A Neotropical Savanna

It still surprises me that there are so many members of the composite family (Asteraceae) in the tropics. It should not be surprising – the aster family and the orchid family are the two largest families of flowering plants. But somehow I feel the orchids belong in the tropics and the asters belong in the temperate world.

Even wikipedia says that although the aster or composite family is cosmopolitan, it is more common in the temperate climate and in tropical mountains. Nevertheless, the tropics are loaded with members of the aster family. Here in the western hemisphere, in the neotropics, we have 580 genera and 8,040 species of composites. By contrast, we have 300 genera of orchids and 15,000 species. (Statistics from Maas.) So, we have more species of orchids, but we have more genera of composites. Not as clear-cut as I previously thought.

Here in the savanna, in the dry season, the composites are conspicuous. We even have trees in the family Asteraceae – four of them are listed in the Trees Atlas of Panama.

One of those trees is the palo blanco – a brittle tree that suffered quite a bit of damage during the recent high wind episode.

Its scientific name is now Vernonanthura patens, although in its botanical history it has had at least six other names, one of which was Vernonia patens. The only complete description I’ve found for palo blanco is one in the Flora of Panama (Part IX. Family Compositeae), when it went under the name Vernonia patens. So I’ll be going through that description to show how to recognize the palo blanco, or Vernonanthura patens.

Vernonanthura patens is a Shrub or Small Tree to 8 m Tall

This young tree is no more than about 2 m tall, but I have seen them much taller, some on our own property, and one along the road to David that surely exceeded 8 meters – it seemed nearly 50 feet (15 m) tall.

The tree is “freely branched.” See how open and free the branches are in this young palo blanco. The branches themselves are marked with fine, usually parallel lines or grooves. You can see more freedom of branching in the image on the left, below, and the fine lines show up pretty well in the image on the right, especially when you click to enlarge it.

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The winds earlier this month caused more damage than a downed Miconia tree, and the damage was more extensive than I realized until I compared the most severely injured area with an earlier photograph. Here are the before (November 2008) and after (February 2009) shots. (Click on image to enlarge.)

The wind damage is compounded by the contrast between the conditions at the end of the rainy season and conditions two months into the dry season. Before I go into that, I should explain the sticks leaning against the banana plants. These are crutches put there to support the plant once a bunch of bananas develops. If the plant is not supported, the bananas will pull the plant down. The bag is placed over the ripening bananas in an attempt to keep the birds away (Black-chested Jays are especially noisy and destructive).

Okay, here’s the damage report. (Click on image to enlarge.)

In the upper left corner is a leaf-less tree (deciduous in the dry season) that I have not yet identified. A large limb split off it and fell onto an already fallen Miconia and onto one of the banana plants. The Miconia has been mostly cleared away, but it also damaged banana plants and for awhile provided a highway for squirrels to get to the ripening bananas under the bag. The Miconia also pretty much demolished the fern stand. As noted, banana leaves normally take on a shredded appearance in the dry (and normally windy) season. They are designed to do that without causing damage to their vascular systems.

And here’s the comparison between the seasons.

At the end of the rainy season the grass is green; in February it is brown. The banana leaves are fairly intact in the rainy season and are shredded in the dry season.

The bijao (the large-leafed plant at the extreme right of both images, Calathea lutea) is bright green in the rainy season, and not all of the leaves are erect. In the dry season, the leaves are grayish, shredded like the bananas, and nearly all are completely erect to expose themselves to less sun than if they were more parallel to the ground (this movement of the leaves is a characteristic of this groups of plants and for this reason they are known as “prayer” plants).

Between the bijao and the bananas is an Eugenia biflora, which has just finished blooming and so looks a little paler than it normally would because it is studded with pale green developing berries.

All in all, with the wind damage and the normal drying impact, the pleasant little area looks pretty devastated. However, it’s a miniature ecological event as well. At the edge of our tiny forest, a new “gap” has been created. It will be interesting to watch as it responds to this new situation.

In celebration of the 200th birthdays of both Charles Darwin and Abraham Lincoln, the sandpaper plant burst forth in bloom again today, this time attracting a new beetle.

The image is not as well focused as I would like, but the beetle appeared and then disappeared, never to be seen again. So this is what I got.

The other beetles, the weevils that I saw last year and also two weeks ago, returned, as did the bees. This time all insects were in much greater number – probably a thousand bees at this one plant by 7:30 in the morning. I had a harder time estimating the beetles, but there were easily twice the number that there were two weeks ago.

I do not expect this plant to produce more profuse blooms this season. Now is the time to gather all my notes and try to make sense of what went on.

In a much more humble celebration today, I launched another blog, The Accidental Botanist, where I can ramble on about plant things that are unrelated to our neotropical savanna.

When a tree along the roadside comes into bloom, it always catches my eye, and I always think, “I have to come back and look at this more closely, and take pictures.” I don’t take my “photo-journalism” trips nearly as often as I’d like, but a couple of weeks ago I was able to study a tree that’s almost in our back yard – within a good hike of our house, anyway. I don’t know how many times I have passed this tree by without really seeing it, and then, there it was in bloom.

As soon as I saw those big stand-up flowers, I thought, “bat-pollinated.” It’s something a botanist friend taught me some time ago, and I’ve looked for it ever since. Bats are flying around at night, using radar, and they need a big, conspicuous object, lifted above the leaves, to zoom in on. A common, but non-native, bat-pollinated tree here in Panama is the African Tulip Tree, Spathodea campanulata. If you click on the following image to enlarge it, you’ll see why I could tell, even at a distance, that this tree is bat-pollinated, with those white vanilla ice cream cone flowers at the top.

This tree is the famed Balsa tree, the wood of which was used for the Kon Tiki, for airplane models and even for light wooden real airplanes. The word “balsa” is, according to wikipedia, Spanish for “raft.”

The scientific name for this tree is Ochroma pyramidale and it is in the Malvaceae family. Here’s why.

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