HIERARCHICAL CLASSIFICATION OF THE PHYLUM PROGYMNOSPERMOPHYTA+
| EUKARYA> ARCHAEPLASTIDA> VIRIDIPLANTAE> STREPTOBIONTA> EMBRYOPHYTA> TRACHEOPHYTA> PROGYMNOSPERMOPHYTA |
PROGYMNOSPERMOPHYTA+ LINKS
| The following system is a modification of Bold et al. (1987) and Bierhorst (1971). Form genera are given in brackets. |
CLASS PROGYMNOSPERMOPSIDA+
- ORDER ANEUROPHYTALES
- These plants are extinct with a fossil history through the middle to upper Devonian. They grow as small trees with dichotomously branched (text with tooltip) Dichotomous branching is the simple pattern of branching in which each node produces two equal branches. , leaf-like branch tips. Sporangia are terminal on the ultimate branches. They are homosporous (text with tooltip) Homosporous (adj) plants produce one type of spore. .
- Aneurophyton, Tetraxylopteris.
- ORDER PROTOPITYALES
- These plants are extinct and represented by a single genus. They are found in the lower Mississippian. They form trees and the stele has endarch protoxylem. The plants likely are 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. .
- Protopitys
- ORDER ARCHAEOPTERIDALES
- These plants are extinct with a fossil history which ranges from the middle to upper Devonian to lower Mississippian. These plants have simple megaphylls (text with tooltip) An megaphyll (=macrophyll) is a leaf that is derived from a lateral branch system which became webbed. Most extant vascular plants have macrophylls. on leafy branches which arise from the axils of rachial leaves on the secondary branches. Their growth habit is very conifer-like with strong monopodial (text with tooltip) Monopodial growth is characterized by extreme overtopping which produces a large central stem with smaller lateral branches. growth and extensive wood. The plants are heterosporous with sporangia borne on the adaxial side of the leafy branches.
- Archaeopteris [Callixophyton], Svalbardia, Actinoxylon, Siderella, Actinopodium]
| 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 |
