Excerpts from Jim Conrad's
Naturalist Newsletter

CASEARIA CORYMBOSA

from the January 10,  2010 Newsletter issued from Hacienda Chichen Resort beside Chichén Itzá Ruins, central Yucatán, MÉXICO
CASEARIA'S PELLUCID DOTS & LINES

Few woody plants are flowering during our early dry season. The small, white flowers and wavy or crenate-margined leaves of one tree bucking the trend is shown above. A close-up of that tree's B-B-sized flowers, which are a little unusual because they lack corollas so that their scoop-shaped, white sepals, or calyx lobes, perform petal service instead, is seen below:

CASEARIA CORYMBOSA, flowers

I'm not sure why so many of the flowers are turning brown and shriveling up. I suspect it's a disease or insect damage because other flower pictures on the internet don't show anything similar.

*NOTE: In 2016 I see that the species Casearia nitida has been lumped into the name CASEARIA CORYMBOSA.
The plant at hand is a shrub or small tree commonly and weedily growing throughout humid, lowland Central America and southern Mexico. It's CASEARIA NITIDA*, for which I can't find an English name. It's a member of the Flacourtia Family, the Flacourtiaceae, a family practically unknown to temperate plant-lovers but well represented in tropical regions. Casearia nitida is such a modest-looking, Plain Jane kind of tree that I wouldn't have bothered bringing it to your attention but for one thing:

If you hold one of its leaves up against the sun, you see the interesting details revealed below:

CASEARIA CORYMBOSA, pellucid dots and streaks of leaves

There you see a typical leaf's venation, but within the green areas between veins, the "lacunae", you see lots of bright dots and streaks. Several plant families display such dots -- the Citrus Family (Rutaceae), the Myrtle Family (Myrtaceae) foremost among them. However, those curved streaks are extraordinary. Botanists say that such translucing points are "pellucid." This pellucid dotting and streaking is fairly common in the Flacourtia Family.

Usually pellucid dots are glands filled with aromatic oils. Crush such leaves and typically they emit a pungent fragrance. Casearia nitida's leaves aren't particularly fragrant, though. Still, I suspect that they're filled with chemicals repulsive to insects.


from the August 13, 2017 Newsletter issued from Rancho Regensis north of Valladolid, Yucatán, MÉXICO
CASEARIA FRUITING
This week as I was climbing our new cement water tower I looked into the forest canopy and saw the interesting visual composition shown below:

CASEARIA CORYMBOSA, leaves and fruit

Not many trees line their leaves up so neatly along their branches, alternating them and keeping them in one plane. And look at the orange, cherry-like fruit at the top right. A cluster of several such fruits shows something unusual about their arrangement, as seen below:

CASEARIA CORYMBOSA, fruits

In contrast to those fruits, a cherry, for instance, bears beneath it a slender, pliable stem known as a pedicel, but here the fruit appears to arise from gnarly wood. I'm unsure what anatomists would say about this, but the appearance is distinctive. A broken open fruit showed what appeared to be three potential seeds, each in its own carpel, as seen below:

CASEARIA CORYMBOSA, fruit cross section

At first I couldn't place this species, but then something about the leaves encouraged me to hold the leaf against the sun and look closely with my handlens, and I saw what's shown below:

CASEARIA CORYMBOSA, leaf with pelllucid dots and streaks

Several plant families are capable of producing those pale or "pellucid" dots, especially the Citrus and Myrtle Families, but those elongated pellucid lines appearing with the dots is something special. When I see them, I think of the tropical Flacourtia Family, the Flacourtiaceae. And remembering that, I realized that I've already described this tree in its flowering state, as you can see above.

So, now we know what the small, warty flowers of Casearia corymbosa develop into.