He’s been keeping an eye out on this tree for us, and I thought I’d pass along to you his report.

Ok… time to update on the algarrobo garment renewal…

Here is the algarrobo with its new set of green chemistry labs, ready to process winter mineral carrying fluids from the ground and continue reaching out to the sun.

Nice tree, isn’t it?

Here is a closer look at the chlorophyll labs, and… what is that brown thing amidst the leaves?

Let’s take a a closer look…

Looks like some nectar sucking poisonous flying bugs have set up residence among the new foliage. A closer look at the creatures shows them peeking out their residence’s aperture. Wonder what they make of the camera flash?

Before getting entranced with the wasps, I’ll pipe in here with a reminder from John’s first report and also a couple of other observations.

In his first report, John told us that the scientific name of the tree is Hymenaea courbaril. and that it is in the family Fabaceae, subfamily Caesalpiniodieae.

Fabaceae is the bean family, which means the tree has compound, alternate leaves. If you need a refresher, there’s a pretty complete description of the bean family in the post on macano, The Living Fence. In the case of the algarrobo, the compound leaves consist of two leaflets. The subfamily is the one with the large frilly flowers, such as the Flamboyant tree.

The genus name, Hymenaea, is named for Hymen, the god of marriage. It refers to the leaflets, which occur in pairs (Botanary). The species name, curbaril, is one of the common names for the wood of this tree (Vozzo).

The tree that has just now put out green leaves will flower starting in March and continuing through July. The fruits will ripen the following year, between February and May (Carrasquilla). If you go back to John’s first image, the one with the brown leaves, and click on it to enlarge it, you will see a large kidney-bean shape in the tree. That’s last year’s fruit, due to ripen any day now.

Here’s what John has to say about the tree and its fruit:

It is an extraordinary tree, in many respects; and the fruit is one of the richest food sources you can find. Some people don’t like the smell, or taste, but I was brought up with it. When you open one of the pods, take the dry fleshy pits out and take a good sniff of the inside of the pod… I find it wonderful. But I don’t care for Roquefort or such.

So it’s about time we started watching for the fruit at the local markets, yes? And see for ourselves if we like it, yes?

Meantime, about those wasps…

There is a great variety of them in Panamá; big, small, mean, docile, with all sort of dwellings, but I have never read anything about them. For example, take a look at another bug aerodrome…

These critters always build their entrance atrium looking south.

And look at these guys… they build into walls and such, and are always curious about who is around their den… A while back I witnessed a war between these critters and ants.

Take a look at this aerial combat, between two varieties of bees…

Anyone who knows anything about the wasps or bees around here is welcome to speak up. These are fascinating abodes.

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.

The plant loses its leaves – is deciduous – in the dry season, so the flowers are easily seen on the bare branches in this photo on the left taken in January. Yet in July when the leaves are out you can, with a judicious zoom (right), also see the flowers. Clearly, flowers can be present in both the dry season and the rainy season, but during the dry season they seem to be fuller and more abundant.

The Leaves
The leaves are compound – 3 leaflets for every leaf stalk or petiole. They are arranged on the stem in an alternate fashion, although some of the petioles are so close together on the stem that it is hard to see whether they are opposite or alternate in arrangement. Both these characteristics – compound leaves and alternately arranged leaves – are typical of the Fabaceae family.

The Tree
The tree can reach 10 m or 32 ft in height, which I believe this old one may have done – if it hasn’t exceeded it.

Sometimes I have to pause – a tree like this in the bean family?

Well, yes, because of those alternate, compound leaves, and because the fruits are, after all, beans, as you can see in this image of all parts from the Tree Atlas of Panama.

I learned the scientific name of the machetito from Carrasquilla‘s book Trees and Shrubs of Panama – it is Erythrina rubrinervia. But how did botanists know to place it in the Erythrina genus?

First, we know now that the flower puts it in the pea subfamily of the bean family (the Papilionoideae subfamily of the Fabaceae family).

Next, we know that it has compound leaves with 3 leaflets per leaf stalk. This makes it a trifoliate leaf. Within the pea subfamily, the only tree genus with trifoliate leaves is Erythrina (Gentry). So, that was easy. Erythrina it is.

Erythrina – red colored
The genus name, Erythrina, means red-colored. There are about 112 species in the tropics worldwide, and about 36 in Mexico and Central America (Neill, Ann. Mo Bot Gardens). The species extends into South America, and some time ago it was taken to Hawaii and cultivated there.

rubrinervia – red veined
The species name also contains reference to the color red, but what veins are they talking about? The leaf veins don’t look red to me.

After studying all the images at the Tree Atlas of Panama site, I found this close-up of the leaf stalk (petiole) which shows glands at the base of each of the leaflets, but which also shows red streaks on the petiole. They aren’t true veins but they give that appearance.

So we have a red-colored flower with red streaks on the petioles, giving us Erythrina rubrinervia. It’s incidental that the beans are also red.

Darwin’s interest
Darwin studied Erythrina species of plants, among others, when he was investigating how plants move. He found that the leaves of Erythrina and other species “sleep” at night, by drooping toward the plant stem. During the day the leaves orient themselves to be perpendicular to the rays of the sun in early morning and late afternoon and “edge-on” to the rays of the sun at midday (Project Gutenberg EBook). There’s a great sketch of the process at the web site of faculty member Thomas Herbert at the University of Miami.

Now let’s get back to that machete-shaped flower.

Hummingbirds
Whenever you see a long, narrow flower, you may suspect that hummingbirds pollinate these flowers, and this is true for the Erythrina genus as a whole, whose flowers are particularly rich in nectar. In our area, the larger hummingbirds – the Swallow-tailed Hummingbird and the Black-throated and Green-breasted Mango visit Erythrina (wikipedia).

These are long-billed hummingbirds. But if you should see a short-billed hummingbird at an Erythrina rubrinervia, you may yell “Thief! Thief!” because it has been shown that while long-billed hummingbirds pollinate the flowers, short-billed ones steal the nectar (Cotton, in Biotropica)

The Little Machete
So the little machete tree is filled with wonders – its bean-ness, its red-ness, the way it moves, and its relationship with hummingbirds. Watch for it next time you pass a living fence.

Others have not been so remiss, and I’d like to point you to the current Berry Go Round – Issue #12 – that’s being hosted at Foothills Fancies. Plenty of good reading about plants, nicely put together.

Way back at Thanksgiving this year, the Trees, Climate and People blog posted their botanical guide to Thanksgiving dinner. It’s a list of 42 plants with their common names, their scientific names and families, and the dish(es) they appeared in. I missed it at the time, but I love the concept and am passing it along in case you’re interested in compiling your own botanical guide to any holiday meal.

John Bennett sent a message about the tree known in Panama as algarrobo. There’s a town named Algarrobos on the road that goes from Dolega to David, and I’ve been meaning to stop there and look around, assuming I’ll find some of those trees. They’re probably also here in Potrerillos, but I thought my chances of actually encountering one would be better in a town named after them.

Here’s what John had to say back on December 8, 2008:

“Dry season or our winter is almost here, time to shed leaves and prepare for the dry spell. Unless you happen to be an “algarroba” tree. Or Hymenaea courbaril L. – Family: Fabaceae-caesalpinioideae – Sinonims: Nombres Comunes: Algarrobo, algarroba, guapinol, in which case you simply change to dry season leaves, which I suppose have less stomata and therefore loose less H2O.

“As you can see, the leaves are turning brown and soon they will all rain down on us and the tree will bring forth new green leaves, as if it were spring. In spring it will do the same.”

The Wikipedia article refers to the tree as Jatobá. Thanks, again, John, for your contribution and your interest.

Another project that has been swallowing a lot of time is the installation of a weather station and the putting together of a web site to publish the data. The installation went smoothly, but right now I’m waiting for an adapter that will let me plug the radio receiver into the USB port on my computer. While waiting, I’ve been fiddling with the web site, so I hope that by the time the part arrives, I’ll be able to get the weather data online very quickly.

So, on this last day, may I wish you a prosperous and peaceful New Year, and may we all be just as productive as we’d like to be!

   Hi-res

Now the beans are here. They started appearing a few weeks back, but there was one bean here, another way over there in another tree. Now there are several beans in each tree, but still the beans are scattered lightly and are not as strikingly visible from a distance as you might think from their colors.

Look at how the beans are still attached to the pod, even though they’re not within the pod itself. This appearance might be a way of luring birds to the tree to disperse the seeds (Zuchowski) although few birds seem to be attracted to these beans. All members of the bean family have complex seed coats, but the coats of these beans are actually simpler in anatomy than that in other beans. They are called “overgrown” or “overgrown-like” beans and the value or function of this feature is not yet known (Maumont).

If you click on the left image below, you’ll see some more dangling beans, whereas the pod has not yet opened in the image on the right.

Family: Fabaceae (bean family – alternate compound leaves)
Subfamily: Mimosoideae (mimosa subfamily – the flowers have many stamens)
Tribe: Ingeae (from Inga, the ice cream bean)
Genus: Cojoba (the Taino Indian word for the leaves)
Species: rufescens (becoming red)

More on this tree at the original post.

Update:

Our gardener found a young coral snake in the weeds along the fence. He killed it with his machete and then brought the decapitated corpse for to us to see. It doesn’t have any yellow on it at all – its colors are simply red and black, as in the Cojoba bean. I don’t know what species this snake is – wikipedia lists three genera and many, many species for coral snakes. But here it is for your viewing pleasure:

PS – The species is probably Micrurus multifasciatus, a coral snake of two colors and the most common in Panama. Information from Panamá: Puente Biológio [Panama: Biological Bridge], by Stanley Heckadon-Moreno.

And here’s a representative thorn:

We now have plans to remove at least the stands near the house.

Nevertheless, I continue to marvel at how the leaves shrink upon touch. And now I’ve read a very interesting post at Niches explaining exactly how and why the leaves shrink. He has some nice pictures, too. Definitely worth reading if you’re at all curious about this famous sensitive plant.

For me, it’s often the flower. I’ll be aware of a plant in the background, but when it blooms, then I really pay attention.

For the Cojoba tree, though, it was the leaves that made me stop and look. Toward the end of February, while the leaves of all the trees on the west side of our orchard wall were in various shades of green, the leaves of one kind of tree suddenly had a soft, rufous look.

The leaves themselves were attractively arranged, swooping down like giant bird feathers. The foliage made a nice contrast to the other trees, and I decided to watch for any sign of flowering to help me learn more about the tree. I thought I could guess already what family it belonged to, though. Those bird feather leaves were the biggest clue.

One of the easiest ways to start recognizing plant families in the tropics is the method developed by Alwyn Gentry. You decide first whether the leaves are

• simple (only one blade is attached to the stem) or
• compound (more than one blade is attached to a stalk, and that stalk is attached to the stem).

[This distinction is discussed in some detail here.]

Then you decide whether the leaves are

• opposite (leaf stalks or petioles are on opposite sides of the stem) or
• alternate (leaf stalks are found first on one side of the stalk, then the other, as they make their way up the stem).

Cojoba‘s leaves

In the case of Cojoba, the leaves are compound and alternate.

When you have this combination, you then examine the nature of the compound leaves. Are they arranged like bird feathers (pinnate) or like fingers on a hand (palmate), or are they found in groups of three (3-foliate)? If the leaves are pinnate, you need to decide whether they are simply pinnate or bipinnate. We already saw that these leaves are somewhat like giant bird feathers, so we know they are pinnate. In the case of Cojoba, they are simply pinnate.

Finally, count the blades on the leaf stalk to see whether you have an even or an odd number. Most of these leaves have 10 blades, some have fewer, and some have 12. So we have an even number, which means these are even-pinnate leaves.

Here’s our combination of leaf characteristics, then:

• alternate
• compound
• even-pinnate

Gentry lists only 4 tropical families with this combination of traits, one of which is the palm family. I read his descriptions of the other 3 families, and the one that best fits is the Fabaceae family, or the bean family.

I looked at the Fabaceae family in some detail when talking about the living fence tree, the macano. The bean family is very large and is divided into three subfamilies: the mimosa subfamily, the cassia subfamily, and the pea subfamily. To decide which of these subfamilies this tree belongs to, I needed to wait until it bloomed.

First flowers

The first flowers that I saw were on March 2, but before I got a decent picture, the rain had “wilted” them. About three weeks later we finally had another bloom.

These round balls of stamens immediately told me that the tree belonged in the mimosa subfamily. [Check here if you don't know why.]

When I went back to Gentry I had every reason to believe that this tree belonged to the genus Inga. Gentry stated that Inga is “…unique in being even-pinnate and with glands between all leaflets.” I went looking for the glands, and there they were (click on the image if you need to see a larger version):

The purpose of these glands is obscure. It’s possible they offer nectar to ants to keep the ants away from flowers, but the secretions from such glands may be resinous, gummy, or aromatic. I don’t know why these glands are here.

Inga is the ice cream bean tree

At any rate, I was very excited to think that this tree might be an Inga. It produces long pods with a juicy, white pulp that tastes a little like vanilla ice cream. To learn which Inga it might be, I turned first to Trees, Shrubs, and Palms of Panama, which is a database maintained by the Smithsonian Tropical Research Institute. It has descriptions and images of most of the recognized plants in the country. Not every plant has every feature pictured, however, and I found nothing that seemed to fit this tree.

Next I turned to my friend Carla, of Heliconia fame. She has a book of all the Ingas in Costa Rica, and she sent me a very good key, but, again, I could not find a match.

It’s not Inga – it’s Cojoba

Finally, I sent off some images to the kind botanist of Tropical Plant Guides, Robin Foster, who has been of great help to me in the past. He identified the tree as Cojoba rufescens. He made me feel a little better, though, when he said that it was often confused with Inga. Indeed, when I returned to Trees, Shrubs, and Palms of Panama to look up Cojoba rufescens, I read this paragraph on how to recognize it:

Compound leaves with an even number of leaflets (no terminal leaflet), and a gland between each leaflet pair, characterizes the entire genus Inga, as well as Abarema and some other related genera. Cojoba rufescens is fairly readily recognized, though, by the undulate leaflets, a consistent trait which is not found in Inga.

Cojoba has undulate leaflets

Here are the wavy edges, which, admittedly, are more obvious in real life than in these scans of the leaflet tops (left image) and bottoms (right image). The first image in this post also gives you an idea of the undulations.

The description also states that the leaflets near the base are reduced in size, which you can see here. Further the trunk may be “leaning and branched near the ground.”

Trunk branched near the ground

Here it is. The ground is hidden from view by other vegetation, but you can see several branches of the trunk here.

And finally, “when there are fruits, Cojoba is unmistakable.” I’ll have to wait to get my own picture of the fruit, which is a bean, but here’s the image from the Smithsonian. The bean has a red pod.

The coral snake bean

And finally we get to the name of the tree: Cojoba rufescens. Dave’s Botanary gave me the name for rufescens, which means “becoming reddish.” I believe that must be in reference to the leaves. But nowhere could I find the etymology of the word Cojoba.
Finally, I turned to the Integrated Taxonomic Information System (ITIS) and its report on Cojoba. The expert botanist listed there kindly replied to my query and said that the Taino Indians of the Caribbean called the dried leaves of this plant Cohiba or Cojoba.

The Cojoba genus is found in the West Indies, Central America and into South America.

The species C. rufescens, though, has not been reported from the West Indies, but is distributed throughout Central America with a few reports from western South America.

Panamanians have two common names for C. rufescens: guabito and coralillo (Carrasquilla). Guaba (guabito means “little guaba”) is the ice cream bean! So even though the red, curly bean of Cojoba looks nothing like the ice cream bean – which is long, brown, and thick – the leaves look enough like the ice cream bean tree to be named after it.

The other common name, though, comes from the bean itself. Coralillo is the Spanish word for coral snake, which has alternate bands of red and black. The twisty bean, with its red pod and black beans, which adhere to the pod even after it opens, must look pretty fierce in the tree!

And when you get up close to the flowers on a sunny morning, their exuberance can take your breath away.

The petals drop off quite easily, leaving a yellow snow on the ground.

Macano trees are part of the living fences in our area, although other species also are seen. Post-and-wire fences around here are really “stick” or pole-and-barbed-wire fences. Many of the poles are of macano wood. Soon (often within a year) after a pole is sunk into the ground, it starts sprouting.

Here’s rectangle A, showing the shoots, and the barbed wire attached to the pole:

Rectangle B shows the arrangement of the leaves, which are typical of the bean family. We’ll return to that arrangement later.

Macano trees are slow-growing but may reach a height of 20 meters (> 60 ft). The wood is strong and valued not only for fence posts but for tool handles, carvings, and multiple other uses. In fact, it is so treasured, that recently when we had ordered macano posts for a new fence (to keep our dog in and neighboring horses out), the order could not be completely filled because the wood had become unavailable. When it became available again, it was at a price 150% of the original! So, I was not surprised to notice one day that a post that had grown into a mature tree had itself been harvested for wood:

Notice the splintered top of the post, showing how recent the harvest is, and notice that the bottom three rows of barbed wire have been overgrown by the tree. The top two rows were obviously added later. (These features are easier to see if you click on the image to enlarge it.) Let’s look at why the macano is in the legume, or Fabaceae, family. Third Largest Plant Family Fabaceae (formerly called Leguminosae) is the third largest plant family in the world, with about 18,000 species. It is divided into three subfamilies, two of which have been discussed here earlier:

• the Mimosideae, which have flowers that look like soft spiny balls, with about 2,400 species and
• the Caesalpinioideae, which have brightly colored, showy flowers, with about 2,700 species, which includes the Senna and the Flamboyant trees.
• the Faboideae, the largest subfamily, with nearly 13,000 species.

It is this third subfamily to which the macano tree belongs. The flowers are Papilonaceous, which means they look like butterflies, but they are familiar to most of us as the distinctive flower of peas. These three subfamilies were organized originally mostly by the shape of the flowers, so let’s look at the shape of the pea flower to see why the macano belongs to the Faboideae subfamily with Papilonaceous flowers. The Pea Flower Here’s a diagram of a generic pea flower, copied from the Wildflowers and Weeds web site above (or next to, depending on your browser) an image of a flower from a macano tree. I don’t think there’s any doubt that we have a pea flower here.

What all Legumes have in Common Regardless of their flower shape, all members of Fabaceae have at least the following three things in common, and many of them have the fourth thing as well:

1. compound leaves – explained below – often pinnate (like a feather)
2. pods – such as edible beans and peas
3. nitrogen fixation – particular bacteria living in special root nodules transform nitrogen from the air into usable fertilizer forms of nitrogen
4. moving body parts (most) – pods that snap open (some beans), leaves that fold on touch (mimosa), tendrils that “feel” for a new place, or reproductive parts that spring out of the keel of a pea flower when an insect enters.

The macano has all these features, although I can only illustrate the leaves and give a sense of how the reproductive parts are tightly coiled in the keel, enabling them to spring out. First, the compound leaves.

Leaves are always attached to a stem. This may seem obvious until you look at an arrangement like this one from a macano tree. Here, small leaves are attached to a stalk, or axis, which in turn is attached to the stem. These small leaves, then, are not true leaves because they are not attached to the stem. They are leaflets, and the arrangement of leaf axis containing leaflets is called a compound leaf. Tip: You can tell whether you have leaflets or leaves if you watch for the buds of new leaves. The bud always appears at the place where the leaf will form. The buds of the macano do not appear along the leaf axis, but appear along the stem. A bud for a simple leaf will give rise to one leaf. A bud for a compound leaf will give rise to a leaf axis with several leaflets on it. This is how we know that the macano has compound leaves, like the good legume family member that it is. Now, for the contents of the keel – the moving body parts. I took a macano flower and tore it apart to look inside the keel. Here’s what I found:

I’m not sure I can describe the sensation of breaking open the keel. It had a longitudinal slit so it wasn’t hard to open, but when I separated the two sides, it felt like a minor explosion between my fingers. I didn’t know what had happened until I read later about the coiled spring for the reproductive parts. I wonder what insects experience when their mere presence causes the flower to burst open with an array of pollen-bearing parts! The macano’s pods give the plant its scientific name, Diphysa americana. Di- meaning two; -physa meaning bladders in Greek. The sides of the outer layer of the pods have two inflated chambers. I haven’t seen the pods yet, but when I do, and get a picture, I’ll post it here. As far as the nitrogen fixing parts of macano, well, I’ll have to take the scientists’ words for that. I think it’s neat, though, that where macano fence posts have sprouted, the soil will be enriched over time. Diphysa americana It was easy to find the scientific name of macano: both books Tropical Plants of Costa Rica (Zuchowski) and Trees and Shrubs of Panama (Carrasquilla) have good descriptions and pictures of the tree. Carrasquilla gives ‘macano‘ as a common name in Spanish. I was also able to find a pdf file on the internet that gives the complete botanical description of the species [Flores & Marin]. The following points come from that paper, with my own images to illustrate the points. The species extends from Mexico to Panama, commonly on flatlands or moderate slopes in tropical dry florests at elevations of 5 to 800 m. Its trunk is rarely straight.

The bark is brown or grayish brown, fissured, and rough.

We have already seen that the leaves are compound. They are also alternate – which means the leaf axes are not on opposite sides of the stem but climb up it in a staircase manner – and odd pinnate – which means there are an odd number of leaflets (between 11 and 21 for Diphysa americana), not an even number. The leaflets themselves are thin, soft, flexible, smooth, hairless, with toothless edges and rounded tips, shiny on top [left image] and almost grayish below [right image].

The image on the right, above, also shows the warty, longitudinal lenticels (areas on the surface of a twig). Click on the image for a larger view. The flowers occur in small, loose racemes, which are elongated clusters of flowers, shown at the beginning of this post, and for easy reference, below:

If you click on the image for a larger view, you’ll see that the green sepals that embrace the petals have a bell shape and you may be able to tell that there are 5 unequal lobes to this structure. The petals are deep yellow – pretty similar to the color shown by the camera. Inside the keel, as mentioned earlier, are the reproductive parts, the pollen-bearing stamens and the single female style.

The pod, when it appears, will be stalked, flattened, and pale brown. I suppose if you think you’ll be needing some ready cash in the distant future, and want to invest in macano wood, you might start looking for these pods in a few weeks and plant some seeds. Better yet, and perhaps faster, find a macano stick and plant it in the ground!