American Persimmon

I will never forget the time I went to the grocery store and bought what I thought were strange tomato varieties. I got home and dug into them only to discover they were not tomatoes at all. I quickly realized the error in my judgment. Instead of the unmistakable flavor of a tomato, what I experienced was something slightly sweet and kind of astringent. I had inadvertently purchased a couple persimmon fruits. I was young and naive so I will cut myself some slack, however, like any good mistake, I was rewarded by the inadvertent introduction to a fascinating fruit I had never experienced before. 

Thinking this to be some strange tropical species, I was surprised to learn that North America does indeed have its own species of persimmon. Known scientifically as Diospyros virginiana, the American persimmon is native to much of the eastern U.S. but is absent north of Pennsylvania. We are lucky, biogeographically speaking, to have this species as the family to which it belongs, Ebenaceae, is predominantly tropical. It is an early successional tree species, often growing on recently abandoned farmland. In the spring this shrubby tree produces small yet attractive white and yellow flowers. American persimmon are dioecious meaning individual trees are either male or female. Their main pollinators are bees.  

As is often seen with many fruiting tree species,  there is a lot of variety between the fruits of different persimmons. They can range in size from small crabapples to the tomato-like fruits we find in the grocery store. There are those who suspect the fruits of the American persimmon to be a throwback to a time when animals like woolly mammoths and ground sloths roamed this continent, dispersing persimmon seeds as they roamed across the terrain. Indeed, fossils of American persimmon have been found in Miocene deposits in areas of Greenland and Alaska which suggests that this species has undergone range contraction, potentially due to the loss of these large seed dispersers. However, modern day evidence would seem to suggest otherwise. Today, much smaller animals like raccoons and opossum seem to do just as good of a job as a larger animal would. It is likely that the constricted range of the American persimmon has more to do with climate than seed dispersal. 

If you have never tried a persimmon before then seek one out and give it a go. If you find them in a grocery store, there is a good chance the fruit belongs to the Asian species (Diospyros kaki). The key to enjoying an American persimmon is making sure its ripe. If you are too early you are going experience some of the worst tannin dry mouth (I honestly don't think I will ever convince my mother to eat another strange fruit again). Either way, this neat species often goes overlooked until it is in fruit. Keep your eye out for fruiting persimmon in your area and report back if you decide to sample some. 

Photo Credit: Doug McAbee (http://bit.ly/1xznvPx)

Further Reading:
http://www.na.fs.fed.us/pubs/silvics_manual/volume_2/diospyros/virginiana.htm

Why We See Color

Seeing the world in trichromatic color is a wonderful thing. I truly feel for those who can't. Humans, by and large, have pretty decent color vision. We have three different kinds of opsins on our cones which allows us to see the variety in hues that we do. It is a trait we share with apes and most Old World monkeys. Why do we possess such a wonderful adaptation? As it turns out, plants were likely the driving factor.

Whereas most mammals tend to have only two different kinds of opsins (dichromacy), the primate lineage from which we evolved developed trichromacy at some point in the past. Why did this happen? The answer may lie in the diet of our common ancestors. As climates changed over time, the common ancestors of Old World monkeys, apes and humans had to constantly adapt to new food sources. A majority of primate diets consist of fruits and leaves. Being able to distinguish between ripe and unripe fruit would be a valuable advantage to have. For our ancestors, dichromacy would have made this quite difficult. Thus the evolution of trichromacy would have incurred quite a selective advantage to our ancestors.

The advantage doesn't end with ripe vs. unripe either. Trichromacy would have also made finding colorful fruits against a backdrop of green much easier as well. Even for the majority of primates that eat leaves, color vision would have been quite useful. Leaves can vary in edibility and even toxicity with age. Being able to tell younger from older leaves could easily make the difference between life and death for these primates. Leaf color is often the only way this can be done. Again, selection for color vision would have quickly spread through these populations. So, the next time you stop to admire a flower or any of the wonderful colors of the world around you, take a moment to think about the fact that plants just might be the reason you can enjoy that wonderful sense.

Photo Credit: Jay Neitz Laboratory (http://www.neitzvision.com/content/people.html)

Further Reading:
http://anthro.palomar.edu/primate/color.htm

http://rspb.royalsocietypublishing.org/content/263/1370/593

http://www.sciencedirect.com/science/article/pii/S0047248402001677

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.