Red berried Allophylus

In May of last year, the red berries of a small tree that grows near our bodega caught my eye. I particularly liked how the red showed up against the light green, attractive leaves.

It’s a small tree that usually has, in this area, several slender trunks growing together, like an overgrown shrub.

At the time, I made a few stabs at finding out what it was, but never got very far.

Then, this year, I saw a truly bizarre growth on the tree and decided it was time to get serious about identification, if for no other reason than to give me some ammunition in tracking down what the growth was.

The complexity of the leaves
The first clue I’ve learned to note is the complexity of the leaves: are they simple or compound? For example, take this clipping from the tree I’m interested in:

Is this three separate leaves, or is it one leaf divided into three “leaflets”? And how can you tell?

The key is to look for the bud. If there is a bud near the base of each of those three “leaves,” then we would have simple leaves – two of them opposite each other and one at the end of the “stem.”

But that is not the case here. The bud is found at the base of the stalk that bears all three “leaves,” or, to be correct, the petiole that bears all three leaflets.

So, this is a compound leaf, consisting of three leaflets. Such leaves are usually called trifoliate leaves. In fact, in my limited experience, if I see a leaf arrangement consisting of three parts, I feel pretty confident that it is a compound leaf, a trifoliate leaf. But I always check for the bud, just to make sure.

The arrangement of the leaves
My next clue is the arrangement of the leaves. Are they opposite, alternate, or whorled? From the image above, you can get a pretty good idea that the leaves alternate their way up the stem. Here’s confirmation:

So, the first two clues to identifying this tree is that it has trifoliate, alternate leaves.

Unusual combination
The combination of trifoliate leaves and an alternate arrangement of them along the stem of a tree is a combination so unusual in the neotropics that Gentry lists only four genera (in four different families) plus a few genera in the citrus family that have this combination.

So I went through the list and easily eliminated most of the candidates: one had latex (this tree does not), one had spiny trunks and branches (this tree does not), and the members of the citrus family have translucent dots on their leaves and have a citrus-like odor (this tree has neither).

Of the two remaining genera, Allophylus seemed the better candidate. Allophylus leaves have toothed edges, and the leaf tip is more pointed than blunt. The other candidate had crenelated edges and blunt tips to the leaves.

The soapberry family
Allophylus is a member of the Sapindaceae family, also called the soapberry family. Earlier I had found a liana (a woody vine) that was identified by botanists at the Smithsonian Tropical Research Institute as Serjania atrolineata, which was also a member of the soapberry family. It is called that because the fruits of one genus in that family are used as soap, but more representatives of the family have a toxic latex or sap that is used as a fish poison. Indeed, the berries of one species of Allophylous is used as fish poison in New Ireland (Mabberley).

In Panama, lianas such as Serjania are the most numerous representatives of the Sapindaceae family. There are only five genera of trees, and of these genera, only Allophylus has trifoliate leaves (Woodson et al.)

The Allophylus genus
It takes only two characteristics to sort out the three species of Allophylus that occur in Panama: 1) whether the leaf is smooth or fuzzy with small hairs, and 2) the size of the fruits.

The leaves of this tree are quite smooth, but if you turn them over, you see small tufts of plant hairs at the angles made by the veins, especially the main, or mid-, vein and its secondary veins.

Two of the species have these tufts, so the next characteristic to look at is the size of the fruits.

This fruit is about 7 mm in diameter (and, no, I don’t know what those two bumps are):

These characteristics identify the species of this tree. It is Allophylus psilospermus. The fruits of this species ripen “…from yellow to orange, finally red and glabrate [smooth] at maturity.” (Woodson et al.) The next picture shows the ripening fruits and gives another view of the tufts on the underside of the leaves.

Distribution

Allophylous psilospermus is found throughout Central America and northern South America.

Although it occurs in ecologically variable climates, including tropical dry forests such as found in our area, it is most commonly found in Panama in the wetter parts of a tropical wet forest (Woodson et al.)

What’s in its name?
I have not been able to find a common name for Allophylous psilospermus, but it is possible to break down its scientific name to get at what the botanist was thinking when he  (Linneaus gave the genus name, Ludwig Adolph Timotheus Radlkofer gave the species name) named it. The Latin definitions are from the Dictionary of Botanical Epithets and from Pond Plants Latin.

The genus name, Allophylus, is from

• allo = different
• phyll = leaf, foliage

The species name, psilospermus, is from

• psilo = smooth
• spermus = seed

Thus we have a different leaved, smooth seeded tree, but I can’t imagine creating a common name from that description.

Allophylus and The Thing

So, after feeling pretty confident about my identification of Allophylus psilospermus, I went looking for some description of the growth that shows up on many of these trees. I’ve already described how I failed at that endeavor. The growth does seem to be a form of witches’ broom disease, though, and I’m concerned about how many instances I’m seeing among our several Allophylus psilospermus trees. I was interested that Woodson et al. mentioned that the species most commonly occurs in the wettest areas of wet forests, and I’ve begun to wonder whether the tree is slightly stressed in our drier climate.

Whether stressed or not, I’m quite fond of our Allophylus psilospermus, and look forward to the time, which should be soon now, that all the berries are ripe and red.