External water is not required for fertilization in gymnosperms and angiosperms (spermatophytes). In pteridophytes fertilization takes place in presence of water. At the time of fertilization neck canal cells and ventral canal cell disintegrate forming a passage for antherozoids to enter inside. Water is essential to facilitate the act of fertilization in bryophytes. The male gametes or antherozoids swim through water and are attracted by the chemical of mucilagenous material secreted from archegonium. Group thallophyta includes the algae and fungi. The algae are mostly aquatic and the fungi are saprpphytic or parasitic.