Excerpts from Jim Conrad's
Naturalist Newsletter

from the February 28, 2010 Newsletter issued from Hacienda Chichen Resort beside Chichén Itzá Ruins, central Yucatán, MÉXICO

For a couple of weeks pleasing, diffuse explosions of yellowness have adorned roadside woods edges, rather like Redbud-pink soon will appear up North, as shown below:


The small trees themselves are mostly leafless now, so the greenness in that picture is provided by other trees. If this yellow-flowered tree were planted alone in a park, it'd draw an audience, but here it's just a weed tree struggling for space. Once its flowers are dropped, it'll become just another nondescript tree. Up close, the blossoms, about the size of a US 25-cent piece, reveal the family the tree belongs to, as seen below:

Yucatan Caesalpinia, CAESALPINIA YUCATANENSIS, flower

And if that doesn't ring a bell, maybe the tree's twice-compound, or "bipinnate," leaf -- a little reminiscent of a Honeylocust leaf -- will, as shown below:

Yucatan Caesalpinia, CAESALPINIA YUCATANENSIS, leaf

If you see a flower with five petals arranged with bilateral symmetry, with ten stamens united at their bases into a cylinder around a slender ovary and stigma-tipped style, and the plant bears compound leaves like this, you just have to think "Bean Family," and that's the case here. Honeylocust and Redbud trees also are in the Bean Family, so it all hangs together.

Our yellow-blossomed tree is Yucatan Caesalpinia, CAESALPINIA YUCATANENSIS. We've run into several trees that burst into lavis yellowness like this, but they were usually Cassias, also Bean Family members and also with five-petaled, bilaterally symmetrical flowers. However, Cassia leaves are only once compound, or pinnate, as opposed to bipinnately, compound. If you can't visualize these leaf differences you might check out our leaf page at http://www.backyardnature.net/lf_confg.htm.

In the diagram at that page's top, Leaf A is a classic pinnately (once-pinnate) compound leaf. Leaf G, like our Caesalpinia leaf, is bipinnate.

from the April 30, 2017 Newsletter issued from Rancho Regensis north of Valladolid, Yucatán, MÉXICO

Several Yucatan Caesalpinias grow around the hut and nowadays they're attracting attention in an unexpected way. Below, you can see part of a tree in the current condition, its branches leafless for the dry season but bearing large numbers of short legumes:

Yucatan Caesalpinia, CAESALPINIA YUCATANENSIS, fruiting

The legumes are explosive. Here at the end of the dry season they are crispy dry and, especially in mid afternoon when the sun beats down the hardest, they are designed so that their two sides pull against one another until finally something snaps, the sides fly apart, and beans are thrown everywhere -- seed dispersal through legume detonation. A couple of unexploded legumes are shown below:

Yucatan Caesalpinia, CAESALPINIA YUCATANENSIS, legumes

An open legume displaying its beans is shown below:

Yucatan Caesalpinia, CAESALPINIA YUCATANENSIS, beans in legum

The snapping legumes can be heard from 20 feet and more away. Most of the day there are no snaps, but in mid afternoon when the sun shines brightest you might hear them every ten or fifteen seconds, so it's quite a performance. Our afternoons are partly cloudy, so part of the show is that the very moment a cloud covers the sun the snapping ceases instantly,but when the sun returns, so does the snapping.

Interestingly, a second tree at the ranch also produces snapping legumes, and it's also a member of the genus Caesalpinia, though it's not native to this area. That's the Dwarf Poinciana, Caesalpinia pulcherrima, much planted in the tropics worldwide because of its beautiful flowers. You might be interested in comparing the two species' blossoms -- in seeing two variations on the Caesalpinia theme. The Yucatan Caesalpinia's flowers appear at http://www.backyardnature.net/yucatan/caesgaum.htm

The Dwarf Poinciana's flowers are shown at http://www.backyardnature.net/yucatan/d-poinci.htm

from the February 18, 2018 Newsletter issued from Rancho Regensis north of Valladolid, Yucatán, MÉXICO

Nowadays this tree is doing something else worth paying attention to, shown below:

Yucatan Caesalpinia, CAESALPINIA YUCATANENSIS, leaves turned yellow

To anyone with memories of autumn in the Temperate Zone, this looks like a tree getting ready to lose its leaves for winter. But here we have no winter, so it's really getting ready for the worst part of the dry season, which is starting now. This tree's leaves are the most brightly colored of any woody plant I can think of down here, and it feels odd seeing one our hotter afternoons. Many woody species lose their leaves in advance of the dry season, but normally their green leaves simply fall off, or develop certain brown parts on them, or become a pale, slightly yellowish-green hue before dropping, but nothing like this.

Not all Yucatan Caesalpinias here are yellow now. The one in the picture is especially colorful. Some trees of the species are still dark green and some have lost every leaf on them. Others are mostly leafless, with a few yellow leaves still hanging on. Some of the leafless trees bear slender arrangements of immature flower buds, promising to produce spectacularly yellow-flowered trees such as those shown on our page.