The members of Phaeophyceae (brown algae) store mannitol as a reserve food material.

(a) Haplontic life cycle It is exhibited by Volvox, Spirogyra and Chlamydomonas. The dominant photosynthetic phase in these plants is gamotophytic phase which develops from a haploid spores after a mitotic cell division of zygote.

(b) Diplontic life cycle is found in gymnosperms and angiosperms. The dominant phase is diploid sporophyte plant develop from zygote.

(c) Haplodiplontic life cycle It is an intermediate conditions exhibited by bryophytes and pteridophytes. Here haploid gametophytic stage alternates with diploid sporophytic stage.

Roots are represented by root like structure called rhizoids in less developed lower plants (bryophytes and pteridophytes). The plant tissue system in these is not differentiated into true leaf, stem and roots as it is found in higher plants (gymnosperm and angiosperm).

Haplo diplontic type of life cycle is exhibited by Ectocarpus, Polysiphonia and Kelps. Here, diploid saprophytic phase alternate with haploid gametophytic phase. In Fucus, the main plant body is saprophytic and it shows diplontic type of life cycle.

In bryophytes the male sex organ is antheridium and female sex organ is archegonium. The gametophyte ( n ) in bryophyte bears the primiture sex organs in the form of antheridium (male) which produce flagellate antherozoids which are male gamete and need thin film of water to swim and reach female reproductive organ (archegonium).

Archegonia is female part which has single egg cell. Both these reproductive parts are born on male and female, anthridiophore and archegoniophores borne on haploid gametophyte.