Botany 620 - Field Trip Log
Koontz Bayou/Burleson County
26 March 1996

The Brazos River once ran well West of its current path, heading toward an area now occupied by the village of Clay, just North of Independence, Texas. The longest river in Texas encountered a wall of resistance at this point, a ridge of limey sandstone known as the Oakville Formation. This contact exposed the bedrock, forming a high bluff that, hundreds of years ago, overlooked the river. As is the case with a similar Oakville exposure (Moore's Hill) just East of Navasota, this site carries an unusual suite of plant taxa, many associated with the Edwards Plateau. These include the Texas persimmon, the Mexican Buckeye, and a a very strange Texas endemic that was not in flower during this first visit. This bi-generic anomaly, and many other 'outcrop' taxa, will be more evident when we revisit the bluff in a few weeks.

Koontz Bayou lies beneath the bluff. It stands as a remnant of the prehistoric contact between the 'Old River' and bedrock of the Oakville formation. Another remnant surrounds the bluff/bayou area. Old growth hardwoods of this immediate area, sheltered by topographic irregularity, provide an example of what was once a rich forest that extended throughout the alluvial plain of the Brazos River.

Beneath the tall trees, we encountered two understory taxa in flower:

Floral structure of these (perfect, well developed perianth [or bracts]) suggest animal pollination systems. We collected specimens from two other flowering trees that show floral structures associated with wind-vectored pollen (reduced perianth, unisexual); both produced opposite, compound leaves:


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Created on 28 March 1996