EEB340 Lecture 16.docx

42 views2 pages
12 Apr 2012
School
Course
Professor

For unlimited access to Class Notes, a Class+ subscription is required.

Lecture 16: Alternation of Generations
Alternation of Generations
Psilotum
Equisitum
Ferns (leptosporangiate)
Homosporous
Heterosporous
Leptosporangiate Ferns
- sorus is an aggregation of sporangia
- come sori are convered by an indusium covering over the sporangium protects
the sporangia
- indusium dries and shrivels so mature spores better able to be dispersed into the
environment
- diversity in how sori are arranged on the sporophyll
- different modes of maturation of the sporangia some allow for gradual
maturation so that spores may be produced over longer period of time
- sori may be sitting on leaf margin
- false indusium: leaf margin curling to protect the sporangia
- annulus is the function equivalent of the endothecium
o cell wall thickenings help them bend back when dry
o stomium is a small cell and area of weakness that allows for splitting of
sporangium endothecium
- fern gametophytes are variable in morphology
- these ferns are heterosporous
Water Ferns
- water ferns are also heterosporous
- sporocarp: highly reducted leaf, functionally a sporophyll
- sporocarps develop in assocation with the megaphylls
- Marsilea 4 leaf clover water shamrock
- The sporocarp is heavily scalarified
- The sorophore is the lower layers of the sporocarp cell walls have tons of pectin
in them; cells swell with water once sporocarp has imbibed water
- Sorophore is where sori develop
- Each sorus develops a megasporangium and 2 microsporangia
Unlock document

This preview shows half of the first page of the document.
Unlock all 2 pages and 3 million more documents.

Already have an account? Log in

Get access

Grade+
$10 USD/m
Billed $120 USD annually
Homework Help
Class Notes
Textbook Notes
40 Verified Answers
Study Guides
1 Booster Class
Class+
$8 USD/m
Billed $96 USD annually
Homework Help
Class Notes
Textbook Notes
30 Verified Answers
Study Guides
1 Booster Class