SYNOPTIC DESCRIPTION OF THE PHYLUM PTERIDOSPERMOPHYTA (WARD 1904)
| EUKARYA> ARCHAEPLASTIDA> VIRIDIPLANTAE> STREPTOBIONTA> EMBRYOPHYTA> TRACHEOPHYTA> SPERMOPHYTA> PTERIDOSPERMOPHYTA |
PTERIDOSPERMOPHYTA LINKS
| The following description comes from Pearson (1995), Bold et al. (1987), and Bierhorst (1971). |
I. SYNONYMS: seed ferns
II. NUMBERS: all extinct
III. PHYLUM CHARACTERISTICS
- A. Structure
- Habit: The seed ferns are conifer-like with 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 (text with tooltip) A leaf is a specialized appendage that grows from a stem, and usually is the primary photosynthetic organ. Such appendages are of three types: enations, microphylls, and macrophylls (=megaphylls).
- 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. : Variable; grains with single slits, three slits; some saccate (text with tooltip) In the form of a sac. . Details of the microgametophyte are unknown.
- Microstrobilus: Absent, pollen-bearing synangia (text with tooltip) A Synangium is a structure made of two or more eusporangia fused together. occur on the leaves.
- Seeds: Details unknown.
- Megastrobilus: Absent, ovules (text with tooltip) An ovule is a structure that contains the megagametophyte in seed plants. The megagametophyte remains within the megasporangium (the nucellus), which is surrounded by layers of integuments. After fertilization, the ovule develops into a seed. are borne on the leaves.
- Stems: Generally woody, secondary xylem with bordered pits (text with tooltip) In a xylem-conducting cell, usually a tracheid, it is a pit in the secondary wall having a thickened rim (border). on the tracheids (text with tooltip) Tracheids are water-conducting cells that have rings of thickened wall. ; large leaf traces.
- Leaves: Large and frond-like.
- Roots (text with tooltip) A root is a plant axis without nodes and internodes, and it has a vascular stele that is different from that of the stem axis. : Cycad-like.
- B. Ecology: They are all extinct.
| LITERATURE CITED Banks, H. P. 1975. Reclassification of Psilophyta. Taxon. 24: 401-413. Bierhorst, D. W. 1971. Morphology of Vascular Plants. In: N. H. Giles and J. G. Torrey. The MacMillan Biology Series. The MacMillan Co. New York. Bold, H. C., C. J. Alexopoulos, and T. Delevoryas. 1987. Morphology of Plants and Fungi. 5th Edition. HarperCollins Publishers, Inc. New York. Cantino, P., J. A. Doyle, S. W. Graham, W. S. Judd, R. G. Olmstead, D. E. Soltis, P. S. Soltis, and M. J. Donoghue. 2007. Towards a phylogenetic nomenclature of Tracheophyta. Taxon 56(3): E1-E44. Dittmer, H. J. 1964. Phylogeny and Form in the Plant Kingdom. Van Norstrand Company, Inc. New York. Doyle, J. A. 1998b. Phylogeny of vascular plants. Annual Review of Ecology and Systematics. 29:567-599. Doyle, J. A. 2006. Seed ferns and the origin of angiosperms. Journal of the Torrey Botanical Society. 133(1): 169-209. [C] Hilton, J. and R. M. Bateman. 2006. Pteridosperms are the backbone of seed-plant phylogeny. Journal of the Torrey Botanical Society. 133(3): 119-168. Kenrick, P. and P. R. Crane. 1997b. The Origin and Early Diversification of Land Plants: A Cladistic Study. Smithsonian Institute Press. Washington, D.C. Linkies, A., K. Graeber, C. Knight, and G. Leubner-Metzger. 2010. The evolution of seeds. Tansley review. New Phytologist. 186: 817-831. Northington, D. K. and J. R. Goodin. 1984. The Botanical World. Times Mirror/Mosby College Publishing, St. Louis. Soltis, D. E., P. S. Soltis, and M. J. Zanis. 2002. Phylogeny of seed plants based on evidence from eight genes. American Journal of Botany. 89:1670-1681. Taylor, E. L. and T. N. Taylor, H. Kerp, and E. J. Hermsen. 2006. Mesozoic seed ferns: old paradigms, new discoveries. Journal of the Torrey Botanical Society 133(1): 62-82. Zhu, W.-Q. and P. Kenrick. 1999. A Zosterophyllum-like plant from the lower Devonian of Yunnan Province, China. Review of Palaeobotany and Palynology. 105: 111-118. |
| By Jack R. Holt. Last revised: 03/27/2013 |
