Monthly Archives: November 2013

Cattails Are Very Edible; Phragmites Want to Poison Them

Visiting family in Delaware, I rediscovered an old book called A Field Guide to Edible Wild Plants by Lee Peterson.  Figuring a post on an edible plant would be appropriate for Thanksgiving, I cracked the book and was captivated by this note on Typha latifolia, also known as the common cattail:

Probably no other plant, wild or domestic, is more versatile than Common Cattail.  In addition to yielding food year-round, it provides the material for making torches, mattresses, rush seats, and flower arrangements.

That’s the text accompanying the plate image of the plant.  The full text is full of more lush detail on just how one might eat cattails year-round.  The edible portions of cattails include “young shoots and stalks, immature flower spikes, pollen, sprouts, [and] rootstock.”  I think my favorite detail is this:

In earliest spring as they begin to extend, but before they break through the surface of the mud, these sprouts can be peeled, boiled briefly, and pickled in hot vinegar.  In addition, the starchy core at the base of each sprout can be prepared like a potato.

Who knew?

I thought I’d remembered that cattails were in danger of replacement by invasive Phragmites here on the east coast of the United States.  Phrases from the Wikipedia “cattail” entry like “dominant competitors” and “aggressive,” as well as tips for destroying cattails through burning and flooding made me doubt myself.

Other sources, though, bear out the narrative of Phragmites displacing cattails.  So this led to new questions — most centrally, if cattails are so “dominant” and “aggressive,” then how are they being displaced by Phragmites?

It turns out the likely answer to this question emerges from Delaware too: researchers at the University of Delaware discovered a few years ago that upon exposure to UV irradiation, a root-secreted toxin from Phragmites facilitates rhizotoxicity in susceptible plant species.”  In other words, sunlight leads Phragmites to release poison from their roots that kills competitors.  This result led the researchers to “hypothesize that the photo-chemically transformed products of GA in aquatic ecosystems could be potentially toxic to competing grass species leading to marsh invasion and monoculture formation by Phragmites.”

I’ll be honest: it’s Thanksgiving, so I’m not going to put the time into figuring out the mechanism for this competitor-poisoning behavior by Phragmites right now.  It does sound really interesting, though, so look for it here later.  For now, let’s just take a moment to thank members of the genus Typha for being so useful — and apparently delicious — and to stand in awe of the complexity of plant life that surrounds us every day.

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Diplodocus for Sale — Sold

Remember that Diplodocus that was for sale?  It sold today for £400,000.

According to the BBC, “An undisclosed institution bought the skeleton, which auction officials said would be going on public display.”  Whether that’s display in a carefully curated science museum remains to be seen — the BBC quotes the auctioneer as saying, “Within the context of a shopping mall you can make a real ‘wow’ statement.”

Wow is right.

A Thousand-year-old, Exoskeleton-building Arctic Alga

The exoskeleton of a thousand-year-old Arctic alga has allowed scientists to reconstruct historical data on Arctic temperatures and sea-ice cover.  Not surprisingly, according to the  abstract of a new paper from University of Toronto professor Jochen Halfar, “algae show that … the 20th century exhibited the lowest sea-ice cover in the past 646 years.”

Perhaps more suprising than the recent drastic loss of Arctic sea ice is the fact that there exists a thousand-year-old, exoskeleton-building, Arctic-dwelling alga in the first place.  It’s called Clathromorphum compactum.  And it’s pink.  Let’s take a closer look and see how C. compactum has allowed scientists to study ancient sea ice.

A master’s thesis from a former student of Prof. Halfar’s [pdf] provides some details about Clathromorphum compactum and its exoskeleton-building ability:

C. compactum has been found in marine habitats of the Northern Hemisphere, including the North Atlantic, North Pacific, and the Arctic oceans. This long-lived crustose coralline alga builds its skeleton by depositing annual layers of high-magnesium calcite.

Morphologically C. compactum displays cell differentiation with small and heavily calcified cells formed during the cold months, separated by large and poorly calcified cells built during the warm periods. This abrupt change is marked by a growth line.

In other words, take a cross-section of one of these skeletons and you’ll see rings just like the ones that provide evidence of a tree’s age and health record.

The same master’s thesis explains a little bit about how C. compactum and its relatives build their skeletons:

Crustose coralline algae build their calcified skeletons by precipitating calcite crystals directly in the vegetative cell-wall.  While the external factors influencing crustose coralline algae calcification such as temperature, salinity, pH, light, and food availability have been investigated, the physiological processes are less understood.

The effects of temperature and light on algal skeleton-building are particularly significant to anyone who wants to extract information from the skeletons’ growth lines.

As to temperature, the warmer the weather, the more magnesium the algae’s skeletons contain.  This means that the amount of magnesium in a particular ring of a skeleton’s cross-section can show us how warm or cold the water was when the skeleton was built.

And as to light, sea ice blocks light and inhibits the alga from growing at all.

The takeaway is this: when there’s warm water and not much sea ice, C. compactum builds thick, magnesium rich layers of exoskeleton.  And according to Prof. Halfar’s abstract, that’s what’s been happening for the last hundred-plus years:

The 646-y multisite record from the Canadian Arctic indicates that during the Little Ice Age, sea ice was extensive but highly variable on subdecadal time scales and coincided with an expansion of ice-dependent Thule/Labrador Inuit sea mammal hunters in the region. The past 150 y instead have been characterized by sea ice exhibiting multidecadal variability with a long-term decline distinctly steeper than at any time since the 14th century.

So please take a moment to thank C. compactum and its peculiarities for serving science and confirming that we’re busily destroying our planet.

P.S. Apparently, while the alga Heterosigma akashiwo is not a plant, the alga Clathromorphum compactum is a plant — a plant that builds exoskeletons.  Weird.

A 20th Century Extinction: Thismia americana, fungus-feeding plant

I made a bet with myself that I could find an interesting North American plant species that went extinct in the last 100 years.  It took only about 5 minutes to win the bet.

In 1913, botanist Norma Pfeiffer earned her PhD from the University of Chicago at age 24. 

There’s so much impressive material in that last sentence that I’d recommend you read it again. 

Ok, now we can continue.  Dr. Pfeiffer would go on to become an expert on lilies (so says the New York Times), but it’s her PhD work that’s relevant here.  As part of her thesis, Dr. Pfeiffer discovered the species Thismia americana right in Chicago.

Why was — and is — T. americana noteworthy?  We’ll let Dr. Pfeiffer explain first in her 1914 paper “Morphology of Thismia americana“:

The entire plant is glabrous and white, save in the 6 divisions of the perianth, where free, and in the disk closing the perianth mouth.  Here there is a delicate blue-green color, deeper in the raised ring about the aperture of the disk. …

In the older part of a root of Thismia, there is evident a very conspicuous epidermis. … The layer of cells immediately below the epidermis is packed with the thick-walled, branching mycelium of a coarse fungus. …

Since the fungi occur in the root, the absorptive region, and not in the stem, they would seem to have some connection with water and food supply.

Hm.  A 2004 story in the publication Chicago Wilderness uses lay language:

Thismia americana was a mystery right from its discovery. Instead of drawing energy from the sun, Thismia fed on fungi that grew in its roots, spending much of the year underground. In midsummer, a tiny tube-like flower pushed upward an inch or so, and only the upper quarter actually emerged from the soil. Its three petals remained linked at the top of the tube, leaving arch-like entries for small insects to pollinate. Lacking chlorophyll, the entire plant was smooth and translucent white, with hints of pale blue-green stripes that deepened at the tip of the flower. By September, the blossoms seeded and withered, and the plant disappeared underground for another year.

Or, if you prefer, here’s the Chicago Tribune in 1991:

What makes the plant so unusual is that by all rights it should never have grown here. Its nearest relative is a tropical plant that is found in New Zealand, Australia and Tasmania. It contains no chlorophyll, the substance that allows other plants to make their own food and gives them their green color. Instead, thismia lives on soil nutrients that a fungus in its roots digests for it.

A plant that mostly lived underground, lacked chlorophyll, and instead of producing its own food ate only courtesy of root fungi?  Pretty neat.

Thismia Americana “was seen for five consecutive years, and it has never been found again despite repeated searches by scientists and botanical groups” [pdf]; accordingly, it is now generally believed to be extinct.

A Sabertoothed, Bear-sized, “Mammal-like Reptile”

Last night I finished the massive-open-online-course “Dino101: Dinosaur Paleobiology” from the University of Alberta, hosted by coursera.  I learned that, in my dino-myopia, I’ve been overlooking a host of interesting animals that existed in the Permian age.  The Permian age, by the way, directly preceded the Mesozoic Era (the age of dinosaurs) and came to an end when the single greatest mass extinction in Earth’s history occurred.

The Dino101 course lecture briefly noted the existence of gorgonopsians, a family of carnivorous, sabertoothed “mammal-like reptiles” that ranged in size from housecat to bear.

Inostrancevia alexandri in all its glory, courtesy of Wikipedia user Ghedoghedo.

On further review, it appears that the most imposing gorgonopsian was the genus Inostrancevia, which could reach approximately 3.5 meters long.  Inostrancevia was also possessed of “exceptionally large canines,” according to the impressively thorough doctoral thesis of Eva Gebauer.

As this is the first I’ve learned of the gorgonopsians, I don’t have much else to add for today.  If anyone can round out my extremely basic description of the gorgonopsians, and Inostrancevia in particular, with some color commentary, I’d love to hear it.

In any event, these were some fearsome beasts and the creatures they ate seem to have been interesting too.  But that’s a topic for another day.  In the meantime, let’s just settle for knowing that the sabertoothed, bear-sized Inostrancevia existed — until the entirety of Gorgonopsia was completely wiped out by the end-Permian mass extinction.  Inostrancevia exists today in only two forms: its fossilized remains, and a 5-inch-long replica you can buy if you’re so inclined.

One final note on the Permian for today’s purposes: apparently, a “protosphagnum” existed then.  One wonders whether gorgonopsians burned it to dry the barley they used to make gorgonopsian whisky.

Glowing scorpions

Speaking of blue bioluminescence, did you know that scorpions and some other arthropods glow blue under ultraviolet light?  A fascinating post from Wired explains the mechanism and some reasons scientists have hypothesized for why these creatures glow as they do.  Below is an interesting excerpt from the post, but you’ll really want to click through to read the read the rest — and see the pictures.

For scorpions, the mechanism of the glow has been studied in more detail. Scorpions have “cuticular fluorescence.” Basically, compounds in their exoskeleton absorb and re-emit ultraviolet light as visible light (light humans can see). The exoskeleton of an arthropod is made from composite materials that are both strong and flexible. It’s the outermost layer, epicuticle, that produces the glow, and it seems to be something that changes chemically as the animals grow.

Two compounds are involved in scorpion UV fluorescence: beta-carboline and 4-methyl, 7-hydroxycoumarin. You might recognize coumarin as a common plant compound, and it’s often used as a perfume or in cinnamon flavors.

Blue Bioluminescence in the Parchment Tube Worm

In other underwater-color-related news, scientists can’t figure out how the parchment tube worm, Chaeteopterus variopedatus, manages to glow blue while most other bioluminescent sea life glows green.  They’re getting closer, though:

Light production usually occurs when two chemicals react together with oxygen to produce a compound that then produces light, [Scripps Institution of Oceanography biologist Dimitri] Deheyn said. In past studies, researchers have found that glowing stops in the absence of oxygen.

But when Deheyn’s team removed oxygen from the tube worm, the worm continued glowing. …

In a separate experiment, the team found that riboflavin — also known as vitamin B2 — plays an important role in the worm’s light production, but its exact role remains unclear.

The blue glow comes from a mucus that the tube worm secretes into a housing tube it builds for itself.

You can read the abstract and part of the introduction to the first paper yourself here.  Not only the worm but also the paper itself actually quite colorful: the authors note that the worm “produces from various parts of its body a bright luminescent mucus that is generated in abundance and somewhat constantly on stimulation; the mucus can be produced in such abundance that when squeezed underwater during scuba diving, a cloud of light is noted puffing out of the tube into the water.”

Impressive!

Reference
D. Deheyn, L. Enzor, A. Dubowitz, J. Urbach, and D. Blair. (2013). Optical and Physicochemical Characterization of the Luminous Mucous Secreted by the Marine Worm Chaetopterus sp. Physiological and Biochemical Zoology, Vol. 86, pp. 702-705.