SYNOPTIC DESCRIPTION OF THE PHYLUM CYCADEOIDOPHYTA (BOLD ET AL. 1987)
| EUKARYA> ARCHAEPLASTIDA> VIRIDIPLANTAE> STREPTOBIONTA> EMBRYOPHYTA> TRACHEOPHYTA> SPERMOPHYTA> CYCADEOIDOPHYTA |
CYCADEOIDOPHYTA LINKS
| The following description comes from Bold et al. (1987) and Bierhorst (1971). |
I. SYNONYMS: cycadeoids, Bennettiales
II. NUMBER: all are extinct
III. PHYLUM CHARACTERISTICS
- A. Structure
- Habit: The cycadeoids are cycad-like seed plants with barrel-shaped stems and large frond (text with tooltip) A frond is a leaf that emerges by unrolling (as in the fiddleheads of ferns). This type of leaf emergence is called circinate vernation. -like leaves. All plants are extinct.
- Pollen (text with tooltip) The collective mass of grains produced within the anthers of flowering plants or the male cones of a gymnosperm. In all seed plants, pollen is generated by the development of a microspore into a microgametophyte. The germination of the pollen grain leads to the development of a pollen tube, which delivers two sperm or sperm nuclei to the egg in the ovule. In flowering plants, mature microgametophyte has only two cells, a tube cell and a generative cell. : Pollen grains are similar to those of the Cycads.
- Microstrobilus: Microsporophylls are often fused at the base; technically a simple strobilus (text with tooltip) A strobilus is an axis of fertile appendages. A simple strobilus is an axis of sporophylls. A compound strobilus is an axis of simple fertile axes. Sometimes the compound cones have simple fertile axes that are reduced to a single sporophyll and appear to be simple strobili. which bore both ovulate and pollen-bearing structures.
- Seeds (text with tooltip) Unit of sexual reproduction in some plants. Formed when an ovule is fertilized and comprised of outer coat that encloses stored food and an embryo. : Appear to be similar to those of Cycads.
- Megastrobilus: In bisporangiate cones, ovules occur on a central receptacle; the structure suggests either a high degree of self-pollination or a high degree of animal-assisted pollination.
- Stems: Very similar to those of the Cycads.
- Leaves: Large and frond-like.
- Roots: We do not know.
- C. Ecology: All plants are extinct. Their fossil history dates from the late Permian to the Cretaceous. They were very abundant during the Mesozoic.
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| By Jack R. Holt. Last revised: 03/27/2013 |
