On the Morphology and Anatomy of Turtle Grass, Thalassia Testudinum (Hydrocharitaceae). I. Vegetative Morphology

In an introductory account of the vegetative morphology of Thalassia testudinum König, a very constant organ symmetry is described. A horizontal long-shoot bearing only scale-leaves produces lateral buds alternately on opposite sides at regular intervals separated by 9 to 13 internodes. No buds are associated with intervening scales. Buds are opposite, not axillant to the subtending leaf and because of this unusual position and their precocious development it can be disputed that they are lateral. Buds become erect short-shoots bearing, initially, scale-leaves but soon, foliage-leaves. Long- and short-shoots have the same fundamental symmetry. Each is autonomous so that the one can only become the other by branching. Because of the absence of residual meristems, growth of Thalassia is largely dependent on activity of shoot apical meristems, even root production being limited to apical regions. In the absence of rhizome apices, isolated fragments do not regenerate.