Excerpts from Jim Conrad's
Naturalist Newsletter

from the December 21, 2014 Newsletter issued from Río Lagartos, on the north-central coast of Yucatán, MÉXICO

Nowadays the little road following the coast just south of Río Lagartos is beautified by the presence of a dense, small tree with dark green leaves and abundant yellow blossoms, as shown below:


The thumbnail-size yellow flowers are arranged in a clutter of lanky racemes bunched at branch tips in the manner shown below:


That picture shows that the foliage consists of compound leaves divided into fairly large, roundish leaflets. One of the twice-compound leaves with its leaflets broadly rounded and notched at their tips instead of ending in sharp points is shown below:

Mareña, CAESALPINIA VESICARIA, compound leaf

Seeing such a twice-compound leaf on a tree, the first plant family to come to mind is naturally the big Bean Family, so at this point in our analysis of who this tree might be we begin looking for other Bean Family features. A glance at the flowers leaves us a little hesitant, as you can see below:


If the flower had been of the classic Bean Family "papilionaceous" kind -- with large upper petal, two side petals, and the two lower petals fused along their common margins into a scoop-like shape, and with stamen filaments united into a cylinder around the ovary's style -- we'd have absolute confidence that our tree belongs to the Bean Family. However, the sepals, which in most flowers are small and green, here are large and yellow like the petals, plus the petals are only vaguely papilionaceous, and the stamens don't have their filaments united into a cylinder.

And yet, the pretty roadside tree is in fact a member of the Bean Family. It belongs to that minority of Bean Family species segregated into the subdivision, or subfamily, of species with flowers similar to ours -- flowers that can give the impression of exhibiting a transitional state between the bilaterally symmetrical, papilionaceous flowers of most Bean Family species, and flowers in other plant families whose flowers show radial symmetry. The Bean Family subfamily our roadside tree belongs to is the Caesalpinia Subfamily, the Caesalpinioideae.

Our roadside tree is itself a member of the genus Caesalpinia, the large and important genus providing the subfamily its name. It's CAESALPINIA VESICARIA, in Mexico occurring only in the Yucatan Peninsula, but extending beyond the Yucatan through the Caribbean and south to Costa Rica. There's no good English name for the tree but in the Yucatan it's called Mareña, meaning something like "She, of the sea."

"Mar" is "sea," and the suffix "-eña" means "coming from, related to, or like." The tree is so pretty that it's sometimes sold as a tropical ornamental under the name Large-leaved Caesalpinia, but that's such an anemic handle that we can't let it displace the lovely "Mareña."

In the Bahamas, Mareña has been used medicinally to treat low blood pressure, and at one time the wood was exported to the US as a source of reddish dye. Some freshly splintered stems from a Mareña soaked for two days in water at room temperature produced the reddish brew shown below:


If I'd boiled fresh heartwood maybe the color would have been more vivid. Mareña wood's tinted water isn't as bright as some colors we've tested the same way, but still it's a color and back when humanity was hungry for textiles colored other than dingy gray, Mareña's reddish dye must have been appreciated.

from the February 8, 2015 Newsletter issued from Río Lagartos, on the north-central coast of Yucatán, MÉXICO

Nowadays Mareña is as conspicuously loaded with legume-type fruits as earlier it was heaped with flowers, as shown below: