ABSTRACT
Algae are eucaryotic, unicellular or multicellular organisms and mostly occur in aquatic environments. The algae produce a disc-like thallus which is multi-layered in the centre and single layered in the periphery. The cells have chlorophyll and carotenoid as photosynthetic pigments and cell wall contains cellulose, xylan, mannan, etc. It grows between the cuticle and epidermis of the host and very rarely between epidermis and palisade cells. Algae produce many sterile hairs (setae) and sporangiophores (sporophores) on the thallus after rupturing the cuticle or epidermis. The zygote produces a dwarf sporophyte consisting of a stalk bearing one or more cells. Each cell has a small dehiscent microsporangium. After meiosis each microsporangium releases four quadriflagellate ‘microzoospores’.
