In March the Lower Rio Grande Valley Sierra Club visited the largest remaining grove of Montezuma cypress trees (Taxodium mucronatum) in South Texas. These majestic trees are growing along the banks of a Brownsville, Texas resaca, an oxbow lake that was once a channel of the ancient Rio Grande. Enormous Montezuma cypresses once lined the banks of the river and all of the resacas that snake throughout Brownsville, but the wood was highly prized for its water resistance, and the trees were cut and used to build the wharves for early Brownsville’s port.
There are only a few large trees left along the Rio Grande watershed, and the Brownsville site is one of only 2 actual groves remaining. The cypress’s seeds need to float in water for a time in order to germinate, so the end of ancient natural flood cycles in the highly engineered watershed, along with the mowing of stream and resacabanks, has kept them from making a natural comeback.
The Rio Grande Valley is the northernmost range of the Montezuma cypress, which is the national tree of Mexico. The Aztecs called it ahuehuete, old man of the water, and once upon a time, when wetlands and resacas were plentiful around river systems, these “old men” grew to enormous sizes. They are, after all, in the same family as giant sequoias and redwoods. The “Tule Tree” in Oaxaca, Mexico is a Montezuma Cypress that has the stoutest trunk of any tree in the world. (It takes 17 people with arms outstretched to span its circumference!)
The City of Brownsville owns about half of the resaca and, thanks to the efforts of community activists, has recently agreed to protect it. Efforts are ongoing to secure the remaining portion of this amazing vestige of the ancient freeflowing Rio Grande.