A Neotropical Savanna

Sunrise (6:49 AM): After watching this plant, the sandpaper plant, Davilla kunthii, for an entire month, I was beginning to wonder whether it would ever bloom. But on the evening of January 29, I saw quite a bit of yellow peeking out of the buds and the next morning at sunrise (6:49 on January 30 here in Potrerillos) when I arrived at the plant, the buds were ready to burst into bloom. A few bees were already hovering around the plant.

As the morning progressed and the flowers opened, it became clear there were two kinds of bees interested in this plant – a large one (circled), and a small bee. (or is it?), below. (The image below, as noted by a correspondent – with an Asian name I can’t translate – is a type of hover fly. I have some other images of the small bee, but they’re not clear enough to post.)

8:00 AM: At least a couple dozen bees were buzzing around. By 8:30 there may have been 50 or more. It was clear that the large bee, at least, was collecting pollen. My only image of this so far is fuzzy, but it’s not hard to see the orange pollen sacs.

8:30 AM: the first few weevils. The weevils are the entire reason I was sitting in the shade comfortably, with my coffee and notebook, watching this sandpaper plant put on its spectacular bloom. I had seen and photographed a weevil swarm last year, and Robin Foster of The Field Museum of Chicago suggested I look at the swarm more closely this year. I’m going to be tracking this plant throughout its blooming period to watch for these weevils.

That they are weevils has been verified by Dr. Henry Stockman who is this January at the Smithsonian Tropical Research Institute here in Panama and kindly looked at my images from last year. He suggested that it is possible that these weevils are eating the pollen – which is a rich protein source. As I watched, I could not see whether they were eating, but they certainly did not seem to be collecting it the way the bees were.
By the time the weevils arrived, some of the petals had already dropped from the flowers. The flowers had gone from opening bud at just before 7 AM to fully open flower, to the commencement of petal-dropping at 8:30 AM. One and a half hours. Astonishing!

9:30 AM: The number of bees was down and the number of weevils was up.

10:30 AM: The petals were seriously dropping off. I could hear the petals landing on the sandpaper-like leaves. They sounded like raindrops. There were even fewer bees, but the weevils were still there.

11:15 AM: Nearly all the petals were gone but several weevils stuck around. When the petals fall off, the cup-like green sepals, which underlie the petals, are left behind with the stamens. The weevils seem unperturbed by the absence of petals and simply crawl around the sepals looking for their pollen meal.

1:30 PM: The sepals were closing in on the stamens. A few weevils were still around, hoping to avoid getting trapped in the sepal jaws, I assume.

4:00 PM: The sepals are completely closed around the stamens. I saw one forlorn weevil crawling around on the sepal surfaces. Some sepals qwew separated enough to show yellow – they’re the ones that were bursting with petals to open the next day.

What a day for a plant! I’m sure Darwin would have loved the show. Remember his study of the “sleeping” leaves of the little machete plant, Erythrina? I wonder what he would have made of the opening and closing jaws of these sepals.

Several of the living fence post species are in bloom now. Living fence posts are fence posts that have sprouted after becoming a part of a fence. They can be obvious posts with a few sprouts coming out the top, or they can have grown into full size trees while still serving as fence posts.

The yellow-flowered macano was a living fence tree described last year, and the “little machete” or machetito that we’re looking at today and that is shown below is in the same family – the Fabaceae or bean family.

The Flowers
Surely you can tell from the flower where the common name came from – the red petal looks like the blade of a machete and the calyx (the cup of sepals at the base of the petals) looks like the machete handle.

While looking at the flower, we can ask ourselves to which of the three large groups within the immense Fabaceae family this plant belongs. You may recall that the three groups, or subfamilies, are based on flowers that look like 1) peas, 2) mimosa (flowers like soft spiny balls), or 3) Caesalpinia-like flowers, which are brightly colored and showy flowers such as found in Flamboyant trees.

So which is this? Since the flowers are definitely not soft spiny balls, we are left with peas and with the showy flowers of the Caesalpinioideae subfamily. If you go to Wayne’s World, you’ll find a discussion of this group of trees, which are called in English “coral trees.” He has dissected one of these flowers here to show how this machete blade is really part of a pea flower, with all the remaining parts being reduced.

Let’s defer further thoughts on the flower for now – we will shortly look at them more closely to see just why just the one part of the pea flower should be conspicuous.

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Quick! What is this flower? An orchid, a lily, or an iris?

You may have been able to answer immediately because you are very familiar with all three kinds of flowers, but is was it about this one that told you what it is? If you didn’t know what it was, don’t worry, the answer will be given later.

Orchids, lilies, and irises each belong to a different family: Orchidaceae (22,000 species), Liliaceae (1600 species), and Iridaceae (1500 species), respectively. Each family is widely distributed throughout the world. (Click on any image to enlarge.)

The flowers are so showy and beautiful that they’ve been thoroughly cultivated, and if you’re at all familiar with flowers, you can probably easily distinguish any of the three cultivated flowers. But what if you happen upon one in the wild?

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This vine belongs to the plant family Malpighiaceae, which is the family of the nance, a favorite fruit tree here in Panama. Because the family is represented only in the tropics and subtropics, I want to spend a little time comparing the parts of the nance plant with this vine, thereby looking closely at some of the family’s characteristics.

First, though, about that awkward family name – Malpighiaceae. I’ve heard botanists shorten it to something that sounds like “Malpiggy,” which I suppose is correct enough for pronunciation, but which sounds, in English, unjust to the Italian scientist for whom the family was named: Marcello Malpighi, a 17th century anatomist. We humans have a Malpighi skin layer, and we have Malpighian corpuscles in our kidneys and spleen. So why is a plant family named for him? Because he also looked at “plant anatomy” under the microscope and wrote a book about what he saw – the Anatomia Plantarum.

One plant feature he must have described in some detail are plant hairs that are attached to a plant by the middle of the hair, not at either end. There’s a sketch at Plant Families of the Dominican Republic, a site, by the way, that has an excellent description of the Malpighiaceae family.

The sketch shows the characteristic clawed petals of the flower on the left, the Malpighian Hairs at the top right, and the winged fruit, like the maple wing, at the lower right. It’s worth taking a closer look at the vine flower and the nance flower to see these details.

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