Female gametophytes produce a carpogonium with a trichogyne. Spermatia unite with the trichogyne, an auxiliary cell becomes the zygote. Alga is oogamous. Zygote grows into a carposporophyte attached to female gametophyte. Carposporophyte produces mitospores called carpospores.
Carpospores settle out of water column and grow into tetrasporophytes.
Tetrasporophytes are isomorphic to gametophytes. Tetrasporophytes produce tetrasporangia in which meiosis takes place. Tetraspores produced by meiosis are shed to the water. Tetraspores settle out of the water column and grow up into gametophytes. Division Phaeophyta Rhodophyta Nucleus Eukaryotic Eukaryotic Wall Pectin Cellulose Alginic Acid Pectin Cellulose Carrageenan Agar, etc.