Ovuliferous Structures of Taxus canadensis

Abstract

1. The ovuliferous bud arises in the axil of a leaf early in the season, and matures the next year. 2. The ovuliferous organ consists of the primary shoot and the secondary shoot with the ovule. 3. The primary shoot is to be regarded as a vegetative branch of limited growth, bearing only reproductive axes (secondary shoots). While of limited character, at times it may become a functional vegetative shoot like any other vegetative branch. 4. The primary shoot is a persistent structure, functional for several successive seasons. 5. Occasionally the primary shoot may be terminal to a leafy branch. 6. The secondary shoot consists of three pairs of decussate scales and a terminal ovule. 7. The ovule arises as a direct continuation of the axis, there being nothing in its origin to indicate that it is a lateral structure. 8. The archesporium arises from the hypoderm. The sporogenous tissue consists of a considerable mass of cells, out of which one or two may function as megaspore mother cells. 9. The aril is regarded as the morphological fleshy layer of a 3-layered seed coat, delayed in appearance and physically separate from the hard stony layer. 10. The ovule receives its vascular supply direct from the axis cylinder, contrary to any axillary nature, and in harmony with the view that it is a cauline structure.