flower heads start out white and wind up borderline pretty and pinkish, fuzzy, with long protruding stigmas.   They attract several species of butterflies as well as additional insects.  Notice I did not say insect “pollinators,” because the bug visits are pointless to the flower…there is almost no pollen.

Jack in the Bush, white phase. Both photos today by John Bradford.

Members of the Aster Family generally share a common basic pollination plan.   The flowers have 5 male pollen-making anthers joined edge-to-edge into a tube with pollen released into the hollow inside of the tube.  The female style then rises up through that tube and either pushes pollen out like a plunger ahead of its  two pollen-receptive stigmas, or the style drags pollen out of the tube using a “bottle brush” below the stigmas.  Jack belong to the bottlebrush type.    Its long style rises dramatically from the anther tube exposing two big long stigmas just asking to be pollinated.  Below the stigmas on the style is the bottle-brush where there ought to be pollen.   Only problem is, there’s almost none.  What’s up with that?

Mature flowers. The long threads are stigmas on the styles.

Knowing a plant to be a worldwide weed is a red flag to look for some ability to reproduce rampantly without benefit of separate individuals of the same species.   That is, for a pioneer to be able to make seeds all alone. There are many such mechanisms, and one is to make eggs that do not require sperm, or in more botanical terms, viable seeds bypassing pollination.

True of today’s species.  Jack in the Bush has six sets of chromosomes instead of the usual paired chromosomes we think of as normal.  Extra chromosome sets are not rare in plants, and have different consequences in different species.   Normal paired chromosomes matter during formation of eggs and sperms.    Our chromosomally abnormal weed cannot make pollen, at least not much of it.   So how does it spread like a weed?   No problem,  the extra chromosome sets do not prevent egg formation,  In fact, just the opposite, eggs form needing no pollination.  The embryos are clones of the mother plant.

Probably all the Jack in the Bush in Florida is probably one big genetic clone.  The butterflies love it nonetheless.

Rhizophora mangle

(Rhizophora means root bearing.  Mangle is Spanish for mangrove.)

Rhizophoraceae

Red Mangroves astound in many ways. One of the is the embryo.   The Red Mangrove embryo bobbing in the sea looks like a purposeful eel swimming vertically with its head above water.  Before getting far into the swimming, a few words on the embryo’s nuts and bolts.

A normal fruit on any other plant contains one or more seeds, and each seed in that normal plant houses a tiny embryo destined to grow into a new oak tree or orchid.    But Red Mangrove is not normal.   It makes a small rusty-leather fruit the size of a strawberry containing two seeds., one of them surviving.   So far so good, but now it gets weird.  The seed sprouts while the fruit still dangles from the parent tree.  The resulting embryo, resembling a large green bean, grows forth from and eventually dwarfs its fruit and may reach about a foot long and a half-inch in diameter dangling from the tree, the original fruit forming a brown cap around the green embryo’s attached upper end.

Embryos looking like green beans hanging on the parent tree.  The fruits are the brown caps at the upper ends of the embryos, which will soon drop free leaving the fruits behind on the tree.

When it finally comes time to go float to a new beach, the embryo breaks free, leaving its topmost parts (the cotyledons) behind within the fruit.   The part that falls into the sea then is an enormous root (hypocotyl) vertical below the water line with a little pointy tip exposed above the surface.  The pointy tip is the beginning of the top part of the future tree, the embryonic leaves, stems, and trunk.

Embryo floating in the Atlantic Ocean.

The pointy tippy top.

Why does the bottom end stay down while the top end stays up?    Not only is the bottom thicker, it also fails to have something the top possesses…open hollow airspaces.  The spaces clearly give the top end buoyancy, and perhaps have an additional role in gas storage and exchange.

Hollow spaces seen when the top part of the embryo is sliced open.

Here is the kicker.  The floating embryos cross oceans.   Their cruise can reportedly last a year.   For all those months the sojourners do not merely dormant and sleep their way across a thousand miles.  Rather, it looks like they live and breathe along the way.   Even when the root end down in the water turns brown, the upper end remains green and has chloroplasts.   There must be a reason the little swimmer keeps its head above water, no doubt the same reason I do…life support, gas exchange.   Those little submarines have circled the earth bobbing along with their  snorkel tops peeping above the waves.

Carolina Redroot, Lachnanthes caroliniana

(Lachnanthes means woolly flower.)

Haemodoraceae

Carolina Redroot is famous for its namesake red roots.   Been there, done that:  CLICK

This wetland bleeder hangs around where feral hogs snuffle the earth.   Correlation does not show cause, however.   Do the hogs seek out the redroot?  Do they spread it?   Or does the plant happen to grow in mudholes hogs fancy for other reasons? I don’t know. And for this moment, I don’t care, because what I wish to discuss are the unusual flowers, visited at least by bees, wasps, and butterflies.

The butterflies come for nectar, and perhaps the bees come mainly for pollen.  Somebody is going to have to sit a long time in a marsh with camera, binoculars, and bug net to tell the full story of Lachnanthes pollination.

What’s  weird about the flowers is that seen from the side the style with its pollen-receiving stigma is bent outside of the floral center, at about the same height as the pollen-releasing anthers.

Side view of woolly flowers. Anthers are dusty yellow. Stigma marked with blue line.

Flower from above. Three anthers yellow. Style green angled up and left.

Seen from above, the stigma juts out to the side about as far as the likewise bent anthers do.  Picture the flower as a clock face.  In the photo above the anthers are at 12, 5, and 7 o’clock releasing dusty yellow pollen.  The green style with pollen-catcher stigma at its tip is at 10 o’clock.      The stigma is in a spot where you’d reasonably expect an anther. Within an inflorescence, the bent stigmas point in every direction.

What’s up with that?  One answer, not original with me, is that the stigma is out of the way of all the sundry pollinators, but it seems there is more to it.  Given that the stigma occupies an “anther position,” an insect visitor is as likely to contact the stigma as any single anther.   Visitors approach the flowers oriented variably.   Spot on the insect pollen-dusted on a different flower will occasionally hit the stigma spot.  Twenty-five percent of the flower touches will be pollen drop-off, the other 75 percent will be pollen pick-up from the insect’s standpoint. This presumably accomplishes two things:

Accomplished thing 1. Accommodation of the diverse floral visitors.   All manner of bees, wasps, butterflies, and who knows what can play redroot-roulette, even perched on one flower  sipping nectar from another, or while feeding vertically as well as horizontally.

Accomplished thing 2. The roulette system may help promote cross-pollination. The incoming pollen is scattered on various insect body points from past visits to other flowers.  The different pollen-pickup points on the insect may carry pollen from multiple flowers.   The pollen deposited on a stigma is equally likely to have come from any of many flowers, all depending on where the roulette wheel stops.   A great system for mixing genes.

Redroot roulette.   The insect in the diagram picked up pollen on its right side and deposited that pollen on the next flower it visited.  Perhaps on its next stop it will drop off pollen from its left side, or from its chin.

Partial to redroot is the gray hairstreak butterfly. Today one was alternating between two plants, ignoring all others.  Most of its flower action is head down, for a reason.   The head is inconspicuous, while the fanny looks like a showy head, complete with orange coloration, false eyes, and best of all, fake antennae.

Head down on redroot. Fake antennae “up.”

An attacker is likely to go for the wrong end of the butterfly.  You might think a bird would gobble it up altogether, so what good is that fake head?  Entomologist Andrei Sourakov from the University of Florida found out.   The predators fooled are not big birds, but rather spiders.  They inject their venom into the wrong end of the butterfly.  Score one for the graystreak.

Sipping nectar

The rear end with false eyelashes.

BRIEF VIDEO  Watch the fake antennae wiggle: CLICK

THE END