A Protocorm of Ophioglossum

Abstract

1. The protocorm is nearly spherical, with a circular pit in the center of the top. This pit extends downward about 0.8 of the diameter of the protocorm, and the apical cell is located at its bottom. 2. The bases of the leaves are attached to the sides of this pit, with the oldest at the top. The functioning leaf is the seventh, and the primordia of six others occur below it. 3. The vascular cylinder is an everted ectophloic siphonostele with endarch xylem. The leaf trace consists of two strands which attach separately to the cylinder. The roots are numerous and outside the cylinder. 4. The apical cell is a triangular pyramid. The segments divide twice longitudinally before a transverse division occurs. The segments enlarge below more rapidly than above, and the eversion of the cylinder results from this. 5. The segments of the apical cell of a rhizome of O. vulgatum divide transversely first; the later divisions are irregular. The upper and lower portions of a segment enlarge uniformly. 6. The vascular t...