Biol 120: Plant Biology
Lecture 4 Summary
Ferns and Fern Allies – Seedless Vascular Plants.
• The simplest of vascular plants – evolved alongside
bryophytes ~ 450-700mybp.
• Seedless Vascular Plants: vascular plants (plants with
xylem and phloem) that produce neither flowers nor seeds,
and are hence called vascular cryptogams. Instead, they
reproduce and disperse only via spores.
• vascular tissue: the tissue in higher plants that constitutes
the vascular system, consisting of phloem and xylem, by
which water and nutrients are conducted throughout the
• Sperm of ferns have tail-like structures and swim through
water to reach the egg – Therefore they are WATER
DEPENDENT for reproduction.
• Lignin: a complex organic polymer composed of chains of
glucose molecules, deposited in the cell walls of many plants
(incl. SVP), making them rigid and woody.
o Lignins allowed for an increase in size and height
• SVP account for only 5% of living plant species today.
• Psilotophyta – whisk ferns
• Sphenophyta – horsetails
• Pterophyta – Ferns
• Lycopodium – club mosses; ancestors of extinct Zosterophylls
• Isoetes - Quillworts
• Sporophyte is dominant
• Gametophyte is significantly reduced in size and short-lived
• Sporophyte is independent at maturity
• MOST Sporophytes are homosporous (releasing one type of
• Gametophytes can be bisexual or unisexual
• Heterosporous Sporophyte have megasporangia with
megaspores (large, becomes female gametop