1. Life on Earth Kingdom Plantae Part II
Rhyniophyta and Lycopodiophyta
Cooksonia

2. Introduction
Sporophyte generation (2N) is the photosynthetic, conspicuous generation
All members have evolved specialized tissues for water (XYLEM) and food (PHLOEM) conduction
Groups continue to become better adapted to the terrestrial environment

3. Evolutionary Lines PLANT KINGDOM “bryophytes” “vascular plants”
“green algae”

4. Evolution of Non-Seed, Vascular Plants

5. Early Devonian Landscape (about 400 million years ago)

6. Reconstructed Early Devonian Landscape
Cooksonia
Aglaophyton
Zosterophyllum
early lycophytes
Psilophyton

7. Phylum: Rhyniophyta
Known from fossils more than 400 million years old (all extinct today)
Sporophytes had no roots or leaves
Sporangia produced only one kind of spore (homosporous)
Example:
Rhynia (found in chert beds in England)

8. Phylum: Lycophyta Plants with true roots and microphyllous leaves
Some species produce compacted sporophylls into a cone or strobilus
Some genera are homosporous (Lycopodium and Huperzia) others are heterosporous (Selaginella and Isoetes)

9. Heterospory vs. Homospory
HOMOSPOROUS PLANTS
gametophyte generation with archegonia AND antheridia (monoecious)
spores
male gametophyte with antheridia
female gametophyte with archegonia
HETEROSPOROUS PLANTS
megaspores
microspores
dioecious
gametophytes

10. Lycopodium Common in New England and the Great Lakes Region
Often used for Christmas decorations (evergreen)
Spores were once used as photographic flash powder

11. Lycopodium (strobili)

12. Selaginella
Species are heterosporous with microsporangia and megasporangia
Megaspores develop into female gametophytes
Microspores develop into male gametophytes
Large group with tropical, temperate and desert species

13. Selaginella rupestris

14. Selaginella with strobili

15. Selaginella striboli
megasporangium
microsporangium

16. Selaginella strobilus

17. Selaginella (sporangia)
megasporangium
microsporangium

18. Selaginella lepidophylla

19. Isoetes Commonly known as “quillworts”
Each microphyllous leaf is a sporophyll, either a microsporophyll or a megasporophyll (heterosporous)
Stem is a fleshy “corm”
Often grow at the margins of ponds and lakes

20. Isoetes

21. Isoetes microsporangium

22. Isoetes

23. Isoetes melanopoda (Nebraska)

24. Lepidodendron Known as the fossil “scale tress”
Common forest giant of the Carboniferous Period
Helped to form present day coal deposits

25. Carboniferous Forest Reconstruction

26. Lepidodendron

27. Base of Lepidodendron (Stigmaria)