. Morphology of angiosperms (Morphology of spermatophytes. Part II). Angiosperms; Plant morphology. THE MICR0SP0RANGIU3I 29 It is reasonably assured, therefore, that cauline micro- sporangia occur in at least seven genera, both Monocotyledons and Dicotyledons being represented. Upon the whole, they seem more characteristic of the primitive members of these two groups than of the more highly specialized members, but this impression may disappear with further investigation. If the cauline origin of megasporangia be considered, the primi- tive character of this feature becomes increasingly uncert
Image details
Contributor:
The Book Worm / Alamy Stock PhotoImage ID:
RDXWEPFile size:
7.1 MB (482.7 KB Compressed download)Releases:
Model - no | Property - noDo I need a release?Dimensions:
2213 x 1129 px | 37.5 x 19.1 cm | 14.8 x 7.5 inches | 150dpiMore information:
This image is a public domain image, which means either that copyright has expired in the image or the copyright holder has waived their copyright. Alamy charges you a fee for access to the high resolution copy of the image.
This image could have imperfections as it’s either historical or reportage.
. Morphology of angiosperms (Morphology of spermatophytes. Part II). Angiosperms; Plant morphology. THE MICR0SP0RANGIU3I 29 It is reasonably assured, therefore, that cauline micro- sporangia occur in at least seven genera, both Monocotyledons and Dicotyledons being represented. Upon the whole, they seem more characteristic of the primitive members of these two groups than of the more highly specialized members, but this impression may disappear with further investigation. If the cauline origin of megasporangia be considered, the primi- tive character of this feature becomes increasingly uncertain, for cauline megasporangia are common even in the highest groups. It seems probable, therefore, that the cauline or foliar origin of sporangia among Angiosperms is not to be taken as an argument for or against the primitive character of the group in which they occur. The particular organ developing micro- sporangia was probably determined not by its morphological nature, but by what may be called its physiological relations (Fig. 6). Even among Pteridophytes, the sporangia of Lycopo- dium are foliar, and those of the nearly allied Selaginella cau- line ; and among Gymnosperms sporangia have both origins. It is evident, therefore, that the distinguishing morphological. Fia. 7.—Liliurn phttadelplucum. Transverse section of almost mature anther; nearly all the walls separating the microsporangia have broken down; highly developed stomium (s) and endothecium (with its nb-like thickenings) very prominent; x 25. —From a drawing by W. J. G. Land. structure is the sporangium rather than any member of the plant body from which it may arise. In most cases the stamen produces four microsporangia (Fig. 7), and the exceptions noted thus far are by no means. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.. Coulter,