Life Cycles

Life cycles differs in the duration of haploid and diploid phase. There are three types of life cycles:

(A) Haplontic life cycles:

(i) Gametophytes is dominant, haploid and independent plant body where as sporophyte is dependent on gametophyte and draws nutrition from it.

(ii) Maximum part of life cycle is represented by haplo-phases. E.g.  Spirogyra, Volvox, Chlamydomonas and Dinoflagellate.

(B) Diplontic life cycles:

(i) Sporophyte is dominant, diploid, independent plant body where as gametophyte is highly reduced and dependent on sporophyte.

(ii) Maximum part of life cycle is represented by diplo-phase. e.g., Fucus, Sargassum , All gymnosperms and angiosperms and  Diatoms etc.

(C) Haplo-diplontic/Diplohaplonitic life cycles:

(i) Nearly equal existence of sporophyte as well as gametophyte

(ii)Both of them are photosynthetic and free living.

e.g., Ulva, , All bryophytes, all Pteridophytes, Liminaria

(iii)Red algae have two or more phases in their life cycle called

• Haplobiontic/Haplohaplontic type
• Diplobiontic/Diplohaplontic type