SYNOPTIC DESCRIPTION OF THE PHYLUM PROGYMNOSPERMOPHYTA+
| EUKARYA> ARCHAEPLASTIDA> VIRIDIPLANTAE> STREPTOBIONTA> EMBRYOPHYTA> TRACHEOPHYTA> PROGYMNOSPERMOPHYTA |
PROGYMNOSPERMOPHYTA+ LINKS
| The following description comes from Bold et al. (1987) and Bierhorst (1971). |
I. SYNONYMS: progymnosperms
II. NUMBER: all are extinct.
III. PHYLUM CHARACTERISTICS
- A. Structure
- Gametophyte: Not known.
- Sporophyte: Tree-like with monopodial branching (text with tooltip) Monopodial growth is characterized by extreme overtopping which produces a large central stem with smaller lateral branches. .
- Spores: Homosporous (text with tooltip) Homosporous (adj) plants produce one type of spore. to heterosporous (text with tooltip) Heterosporous plants have sporangia that produce spores of different sizes: megaspores (large) and microspores (small). Megaspores produce archegoniate gametophytes, and microspores produce antheridial gametophytes. ; some are saccate (text with tooltip) In the form of a sac. .
- Sporangia: Thick-walled eusporangia (text with tooltip) A eusporangium is the most common spore-bearing structure in plants. Eusporangia develop from more than one cell and usually have a wall of several cell layers. Contrast a eusporangium with a leptosporangium. at the ends of fertile branches or on the adaxial (text with tooltip) This is derived from two Latin roots that mean toward (ad) the axil (axis). Adaxial is an adjective most often used to describe the leaf surface that is on top or that surface which faces the apical meristem. side of fertile appendages.
- Stele: Eustelic; very conifer-like; with wood and bordered pits.
- Leaves: Frond-like lateral branch systems to simple leaves in Archaeopteris.
- Roots: Present.
- B. Ecology: Plants are extinct.
| LITERATURE CITED 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. Kenrick, P. and P. R. Crane. 1997b. The origin and early diversification of land plants: a cladistic study. Smithsonian Institute Press. Washington, D.C. Rothwell, G. W. 1999. Fossils and ferns in the resolution of land plant phylogeny. Botanical Review 65:188-218. Rothwell, G. W., W. L. Crepet, and R. A. Stockey. 2009. Is the anthophyte hypothesis alive and well? New evidence from the reproductive structures of Bennettitales. American Journal of Botany. 96(1): 296-322. Tomescu, A. M. F. 2008. Megaphylls, microphylls and the evolution of leaf development. Trends in plant science 14 (1): 5-12. |
| By Jack R. Holt. Last revised: 03/26/2013 |
