Year: 1985
Type: article
Abstract: The ovary, ovule and megagamelophyte at the mature gametophyte stage have been observed for, and compared among, 131 species chosen to represent all the subgenera, sections and most of the subsections of Rhododendron.Gametophyte and early endosperm development has been followed in 14 of the species.Considerable variation occurs in ovary size, shape, indumentum, carpel number, ovule number, placental characteristics, ovule orientation, wall thickness, etc.Similarly, the ovules, though basically alike in type throughout the genus, differ in size, shape, proportion of ovule occupied by the gametophyte, thickness of integument, length of micropyle, presence of appendages, etc., while the gametophytes, which all develop according to the Polygonum pattern and have a similar complement and arrangement of cells, do differ in size, proportions, amount of starch, some cellular details, etc.Although the indumentum types on the ovary show an essentially similar distribution among subgeneric taxa as do those on the leaves, it has not been possible to discern other features, singly or in clusters, which could serve to arrange groups of species in clearly distinguishable subgeneric taxa, whether newly erected ones or those presently recognized on other grounds.Wide variation occurs in most characters among the several species observed in each of the larger sections-Vireya, Rhododendron and Hymenanihes.Although the range of variation in any one section overlaps with that in the others, each section displays, on the average, a somewhat different expression of a set of ovary and ovule characteristics.Vireya, particularly, shows a number of features which regularly occur together in most species and are found only spasmodically, and individually, in species of other sections.The several subgenera and sections of the azalea complex, each represented by many fewer examples, are even more difficult to characterize on the basis of ovary and ovule.'See text for sources of classification used. 2 Letters used to identify subgenus and/or section in text and figure legends.Relatively complete development seen for one species.
Author: Barbara F Palser
Language: English
Topic: Plant Reproductive Biology
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: bronze
OpenAlex ID: W4414701800