Homeosis is defined as the complete or partial replacement of one part of an organism with another part. Double-flowered cultivars of H. rosa-sinensis display a divergent floral morphology that appears to fit the criteria for homeosis. The corolla of single flowered cultivars is pentamerous. Mature ...

A comparative developmental study of the compound leaves Ailanthus altissima, Lupinus polyphyllus, Fraxinus americana, Rhus typhina and the highly dissected leaves of Achillea millefolium, was initiated to document the changes in form that lateral elements (leaflets/lobes) undergo at later stages in...

The early stages of development of the inflorescence of Philodendron melinonii were examined using scanning electron microscopy. Pistillate flowers are initiated on the lower portion of the inflorescence and staminate flowers are initiated on the distal portion. The male flowers have four to five st...

Scirpus acutus Muhl. is a hardstem bulrush found throughout North American wetlands. The seeds of most species of Scirpus have a relatively low germination potential. Seed viability and the developmental morphology of the embryo upon germination were studied using standard tetrazolium (TZ) testing, ...

The Gulf of St. Lawrence aster, Symphyotrichum laurentianum (Fernald) G.L. Nesom (Asteraceae), a small annual halophyte endemic to disturbed and highly transient habitats in the Gulf of St. Lawrence, is classified as "threatened" by the Committee on the Status of Endangered Wildlife in Canada. Lepid...

In Philodendron, pistillate flowers are initiated on the proximal portion of the inflorescence and staminate flowers are initiated on the distal portion. Between the staminate and pistillate flowers, there is a transition zone consisting of sterile male flowers adjacent to the male zone and a row of...

In the spadix of Caladium, there is a clearly recognizable intermediate zone consisting of sterile male flowers. The transition between the female zone and the male sterile zone is more or less abrupt. During the early stages of development of the inflorescence, a few atypical bisexual flowers betwe...

Instead of alternating as is typical for the majority of flowering plants, the five stamens of Basella rubra are superposed to the five tepals. The first two tepals toward the abaxial side are initiated first, followed by the two tepals toward the adaxial side and the abaxial tepal that may be laggi...

The establishment of basic leaf shape in three representative members of the genus Vitis (Vitis riparia Michx., cultivars Vivant and Concord) was studied using scanning electron microscopy. At maturity, the leaves of the above taxa have specific and recognizable features which makes it possible to d...

In Angiosperms placentae or ovules are fomed on carpels or the floral apex. Hence, in a developmental sense, there are carpellate and acarpellate gynoecia. The latter occur in about 11% of all Angiosperm families. Basella rubra is an example of the noncarpellate condition. Its single basal ovule is ...

The larval stages of the cynipid wasp Diplolepis rosaefolii induce the formation of single-chambered, lenticular galls on the leaves of the wild shrub rose, Rosa virginiana. The development of galls induced by D. rosaefolii was studied using light and scanning electron microscopy. The gall consists ...

This modification to the technique of epi-illumination light microscopy makes use of a new system of lenses that replaces expensive and not readily available dipping cone objectives. The newer objectives offer at least comparable resolution and depth of field, along with simple preparation procedure...

The leaves initiated at successive nodes in the heteroblastic series in Leea guineensis seedlings become progressively more complex in construction. Leaves at the first four nodes are simple and are followed by transitional forms between nodes 5 and 7. These transitional leaf forms are compound in n...