Vegetative Branching in Thalassia testudinum (Hydrocharitaceae)-A Correction

Closer examination of horizontal scale-bearing rhizomes in Thalassia reveals that the branch meristem originates in a truly lateral position, but opposite a leaf very early in the second plastochrone of the main axis.

Abstract

Horizontal scale-bearing rhizomes in Thalassia produce, at fairly regular but distant intervals, lateral branches which develop into erect, leafy shoots. These branches are leaf-opposed, not axillary. Since they originate precociously and are at first equal to the main axis, it had been suggested that they are the result of an equal dichotomy of the shoot apex, a type of branching which has been recently demonstrated in two unrelated monocotyledons. Closer examination reveals that the branch meristem originates in a truly lateral position, but opposite a leaf very early in the second plastochrone of the main axis. Growth of the branch is rapid, and it establishes early continuity with the procambial system of the main axis. Main axis and branch are equal in size by the time each has developed two leaves above the level of branching. This gives an appearance of equal dichotomy. Subsequently, the branch is evicted into an obviously lateral position.