Excerpts from Jim Conrad's
Naturalist Newsletter

Palo de Caja, ALLOPHYLLUS COMINIA, flowers & fruits

from the January 18, 2015 Newsletter issued from Río Lagartos, on the north-central coast of Yucatán, MÉXICO

On the trail into El Zapotal, the isolated reserve maintained by the Mexican environmental Group Pronatura, in extreme northeastern Yucatán State, a bush with slender, arching stems was laden with maturing fruit and I couldn't place it. It's shown above.

I've seen such small, red-ripening, succulent fruits arranged in panicles on wooden stems before, but notice that this plant's leaves are composed of three leaflets arising from atop a stiff petiole -- they're "trifoliate," like clover leaves. In my mind, such fruits in panicles on woody plants just don't go together with trifoliate leaves. Only a handful of woody plants bear trifoliate leaves. The fruits look like those of the Nightshade Family, so one was squished to see if it contained several tomato-like seeds, which it didn't, as seen below:

Palo de Caja, ALLOPHYLLUS COMINIA, fruit with seed exposed

It was a drupe with a single, hard seed, like a cherry. Cherry trees are members of the Rose Family, but the Rose Family is mostly of the Temperate Zone, and not a single Rose Family member is listed for the Yucatan. After a good deal of cogitating the closest I could come to such a plant was the Brazilian Pepper Tree, Schinus molle, which produces similarly small, red, spherical, drupe-type fruits in panicles on woody stems. However, that tree's leaves are compound, not trifoliate.

Still, making that association helped me focus on the part of the Phylogenetic Tree of Life where such plants reside. Brazilian Pepper Trees belong to the Cashew/Poison Ivy Family, the Anacardiaceae, but nothing in that family occurring in the Yucatan looked like our plant. Browsing nearby branches of the Tree and discarding those with only Temperate Zone species, soon I came to the Soapberry Family, the Sapindaceae, a big tropical family of mostly woody plants, often climbing, and leaves mostly compound, including trifoliately compound ones. Looking on the Internet at species in that family occurring in the Yucatan, it wasn't long until a good match came up: the genus Allophylus.

We have two look-alike Allophylus species, and after a lot of image comparisons I'm pretty sure that ours is the one more commonly found in the Yucatan, ALLOPHYLLUS COMINIA. In Spanish it's often called Palo de Caja, more or less meaning Box Bush. ,

Palo de Caja is distributed from southern Mexico south through Costa Rica and in the Caribbean area. Cuba's Agricultural Ministry claims that extracts from Palo de Caja can be used to control diabetes by diminishing glucose levels, plus they are antioxidant and anti-inflammatory.

You can imagine that birds relish the succulent flesh. In our picture, many fruits appear to have been removed as they matured.