The possible origin of peculiar Thalassia testudinum reported from Texas as Posidonia oceanica.

Abstract

Peculiar plant fragments of Thalassia testudinum were erroneously reported form Galveston and other localities in Texas as the Mediterranean Posidonia oceanica. These fragments may have originated from distant Caribbean or other Gulf of Mexico seagrass beds from which they were torn during a previous hurricane season. They probably owe their superficially somewhat posidonia- like form to the long oceanic transport. When studied in laboratory cultures with T. testudinum transplanted from local Texas seagrass beds and P. oceanica from the Mediterranean coast of France, the Gulf fragments produced leaves that were wider than is typical of Texas plants but similar to those produced by Thalasia of more tropical origin in Mexico and Central America. The flavonoid composition of the beach fragments also was similar to that of Thalassia.