New study on carnivorous plants makes headline writers batty

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Before we get started, let me say that I forgive those who write headlines like pollution makes carnivorous plants go vegetarian and carnivorous plants go vegetarian in response to pollution and new study finds that pollution turns carnivorous plants into vegetarians. They know not what they do. It's also tempting to go after the flashy, attention-grabbing headline. Just try to do a better job next time, ok? And while we're on the topic, let us thank those that presented reasonable titles, like the one by Liat Clark at Wired.co.uk: carnivorous plants capture less prey in polluted bogs. Thank you for getting it a bit better! It would also be a terrible oversight if I neglected to mention that the Southern Fried Scientist took this issue to task a few days ago. Bravo!

So, on to the science at hand. What's all the fuss about?

Drosera rotundifolia at Triangle Lake Bog, Ohio. Photo by kitkor.

Drosera rotundifolia, the round-leaved sundew. Or common sundew. Or "bloody hell that thing is everywhere." And it is: North America, Europe, Asia... Here in Ohio it is the most common species of Drosera that you'll bump into - the other being Drosera intermedia, but several sites it had been known from have now been developed. For those unfamiliar with carnivorous plants, you might be peripherally aware that it is thought that these species have evolved in nutrient-poor environments. Given this idea and our knowledge that most species possess a good deal of phenotypic plasticity in response to environmental cues, researchers decided to further test earlier experimental observations that Drosera rotundifolia reduced its investment in carnivory (as measured by stickiness in units of force used to remove a piece of filter paper from the leaf) when grown in the presence of more nitrogen (Thorén et al., 2003).

Here in the new study, the researchers, a team including J. Millett of Loughborough University, B. M. Svensson and H. Rydin of Uppsala University, and J. Newton of the Scottish University Environmental Research Centre, were more interested in the relative amount of nitrogen that came from prey captured by normal means and from the roots as a result of increased nitrogen available from atmospheric deposition due to increased air pollution.

Briefly, the authors identified three bogs in Sweden that represented a gradient of mostly pristine to somewhat polluted in terms of nitrogen deposition. Fifteen specimens were removed from the bogs, dried, and analyzed for stable isotopes of nitrogen. Once they had their isotope data, all they did was subtract surrounding Sphagnum isotope data from Drosera and divide that by (insect - Sphagnum), where insect represents the mean isotope number for prey captured on the plant at the time of collection. And there's an easy ratio!

So conclusions from this? Well, the authors state it very clearly in the abstract, which many of the headline writers must have missed: "Drosera rotundifolia plants in this study switched from reliance on prey N to reliance on root-derived N as a result of increasing N availability from atmospheric N deposition." (emphasis mine) No, headline writers, these plants were not "OMG BECOMING VEGETARIANS!" Wouldn't that be a plant eating plant matter? And, as strange and wonderful as nature is, we have two possible examples in Nepenthes ampullaria and Utricularia purpurea where the former seems well-adapted to catch leaf litter and the latter appears to primarily cultivate algae in its bladder-like aquatic traps. No, dear headline writers, increased pollution will not turn Drosera rotundifolia into a vegetarian. It may, however, given this work and that before it, be the cause of changing priorities in nitrogen uptake from primarily prey-derived to primarily root-derived. It should be noted, however, that the authors did not set out to assess prey capture rates in these areas, so any statement has to be carefully worded and specifically related to nitrogen assimilation from different sources. We don't know if the plants in areas with more nitrogen capture fewer arthropods. It's entirely possible that the plants that incorporate more nitrogen from their roots capture the same number of prey but preferentially assimilate the nitrogen from the roots.

More troubling, however, is that with increased nitrogen availability in these once off-limits landscapes, opportunistic species may find it easier to overcrowd the poor little perennial carnivorous herbs. (Of course, the increase in nitrogen in this study was not very large and probably would not be enough to allow non-bog-adapted species to thrive.) Most carnivorous plants are low to the ground and depend on high light conditions to thrive; if shaded too much, they may soon succumb to succession. Of course this is only a hypothesis and needs to be studied! I wonder what the headline writers will say then...

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References

Millett, J., Svensson, B., Newton, J., & Rydin, H. (2012). Reliance on prey-derived nitrogen by the carnivorous plant Drosera rotundifolia decreases with increasing nitrogen deposition New Phytologist, 195 (1), 182-188 DOI: 10.1111/j.1469-8137.2012.04139.x

Thoren, L., Tuomi, J., Kamarainen, T., & Laine, K. (2003). Resource availability affects investment in carnivory in Drosera rotundifolia New Phytologist, 159 (2), 507-511 DOI: 10.1046/j.1469-8137.2003.00816.x

A sundew makes a hasty retreat

I'm not yet ready to send out the heralds and call this a success on my first go at cultivating tuberous sundews, but I'm closer now than I was before. If you recall, I originally purchased a lovely specimen of Drosera peltata from California Carnivores in January 2012 and first posted about it in March. It started out as a cute little rosette of carnivorous leaves, then bolted to produce two lovely 6-inch tall stems bearing those irresistible peltate leaves. And then throughout the last few months it was happily going about the business of, well, what sundews do best: capturing prey to collect nutrients.

Most of the tuberous sundews are native to Australia where the winter is rainy and the summer is hot and dry as a bone. This lineage of sundews has evolved the handy adaptation of giving up trying to survive as a full-fledged leafy herb during that hot, dry, unforgiving summer. Instead, they retreat into the soil, packing up their nutrients into root structures called tubers, not unlike a potato in many ways though much smaller.

In just the last few weeks as we approach the hottest late May and early June weather in the Northern Hemisphere here in Ohio, this particular specimen I had was finally ready to make its scheduled retreat. The leaves and stem quickly browned from the tips in a matter of days, my cue to stop watering and let the soil go bone dry lest the tubers succumb to rot as they form. And then, a few weeks later, out of curiosity and because I knew the soil surface in the pot was much too hard for the new growth to break through next year, I dug through the soil to find the tiny tubers:

Those little cream-colored pearls are definitely not perlite! A closer look:

In the above photo, the two tubers toward the top were still attached to the root, the dark brown object leading from center to the bottom right. It was a bumper crop! After sifting through the remainder of the soil, I found ten tubers in all:

The next challenge will be keeping them in a nice, dark place until next fall when they begin to stir. I think the hardest part will be remembering that I have them stuffed away somewhere!

And also, thanks to my friends at Botanical Oddities, I now have tubers from Drosera auriculata. Thanks, guys! Here's hoping I have success with both as I imagine the difficulties of growing tuberous sundews arise when preparing the new soil mix - the sand can't be too sharp or the new growth will be torn up on its several inch ascent from below. It will, at least, be a fun challenge.

Drosera peltata bit off more than it could chew

I found this grisly scene out in the greenhouse when I got home today. It looks like my Drosera peltata got a little overzealous, trapping this fly (ID? I'm hopeless at identifying anything with legs) by the head. It's at the end of this tuberous sundew's growing season, so all of that energy derived from this meal will be going directly to the tuber that should be forming several centimeters below the soil.

Drosera - Reach out and touch someone grab someone by the head.

Go read: Asking permission

Evolutionary biologist Jeremy Yoder who blogs over at Denim and Tweed just posted what I consider to be one of the best narratives of a volunteer for a campaign to defeat one of these repugnant state constitutional amendments that would ban same-sex marriage, this one in Minnesota. He recounts some of his experiences and conversations with Minnesotans who, as he says, are capable of being "astonishingly, densely homophobic, even when they're being Minnesota nice." It's worth the full read.

Ohio may have it's own gay marriage battle brewing, but possibly not until next year. Ballot language was just approved last week so that the Freedom to Marry Coalition is allowed to begin circulating petitions, hopefully gathering the 385,253 valid signatures needed for the issue to be placed before the voters on the November 2013 ballot. Why use the ballot initiative when it seems like an uphill battle? Well, the only way to allow gay marriage would be to repeal the constitutional amendment passed in 2004.

In 2004 62% of Ohioans voted in favor of enshrining discrimination in our state's constitution by banning same-sex marriages and civil unions. It has often been cited as one of the most restrictive amendments in the nation. It reads:

Only a union between one man and one woman may be a marriage valid in or recognized by this state and its political subdivisions. This state and its political subdivisions shall not create or recognize a legal status for relationships of unmarried individuals that intends to approximate the design, qualities, significance or effect of marriage.

A 2006 analysis on the effects of marriage equality on children reported in the journal Pediatrics by James G. Pawelski et al. notes the following on the Ohio law:

As a result, judges around the state have dismissed or reduced charges in domestic violence cases, because Ohio's domestic violence law recognizes the relationship between an unmarried offender and victim as one “approximating the significance or effect of marriage,” thereby representing a direct conflict with the amendment's prohibition against such recognition, thus rendering it unenforceable. [Their reference was this Cincinnati Post article]

 It's clear that the language of the 2004 amendment, specificially "legal status ... that intends to approximate...", has caused the most problems. This can be interpreted widely to include any contract my partner and I create that would "approximate" the qualities normally attributed to marriage. What exactly does this mean? It could be a will, or a private contract, or a medical directive like a power of attorney. And some judges have clearly taken it to mean unmarried partners in domestic violence cases do not require the same protections as married ones.

Unknown to the authors of the cited study above, Municipal Judge Paul Spurgeon of Mount Vernon, my adopted hometown since 2007, went so far as to deny several temporary protection orders in domestic violence cases, often a very necessary and important step regardless of the sexual orientation of those involved, based on his belief that granting temporary protection under the "person living as a spouse" condition would mean recognition of same-sex marriage. Motion denied. (I'm honestly surprised there wasn't more outrage over this.)

I guess the point is that this law is doing real harm and causing a fair amount of chaos in some court proceedings related to domestic violence. But... the effort to repeal the ban and replace it with one that allows marriage faces its own chaos. Apparently, not all organizations are on board and the focus is split, with critics suggesting we should put our energy into obtaining housing and employment nondiscrimination rights first. ("No state has passed gay marriage that has not first had protections in housing and employment," or so I heard on NPR this morning.) And then there's the local perspective. Rick Santorum won my county's Republican primary, but I do have hope that the pendulum is slowly swinging the other direction. This local news story from Marietta, a small town on the Ohio River in Southeast Ohio not known for being liberal got the opinion of four locals. The only dissenting voice was, naturally, from the Catholic priest. The others, ages 19 to 42, said they support the measure and that it didn't matter to them if gay people can get married or not. I'm not sure if the petition efforts will amount to anything and then if the general public will actually vote for the measure in 2013, but, inspired by others, I might put in my own volunteer time.

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Pawelski, J. (2006). The Effects of Marriage, Civil Union, and Domestic Partnership Laws on the Health and Well-being of Children PEDIATRICS, 118 (1), 349-364 DOI: 10.1542/peds.2006-1279

The shield sundew

Encouraged by a Facebook post from California Carnivores and on a whim I decided to get my first tuberous sundew a few months ago. These are plants with a decidedly curious habit unfamiliar to those of us where winter normally equals dormancy. During the winter, more accurately described as the wet season, the plant will spring up out of the soil and produce first a flat rosette of leaves and then begin to bolt, sometimes attaining a height of 50 cm. Once the high heat normally associated with the Australian dry season arrives, the plant withers and retreats to a tuber some 4 to 6 cm underground. I suppose this unfamiliar habit is the reason why tuberous sundews get the reputation of being quite difficult to maintain - they must be kept wet but not soaked in the winter and nearly bone dry in the summer. Luckily, California Carnivores occasionally stocks Drosera peltata, the shield sundew, so named for the shield-shaped leaves, reportedly one of the easiest tuberous sundews to grow. A beginner's plant, if you will.

So far, I'm thrilled with it! I just hope that I'm able to keep the tuber viable through the summer.

As a bonus, I also received the above dainty flowering plant, Utricularia bisquamata. Known as a prolific weed of the carnivorous plant world, I'm not sure if I should torch it or try to contain it. If I don't do something, it is nearly guaranteed that it will end up taking over every single pot in my collection.

Berry Go Round #49

Oops. Looks like I've been neglecting the link-back duty. At the end of February, Bora Zivkovic over at A Blog Around The Clock posted the results of all submissions from February botany-related posts. Among the gems this month were not one but two (Elizabeth Preston and Ed Yong, respectively) discussions of the news that scientists were successful in resurrecting a living plant from seed tissue hidden away by squirrels 30,000 years ago. And then there's the provocatively-titled Are Sheep Better at Botany than the US Government? by Jason G. Goldman of The Thoughtful Animal. And you must not miss the wonderful post by Colin Beale, The paradox of the prickly: Why grow thorns if they don't work? at one of my favorite group blogs, Nothing in Biology Makes Sense! And for the chemically-minded, there's a great post by Andrea Wills titled, Why "Natural" isn't always better: almond extract and cyanide.

Well, you get the point. Go check them all out! And if you have any plant-related posts, consider submitting them or nominating someone else's for the March compilation, which will be hosted by Greg Laden over at ScienceBlogs.

The orchid that smells like Chanel No 5

Dipodium roseum, a parasitic Australian relative. Photo by Ian Sutton.

The orchid genus Dipodium, collectively known as the hyacinth orchids, includes somewhere between 20 to 30 species native to Southeast Asia and Australia. Interestingly, the majority of the species are leafy epiphytes - well, terrestrials that climb and then become epiphytes - dispersed throughout Southeast Asia. A small group of these plants, however, have lost the leaves entirely and live as terrestrial parasites at the base of Eucalyptus trees in Australia.

This, of course, is interesting on its own, but what caught my attention today was the description of a new species in 2006 by Peter O'Byrne and Jaap Vermeulen. They found Dipodium fragrans growing in eastern Johor state of Peninsular Malaysia, inhabiting the lowland swamp-forests common to the area. Dipodium fragrans, as you can deduce from the species epithet, is heavily perfumed, so much so that it led to this humorous description, hidden away among the often stuffy and sometimes inaccessible language of academic botany:

D. fragrans is noteworthy in two other respects: the inflorescence is often branched, and the flowers are strongly fragrant, hence the specific name. Vermeulen describes the scent as "being like Chanel No 5", while O'Byrne (a poor schoolteacher) is ignorant about luxury fragrances and likens the scent to frangipani's.

Science, including the scientific descriptions of  new species, could learn a lesson from O'Byrne and Vermeulen. A little humor, properly placed, makes for a more engaging read. It certainly stuck with me more than if that comment had been omitted!

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Reference:

O'Byrne, Peter, and Jaap Vermeulen (2006). Two Cheirostylis species and a new Dipodium. Malayan Orchid Review, 40, 91-94

Fairy aprons

This plant was given to me by Douglas Darnowski identified as Utricularia paulineae, a beautiful species of bladderwort from southwest Western Australia described by Allen Lowrie in 1998 and named in honor of his wife. However, now that it has flowered, I believe this to be a specimen of the variable Australasian species Utricularia dichotoma (the lower corolla lip is not nearly reniform enough to be U. paulineae), commonly called fairy aprons. Isn't that precious? The small size of these flowers - no larger than your pinky fingernail - and the ruffles certainly fit the common name perfectly. And those colors! Brilliant violet with a neon yellow landing guide.

Carnival of Evolution #44

The newest edition of the Carnival of Evolution, this month's writings on evolution from the busy denizens of science blogosphere, is up at The Atavism. As always, I'm impressed by the work of Carl Zimmer, this time on ion pumps in fungi. Also interesting are the posts "How the cricket lost its song" and another on how extinction isn't always, well, extinction. Even my earlier post on triggerplant morphology was chosen. Got some free time and feel like a little bit of science today? Go check out all the links!

Berry Go Round #48

This month's Berry Go Round, the botanical blog carnival, is up at Jessica Budke's Moss Plants and More. As a survey of this month's botanical blogging, it's got everything you'd ever want: the curious history of an accidental botanist and his impact on our knowledge of the flora of Wyoming, a discussion on the new USDA plant hardiness maps (aside: I note that I'm still stuck in the anomalous Zone 5b bubble in central Ohio surrounded by Zone 6a), and an amazing blog dedicated to illustrating a botanical word a day. My post from earlier this month about the carnivorous habits of Philcoxia was also featured.

Thanks to Jessica for putting this month's Berry Go Round together. Take some time to check out each of the links presented this month.