The Intriguing Pollination of a Central American Anthurium

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As an avid gardener of both indoors and out, there are few better experiences than getting to see familiar plants growing in the wild for the first time. That experience is made all the better when you find out new and interesting facts about their ecology. On a recent trip to Costa Rica, I was introduced to a wide variety of Anthurium species. I marveled at how amazing these plants look in situ and was taken aback to learn that many produce flowers with intoxicating aromas.

I was also extremely fortunate to be in the presence of some aroid experts during this trip and their knowledge fueled my interest in getting up close and personal with what little time I had with these plants. They were able to ID the plants and introduce me to their biology. One species in particular has been the subject of interest in an ongoing pollination study that has proven to be unique.

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The plant in question is known scientifically as Anthurium acutifolium and it is rather charming once you get to know it. It is a terrestrial plant with relatively large leaves for its overall size. Its range includes portions of lowland Costa Rica and Panama. Its flowers are typical of what one would expect out of this family. They are fused into a type of inflorescence known as a spadix and can range in color from white to green and occasionally red. If you are lucky to visit the spadix between roughly 8:00 AM and 12:30 PM, you may notice a rich scent that, to me, is impossible to describe in words.

It's this scent that sets the stage for pollination in this species. During some down time, University of Vienna grad student Florian Etl discovered that the spadix of A. acutifolium was getting a lot of attention from a particular species of small bee. Closer inspection revealed that they were all males of a species of oil-collecting bee known as Paratetrapedia chocoensis. Now, the females of these oil collecting bees are well known in the pollination literature. They visit flowers that secrete special oils that the females then use to build nests and feed their young. This is why the attention from male bees was so intriguing.

A: A male  P. chocoensis  bee approaching a scented spadix of an inflorescence of  A. acutifolium . B: The abdominal mopping behavior of male  P. chocoensis  oil bees on a spadix. C: Ventral side of the abdomen of a male  P.chocoensis  covered with pollen. D: A male  P. chocoensis  bee on a spadix of an inflorescence of  A. acutifolium , touching the pollen shedding anthers. E: Pubescent region pressed on the surface of  A. acutifolium  during the mopping behavior. F: A scented inflorescence of  A. acutifolium  with three male  P. chocoensis  individuals. G: Image of the abdomen of a male  P.chocensis  in lateral view showing the conspicuous pubescent region. ( SOURCE )

A: A male P. chocoensis bee approaching a scented spadix of an inflorescence of A. acutifolium. B: The abdominal mopping behavior of male P. chocoensis oil bees on a spadix. C: Ventral side of the abdomen of a male P.chocoensis covered with pollen. D: A male P. chocoensis bee on a spadix of an inflorescence of A. acutifolium, touching the pollen shedding anthers. E: Pubescent region pressed on the surface of A. acutifolium during the mopping behavior. F: A scented inflorescence of A. acutifolium with three male P. chocoensis individuals. G: Image of the abdomen of a male P.chocensis in lateral view showing the conspicuous pubescent region. (SOURCE)

Males would land on the spadix and begin rubbing the bottom of their abdomen along its surface. In doing so, they inevitably picked up and deposited pollen. To date, such behavior was unknown among male oil bees. What exactly were these male bees up to?

As it turns out, the males were collecting fragrances. Close inspection of their morphology revealed that each male has a small patch of dense hairs underneath their abdomen. The males are definitely not after fatty oils or nectar as A. acutifolium does not secrete either of these substances. Instead, it would appear that the male oil bees are there to collect scent, which is mopped up by that dense patch of hairs. Even more remarkable is the fact that in order to properly collect these fragrance compounds, the bees are likely using solvents that they have collected from other flowering plant species around the forest.

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What they are doing with these scent compounds remains a mystery but some potential clues lie in another scent/pollination system. Male orchid bees perform similar scent-collecting activities in order to procure unique scent bouquets. Though the exact function of their scent collecting is not known either, we do know that these scents are used in the process of finding and procuring mates. It is likely that these male oil bees are using them in a similar way.

Taken together, these data suggest that a very specific pollination syndrome involving A. acutifolium and male oil bees has evolved in Central American forests. No other insects were observed visiting the flowers of A. acutifolium and the scents only ever attracted males of these specific oil bees during the hours in which the spadix was actively producing the compounds. This is a remarkable pollination syndrome and one that encourages us to start looking elsewhere in the forest. This, my friends, is why there is no substitute for simply taking the time to observe nature. We must take the time to get outside and poke around because we stand to miss out on so much of what makes our world tick and without such knowledge, we risk losing so much. 

Photo Credits: Florian Etl [1]

Further Reading: [1]

Is it a pine? Is it an apple? It's neither!

Pineapples - the fruit that is neither a pine nor an apple. In reality, pineapples are a type of bromeliad. The genus to which they belong, Ananas, is comprised of something like 7 different species, all of which are native to Central and South America. Considering we rarely encounter these plants outside of a grocery store, it is no wonder then that many are surprised to realize how pineapples grow.

The fruit itself is not the entire plant. It is made up of many fruits that fuse together after flowering. The flowers themselves are quite lovely and originate from the center of the hexagonal units that make up the tough rind. The whole inflorescence arises from the center of a large rosette of leaves. Only when you see the entire plant does the bromeliad affinity become apparent. Like all other bromeliads, pineapples undergo vegetative reproduction as well. Small offshoots called "pups" arise from the base of the plant and the axils of the leaves. These can take root and grow into clones of the parent plant.

In the wild, pineapples require pollination to set seed. This is undesirable in cultivation because pollination means lots of seeds that consumers don't want to contend with. Because of this, pineapples are gassed with ethylene, the simplest of plant hormones. Ethylene causes the fruits to artificially ripen without being pollinated. In this way, no ovules mature into seeds.

The dirty little secret about pineapple farming is that it is done at great environmental cost. The dominant producer of pineapples is Costa Rica. Because of the humid, tropical climate, insects and fungi flourish. In order to ensure that production is maximized, pineapple farmers dump thousands of gallons of pesticides and herbicides onto their crops. These farms are largely void of all other lifeforms save for endless hectares of pineapples. This, however, is not a story unique to pineapple farming. The same could be said for all other forms of monoculture farming.

Photo Credits: Fractalux, H. Zell, and hiyori13 - Wikimedia Commons

Further Reading:

http://www.kew.org/science-conservation/plants-fungi/ananas-comosus-pineapple

http://www.theguardian.com/business/2010/oct/02/truth-about-pineapple-production

What a Dichaea

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The orchid genus Dichaea includes some of the strangest orchids i have ever seen in person. Take this one for example. My sources tell me this is likely D. globosa. Right off the bat, the bristly seed pods are a tell for this genus. With this particular species, each stem juts off of the trunk of a tree at a near 90 degree angle. The stem itself is horizontally flattened and the subtle yet beautiful flowers emerge from between the leaves and are presented below the plant, facing the ground. I had seen this orchid out of flower in a few places in Costa Rica, however, I was lucky enough to stumble across these individuals in flower while hiking in Panama. An exciting find for this orchid fanatic!

Central America - Part 2: The Journey to San Vito

The sun was up and burning by 6 AM. We were sweating by the time we arrived at the bus station. I always over-pack. Always. My backpack was loaded with extra clothes and camera gear. Luckily we were in store for a 6 + hour bus ride. The night before didn't do much in the way of helping me catch up on sleep. Alajuela is a loud city. It seemed like none of the cars had mufflers. Every passing hour came complete with multiple car alarms as well. Despite our exhaustion, we were excited to be catching the bus to San Vito. 

We first had to catch a bus into San Jose. It was an interesting process. It was a weekday morning and we quickly got caught up in rush hour traffic. Walking was easy. It would seem that driving in this country takes a whole new set of skills that I simply do not have. There are no street signs and everyone seems to follow some unwritten Darwinian traffic code - only the strongest survive. Trucks and buses move in and out of tiny, crowded streets without hitting the cars sandwiched in between them. Motorcycles and mopeds weave their way through what little space remains. Watching this unfold was an experience unlike anything I had ever encountered. I would surely crumble under these conditions. My pampered American ways had no place on these roads. 

We managed to find the first bus. What should have been a 15 minute commute from Alajuela to San Jose was actually going to be about an hour. Luckily I found myself sitting next to a man names Carlos. His English was perfect, probably better and more formal than my own. Carlos could certainly sense how out of place I was and was kind enough to strike up a conversation. As it turns out, Carlos is a plant scientist working at an agricultural research institute in San Jose. His work centers around making Costa Rican farming more sustainable. His current project involved introducing new potato varieties from Peru into the mix to help transition away from monocultures. 

We talked for a while about his approach to this but his concerns seemed daunting. Like everywhere else in the world, Costa Rica is facing an uncertain future with climate change. Areas that once sustained certain types of farming are no longer able to do so. He made sure to point out every farm along our rout and explain to me what was obviously wrong - huge, chemical-laden coffee plantations, timber lots chock full of invasive eucalyptus trees, and almost no erosion control anywhere, which is clogging up tropical streams with an endless supply of runoff and sediments. 

I could have talked to Carlos all day, however, we had to part ways. I was lucky to have met him. We grabbed a cab to the next bus station. Yet another awkward ride ensued as the kind cab driver did his best to speak in slow, easy Spanish. Within an hour our bus had arrived. We boarded with only a handful of other people. From what I have come to understand, there are two main routs from San Jose to San Vito - one takes you through the mountains and the other takes you down the coast. With my face glued to the window, it soon became apparent that our driver was taking us through the mountains. 

Like a kid in a candy shop, the scenery had my complete attention. The combination of the size of the bus and the elevation that we had to climb meant that the ride was slow enough that I could actually do some botanizing from the window. Again, I had almost no idea what I was seeing. The only plants I was remotely able to recognize were some sort of Dicranopteris fern that covered exposed roadsides and plenty of bamboo orchids (Arundina graminifolia), a species that has naturalized throughout the tropics but was originally native to parts of Asia. The rest quickly became a green blur of tree ferns, palms, and other tropical looking trees. I couldn't wait to explore with someone who knows a thing or two about Costa Rican flora.

We actually made good time considering the length of the trip. In just under 6 hours we were walking down the main path at the Wilson Botanical Garden. Here we were to meet our friend Dave. We found him watering some cacti. Though this was technically the rainy season, they had not received any rain in over a week. Some of the plants didn't quite know what to do. We found our sleeping arrangements for the next few days and were anxious to start exploring. The main grounds of the garden were jaw droppingly gorgeous. There was more plant diversity within a stones throw than anywhere else I have ever been. Dave had some work to finish up so he gave us a map of the grounds and sent us on our way. 

Being completely new to this area, I was a bit wary of what I might encounter. Does Costa Rica have its own tropical version of poison ivy? Was I going to brush up against or touch something that would result in a rash? I asked Dave if there was anything I should avoid and he had only one response, caterpillars. "Don't touch any of the caterpillars. Some can totally ruin your day." Noted. 

Being much closer to the equator than New York, we had to get used to the sun schedule. It starts getting dark around 6 during this time of year and we didn't want to be out unsupervised after dark. We kept our musings to the immediate area near our cabin. A friend joked that going to a botanical garden in a rainforest is kind of like going to a zoo in Africa. Though it was a funny comparison, it couldn't be farther from the truth. The beauty of the Wilson Botanical Garden is that it allows you an up-close and personal look at the flora. Sure, there are paths and labels but these are a great place to familiarize yourself with some of the local species before setting off blindly into the jungle. Begonias and gesneriads carpet walls and rocks, Palms offer shade for ferns and orchids alike. Countless endemic bird, insects, and amphibians haunt these grounds. We even saw our first wild agouti. I was both overjoyed and overwhelmed. 

As if on cue, it happened. We rounded a bend and dangling off the side of a tree was an orchid in full bloom. It was Gongora armeniaca. I never really understood what it meant to be speechless until this moment. In fact, I don't think my brain could fully comprehend what it was seeing. The long inflorescence was in full bloom. Each of its strange flowers were perfect. I have seen Gongoras before as curiosities tucked in the back of orchids rooms at various botanical gardens. However, nothing comes close to seeing a species like this in situ. I was going to have to pay a lot of attention to trunks and branches if I was going to see more botanical wonders like this. 

Central America - Part 1: Costa Rica

This journey really began back in April. Grad school was coming to a close and our move to Illinois was scheduled for August. A celebration was in order. Other than a brief exploration of a Caribbean island and a few visits to Florida, I have never really experienced anything remotely tropical. Through documentaries and an obsession with houseplants that borders on hoarding, I developed a longing for the equatorial rainforests of the world. It was high time I visited some. 

We managed to find ourselves some cheap tickets into Costa Rica. My friend and horticultural mentor, Dave Janas, had taken a job at the Wilson Botanical Garden in San Vito. I could not think of a better person to introduce us to the flora and fauna of this region. With our flights set we now had something to day dream about for the next few months. 

In no time at all the day had arrived. We hopped on a plane in Buffalo, NY and in less than half a day we had landed in San Jose, Costa Rica. All we had were our backpacks and some cash. No matter how much you read and prepare there is always going to be some culture shock. This was especially true in my case. I had been to Portugal as a kid, though I hardly remember most of it. Other than Canada and the Caribbean, I have not traveled much outside of the country. I was ready for something new and challenging but very little sleep and my almost non-existent grasp on Spanish made the first few hours a bit trying. After an awkward cab ride from the airport in San Jose to our hostel in Alajuela, I needed to regroup a bit. 

After a small nap, I was ready to get my bearings. It was time to explore Alajuela a bit. We decided to grab some food and see what the parks were like in town. Getting around town proved to be a slow process - not because of transportation or any sort of infrastructure but because every garden was teaming with plants I have either never seen before or only encountered in the indoor section of a nursery or botanical garden. Poinsettias and palms were obvious favorites. They decorated most open lots. There were also a handful of mango trees dotting the city scape. When we finally arrived at the park, I could barely contain myself. 

It wasn't very big but it was packed. The ground was trampled as well. It was obvious that this was quite a popular place. Most of what was growing there were various palms and each palm was adorned with its fair share of tillandsias. It didn't take long for my ever-present search image to locate a few orchids as well. At this point you may be asking "what species?!" and to that I will say that I haven't the slightest idea. I was quickly realizing just how out of my element I was. Other than some of the more obvious plants that decorate houses and offices up north, most of what I was seeing was completely new to me. This was going to be an exciting trip. Never in my life have I been this ignorant to the plants and animals around me. If this is how the dense urban centers were going to be, I could hardly wait to run off into a real rainforest. That leg of the adventure was to begin at dawn the next day. 

We found a fruit vendor and grabbed some dinner for the evening. It consisted of some granadilla (Passiflora ligularis) and rambutans (Nephelium lappaceum). We sat on a bench and ate all the while a pair of crimson-fronted parakeets were loudly tending to something inside a hole in a dead palm. I had finally done it. I was finally about to explore one of these tropical wonderlands.