The Floating Bladderwort

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A carnivorous plant species that uses its radially arranged stolons like tiny pontoons to float at the waters surface may sound like something out of a science fiction novel. However, it is a very real strategy  adopted by one of the coolest carnivorous plants in North America. Utricularia inflata is one of the largest species of floating bladderwort on this continent and it is a species worth knowing.

Sometimes referred to as the swollen bladderwort, this species enjoys a native range that extends through much of the southeastern United States. For most of the year it exists in a state quite similar to other aquatic bladderworts. It has no true roots or leaves. Instead it produces a long, filiform stolon covered in tiny filaments that act as leaves with bladder traps situated at their tips. It sits in the water  column, gobbling up anything small and unfortunate enough to stumble into it.

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When flowering time approaches, these aquatic carnivores begin producing a different kind of stolon. Arranged like spokes on a wheel, the plant puts out swollen, air-filled stolons that float at the waters surface. These structures support the inflorescence. Flowers are bright yellow and resemble those of many other bladderwort species. Entire bodies of water can literally erupt in a sea of yellow bladderwort flowers when the right conditions present themselves.

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As mentioned, this species is carnivorous. It uses tiny bladder traps to suck in unsuspecting prey. Their diet is varied and includes pretty much anything that can fit into its bladder traps. One research paper reports both animal (rotifers, cladocerans, copepods, annelids, rhizopodeans, as well as small insects) and "plant" (Bacillariophyta, Chlorophyta, Cyanophyta, and Euglenophyta) prey.

Unfortunately these plants have been introduced far outside of their native range. In many areas they are becoming prevalent enough to be considered invasive. For instance, research done in the Adirondack Mountains of New York found that the presence of introduced populations of U. inflata caused significant changes in nutrient cycling, sediment chemistry, and overall net primary productivity.

This is a very neat species well worth a closer look. That being said, if you are a hobbyist such as myself, it is very important to remember that we should never release a species (no matter how cool it is) into areas where it isn't native.

Photo Credit: www.sarracenia.com, Dr. Mark Whitten, [3] [4]

Further Reading: [1] [2]

A Plant With Lobster-Pots

Pitfall, pitcher, urn, snap, bladder, sticky - all of these words have been used to describe the various means by which carnivorous plants capture their prey. But what about "lobster pot?" Believe it or not, there is a genus of plants that has evolved a strategy for catching prey that would make lobster fishers proud.

That genus is Genlisea. It comprises roughly 30 species of what are common called "corkscrew plants." They are native to both Central and South America as well as Africa. These plants are small and can be found growing in saturated, nutrient-poor soils, conditions that select for any trait that can supplement what the plant can't get from its soil environment. Unlike more charismatic carnivorous plants, the meat-eating habit of this group would not be readily discernible to the casual observer.

Above ground they resemble their cousins the bladderworts (Utricularia). The flowers are quite showy and most species present them in either yellow or purple. At ground level sits a dense rosette of leaves. These are only part of the foliar picture. The corkscrew plants produce an entirely different set of leaves that take care of their nutrient needs. To find these, however, one must look underground.

Genlisea have no roots. Instead, they are anchored into the soil by truly bizarre, highly modified leaves. These leaves produce no chlorophyll and look absolutely nothing like what we expect leaves to look like. Instead, they form a hollow cylinder that corkscrews down into the permanently saturated soils in which it lives. This is where its carnivorous habits take place.

Along the length of each corkscrewed leaf runs a slit-like opening. Lining the mouth and inside of the chamber are backwards pointing hairs. Like a lobster pot trap, animals can enter these slits with ease. Getting back out, however, is nearly impossible. The only option trapped critters have is to continue onward to their doom. Towards the end of the traps sits a chamber where most of the digestion takes place. A quick caveat here: to say animals is a bit misleading. Most of what these plants are feeding on are small, soil-dwelling protozoans.

Regardless, the traps are quite efficient. It was only recently discovered that this was a true form of carnivory. Darwin himself had suggested it after careful examination but it wasn't until the 1990's that any digestive enzymes were detected. Still, it is a bit of a mystery exactly how or even if these plants actually attract their prey. Some researchers have found substances within the cylinders that are hypothesized to act as chemical attractants, however, more work needs to be done on this.

The traps don't spell certain death for all life. In an interesting study, researchers identified 29 different kinds of algae living inside the traps. Since dissolved oxygen is quite low inside, most of these algae are specialized for anoxic environments. The nature of the relationship between the algae and the corkscrew plants is not certain at this point. Some think it might be commensal whereas others feel that the algae may compete with the plant for phosphorus. Again, more work is needed.

The carnivorous nature of this genus isn't the only interesting aspect of their evolutionary history either. Some member of this genus, specifically Genlisea aurea, exhibit some of the smallest genomes of any flowering plant. This is not an ancestral state for this group meaning that at one time, the common ancestor had a much larger genomes but subsequent pruning has gotten rid of most of the "non-coding" sequences. Though there is plenty of speculation as to why this has happened, it is still anyone's guess at this point.

Photo Credits: NoahElhardt (assumed-Wikimedia Commons), Scott Zona (http://bit.ly/1ZHACAk), and B Mlry (http://bit.ly/1ZHAEbw)

Further Reading:
http://www.tandfonline.com/doi/pdf/10.1080/12538078.2005.10515466

http://aob.oxfordjournals.org/content/114/8/1651

http://aob.oxfordjournals.org/content/100/4/849.short

http://aob.oxfordjournals.org/content/100/2/195.short

http://bmcgenomics.biomedcentral.com/articles/10.1186/1471-2164-14-476

bit.ly/1WurdqE

Bladderwort Bliss

The bladderworts (genus Utricularia) are already pretty awesome when you consider their carnivorous habits. However, to lay eyes on the bewildering variety of shapes, sizes, and colors of their blooms brings about a whole new appreciation for these marvels of evolution.

Photo Credits: Boaz Ng (http://bit.ly/1DfHJiO), Tim Waters (http://bit.ly/1JSxaee), David-Emil Wickström (http://bit.ly/1E1E8Kn), Steve Garvie (http://bit.ly/1zMla44), eyeweed (http://bit.ly/1DfI19p), B Mlry (http://bit.ly/1wmRj0x), satish nikam (http://bit.ly/1FAHgtI), Kevin Thiele (http://bit.ly/1Flouqd)

A New Look at a Common Bladderwort

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It is so often that common species are overshadowed by something more exotic. Indeed, we know more about some of the rarest plants on earth than we do about species growing in our own back yards. Every once in a while researchers break this pattern and sometimes this yields some amazing results. Nowhere has this been better illustrated in recent years than on the humped bladderwort, Utricularia gibba. 

This wonderful little carnivore can be found growing in shallow waters all over the world. Like all Utricularia, it uses tiny little bladders to capture its even tinier prey. Despite its diminutive size, U. gibba is nonetheless a very derived species. For all of its wonderful physical attributes, the real adventure begins at the microscopic level. As it turns out, U. gibba has some amazing genetic attributes that are shining light on some incredible evolutionary mechanisms. 

When researchers from the University at Buffalo, Universitat de Barcelona in Spain, and LANGEBIO in Mexico decided to sequence the genome of this plant, what they found was quite startling. For a rather complex little plant, the genome of U. gibba is incredibly small. What the researchers found is that U. gibba appears to be very efficient with its DNA. Let's back up for a moment and consider this fact. 

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The genomes of most multicellular organisms contain both coding and non-coding DNA. For decades researchers have gone back and forth on how important non-coding DNA is. They do not code for any protein sequences but they may play a role in things like transcription and translation. For a long time this non-coding DNA has been referred to as junk DNA. 

This is where things get interesting. Sequencing of the U. gibba genome revealed that only 3% of its genome consisted of non-coding or junk DNA. For some reason the U. gibba lineage has managed to delete most of it. To put things in perspective, the human genome is comprised of roughly 98% non-coding or junk DNA. Despite its rather small and efficient genome, U. gibba nonetheless has more genes than plants with larger genomes. This may seem confusing but think of it this way, whereas U. gibba has a smaller overall genetic code, it is comprised of more genes that code for things like digestive enzymes (needed for digesting prey) and cell walls (needed to keep water out) than plants with more overall genetic code such as grapes or Arabidopsis. 

As one author put it, this tiny ubiquitous plant has revealed "a jewel box full of evolutionary treasures." It is a species many of us have encountered time and again at the local fishing hole or in your favorite swimming pond. Time and again we pass by the obvious. We overlook those organisms that are most familiar to us. We do so at the cost of so much knowledge. It would seem that the proverbial "Old Dog" has plenty of tricks to teach us. 

Photo Credit: Kevin Thiele (http://bit.ly/1Flouqd) and Reinaldo Aguilar (http://bit.ly/1B6mnHN)

Further Reading:

http://www.nature.com/nature/journal/v498/n7452/full/nature12132.html

http://mbe.oxfordjournals.org/content/early/2015/01/31/molbev.msv020

http://plants.usda.gov/core/profile?symbol=UTGI