A Neotropical Savanna

Note: This plant was identified faster than I would have believed possible by Nuytsia (blog, Flickr photos), based on his examination of the images I posted at Flickr. Thanks, Nuytsia!

I found this plant growing in the understory of a planted pine forest. I don’t know whether it strictly fits in the “neotropical savanna” category, but I found it so curious that I wanted to identify it. The red parts reminded me of the wax lips we used to be able to buy as children.

Recently, a visiting botanist reminded me of the value of learning plant families well. If you can get at the family, then you have a much better chance of learning the genus and species. This is a viewpoint I learned in my very first botany book, Botany in a Day, by Thomas Elpel, but I had drifted away from that approach, mostly because I was finding a habitat-organized book quite useful. If it didn’t serve me, though, I was basically stumbling around with each new plant, trying to find pictures in books or images on the web to steer me in the right direction.

So, this time, I’m taking the family point of view to work through the features of this plant. Psychotria poeppigiana, commonly known as “Hot Lips,” is a member of Rubiaceae, the coffee family.

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This tree blooms in the dry season in Panama – mature trees along the Interamericana highway near David are spectacular. This one is a young thing and even so the flowers are high up and I could zoom no closer.

Locally called Poroporo.

This banana flower first appeared on Thanksgiving Day (US) in 2006

A week later, several bananas had already developed.

In two week’s time, the bananas were pointing skyward, and I was sure we’d be eating bananas by Christmas.

In the third week, we began supporting the tree with a board. Later, because the wind kept blowing the board down, we wrapped a rope around the tree and tied it to another tree in the woods.

Then the plant seemed to go into a trance for a month and little external change was seen, except the flower kept unfurling bracts and dropping them to the ground, so the stalk grew longer.

Finally, on Lincoln’s Birthday, 81 days after the flower appeared, a touch of yellow appeared in the bananas.

The procedure here is to harvest the bananas while they’re green and hang them in a shaded area to ripen. Then you cut down the plant because it will produce no more fruit and its young are already growing. So the deed was done – one blow of the machete for the stalk –

and one blow of the machete for the plant.

(More details at Flckr.)

Now to wait for the ripening!

During the 1997-98 El Niño, the Panama Canal watershed experienced the worst recorded drought in the Canal history. There was a 25% reduction in runoff toward the tributary lakes of the Canal and a 58% decrease of water flow toward Gatun Lake. Draft restrictions were imposed on the ships passing through the Canal, and the number of ships passing through decreased by 4% during the second trimester of 1998 compared to the previous year.

My question: Why does Panama experience a drought during an El Niño whereas some other parts of the world experience excessive rain and floods? In this graph from the National Oceanic and Atmospheric Administration (NOAA) of the United States,

we see that the weather in Panama and some of Central America, northern parts of South America, and most of the Caribbean experience dry and warm conditions during June, July, and August, which for Panama are the early months of the rainy season. Wet regions are in the Pacific Northwest of the US and the west cost of southern South America. During December, January, and February, the beginning of the dry season in Panama, conditions in Panama may not be significantly different from normal.

To understand what causes the particular conditions in Panama, we must first understand in general what El Niño is and then see how El Niño affects the normal weather patterns.

I will not try to explain El Niño in detail since there are so many good descriptions already available on the internet, including at Wikipedia, NOAA, University of Illinois, and other sites.

For my purposes, I need only remember that Trade Winds weaken during an El Niño and the normally cold water off the west coast of South America is replaced by warm water.

To compare what happens during an El Niño versus what happens during a normal year in Panama, the key is going to lie in what happens to the Doldrums, or the Intertropical Convergence Zone (ITCZ). Remember from the last post that when the Doldrums are close to Panama, it rains. When they move south, it’s dry.

Thinking along these lines, I predicted that the El Niño warm water off South America would influence the position of the Doldrums, drawing them south, as it were. If this happened in the rainy season, then once the Doldrums were moved further away from Panama, rains would diminish. If it happened in the dry season, there would be little effect on Panama. These predictions would explain the pattern shown in the above illustration, but I had to search the web for quite awhile before I asked google the right question and found the data I wanted.

It turns out that when NOAA wrote up an analysis of that 1997-98 El Niño mentioned at the beginning of this post, one of their findings was that there was a strengthening and equatorward shift of the intertropical convergence zone (ITCZ) in the Northern Hemisphere during June, July, and August. Prediction supported!

Once again, the Doldrums explains much – our normal weather and our El Niño weather. It all depends on location.

As far as why some other parts of the world experience floods and rains when we’re experiencing drought – well, I’m going to wimp out on that. My general rule of thumb is that during an El Niño, weather is opposite what you normally expect. For instance, the Pacific Northwest of the US normally has dry weather during the summer (June-July-August) but will have rain then during an El Niño year. The “why” will depend on regional conditions and I don’t know enough about those conditions to say why it happens in that region.

This year’s (2006-2007) El Niño is weakening and will not have anything like the impact of the El Niño of 1997-98, which was particularly strong. Since El Niño events may happen roughly every 3 to 8 years, we’ll be seeing another in the not too distant future. It will be interesting to see whether we can predict its impact on Panama just by watching where the Doldrums are.