Seedless Vascular Plants

Seedless Vascular Plants

• Earliest Vascular plants
• Have true roots and stems
• Have true leaves
• Exhibit alternation of generations, However sporophyte (2N) generation is now dominant over gametophyte (N) generation.
• 4 major divisions
• Division Pterophyta - Ferns
• Division Psilophyta - Whisk ferns
• Division Lycophyta - Club Mosses
• Division Sphenophyta - Horsetails

Division Pterophyta: The ferns.

General Form

• Found throughout the world-more frequently in tropical areas.
• Adult sporophyte has a long horizontal stem called the Rhizome.
• Rhizome is vascular
• Fronds extend upwards from rhizome
• Roots extend downwards from rhizome

Life Cycle

• Spores are released from small structures underneath sporophyte fronds called sori (sorus)
• Spores grow into the gametophyte generation called the Prothallus
• Is heart shaped, ~2cm across.
• Contain archegonia (egg) and antheridia (sperm) similar to mosses.
• Sperm fertilizes egg via rain, sporophyte grows from within archegonia

Fern Life Cycle

Division Psilophyta: The Whisk ferns.

• Similar to ferns in life cycle
• Sporophyte generation develops a "forked" branching pattern called dichotymous branching.
• Leaflike structures lack vascularization

Division Lycophyta: The Club Mosses

Club Moss

• Are usually smaller.
• Life cycle differs from ferns in that gametophytes are either male or female, not both.
• Archegonia are produced on female gametophyte.
• Antheridia are produced on female gametophyte.

Division Sphenophyta: The Horsetails

• Characterized by jointed stems
• Have "Cone-like" structures at tips of stems