Need CO2 for photosynthesis and give off O2.
Fertilized egg develops inside female gametangia and is thus protected.
4 major groups 1. Bryophytes are mosses, seedless and disperse by haploid spores 2. Seedless vascular plants are ferns, etc. Xylem carries water and minerals Phloem carries dissolved sugars, etc. Lignin strengthens cell walls Disperse by spores, diversified in Silurian and Devonian periods 3.