HAPLONTIC
HAPLO-DIPLONTIC
DIPLONTIC
LIFE CYCLES OF ORGANISMS
A life cycle is a period involving one generation of an organism through means of reproduction, whether through asexual reproduction or sexual reproduction.
Alternation of generations (also known as metagenesis or heterogenesis) is the type of life cycle that occurs in plants thathave distinct haploid sexual and diploid asexual stages.
are small, non-vascular plants, such as mosses, liverwortsand hornworts. They play a vital role in regulating ecosystemsbecause they provide an important buffer system for otherplants, which live alongside and benefit from the water andnutrients that bryophytes collect.
Bryophytes
mosses liverworts hornworts
Bryophyta
•The term Bryophyta came up from the word ‘Bryon’ which meansmosses and phyton meaning plants.
•These are the plants that grow in shady and damp areas and are smallin size.
•They lack vascular tissues.
•They reproduce through spores instead of producing flowers andseeds.
•The study of bryophytes is called Bryology.
Why are Bryophytes CalledAmphibians of Plants?
•Bryophytes are called “amphibians of the plant kingdom” becausethey’re the terrestrial plants but require water to finish their life cycleat the time of sexual reproduction.
Classification of Bryophytes
•According to the newest classification, Bryophyta is split into threeclasses:
•Hepaticopsida (Liverworts)
•Anthocerotopsida (Hornworts)
•Bryopsida (Mosses)
A pteridophyte is a vascular plant (with xylem andphloem) that disperses spores. Because pteridophytesproduce neither flowers nor seeds, they are sometimesreferred to as "cryptogams", meaning that their means ofreproduction is hidden.
Pteridophytes
Ferns Club Mosses Horsetails
Pteridophytes
•Pteridophytes are vascular plants and have leaves (known as fronds), rootsand sometimes true stems, and tree ferns have full trunks. Examplesinclude ferns, horsetails and club-mosses. Fronds in the largest species offerns can reach some six metres in length!
•Many ferns from tropical rain forests are epiphytes, which means they onlygrow on other plant species; their water comes from the damp air or fromrainfall running down branches and tree trunks. There are also some purelyaquatic ferns such as water fern or water velvet (Salvinia molesta) andmosquito ferns (Azolla species).
•Pteridophytes do not have seeds or flowers either, instead they alsoreproduce via spores.
•There are around 13,000 species of Pteridophytes.
Classification of Pteridophytes
There are four classes, namely:
1.Psilopsida
2.Lycopsida
3.Sphenopsida
4.Pteropsida
Pteridophytes Life Cycle
any vascular plant that reproduces by means of anexposed seed, or ovule. The seeds of manygymnosperms (literally “naked seeds”) are borne in conesand are not visible until maturity.
Gymnosperm
Conifers Cycads Ginko
Gymnosperms
•Gymnosperms are seed-bearing vascular plants, such as cycads,ginkgo, yews and conifers, in which the ovules or seeds are notenclosed in an ovary.
•The word "gymnosperm" comes from the Greekword gymnospermos, meaning "naked seeds". Gymnosperm seedsdevelop either on the surface of scale or leaf-like appendages ofcones, or at the end of short stalks.
•The largest group of living gymnosperms are the conifers (pines,cypresses and relatives) and the smallest is ginkgo, a single livingplant species found in China.
•There are around 1000 species of gymnosperm.
Gymnosperm Life Cycle
Angiosperms are plants that produce flowers and bear theirseeds in fruits. They are the largest and most diverse groupwithin the kingdom Plantae, with about 300,000 species. ...Angiosperms also comprise the vast majority of all plant foodswe eat, including grains, beans, fruits, vegetables, and mostnuts.
Angiosperms
Angiosperms
•Angiosperms are seed-bearing vascular plants.
•Their reproductive structures are flowers in which the ovules areenclosed in an ovary. Angiosperms are found in almost every habitatfrom forests and grasslands to sea margins and deserts.
•Angiosperms display a huge variety of life forms including trees,herbs, submerged aquatics, bulbs and epiphytes. The largest plantfamilies are Orchids, and Compositae (daisies) and Legumes (beans).
•There are an estimated 352,000 species of flowering plantsor angiosperms.
Dicot vsMonocot
Summary of the monocotphylogenetic tree, indicatingfamilies
