Plant Kingdom - Classification and Characteristics

Alginic acid or alginate is found in the middle lamella and primary cell walls of sea weeds such as, Laminaria, Macrocystis, Ascophyllum, etc.

Cyanobacteria (blue-green algae) were first photosynthetic organisms. They contain photosynthetic lamellae equivalent to thylakoids hence, these are autotrophic.

Red algae secrete and deposit calcuim carbonate and appear like corals.

The thallus of Volvox is hollow ball like flagellate colony. It is called as coenobium.

The development of diploid gametophytes from the vegetative parts of the diploid sporophyte without the intervention of spores is known as apospory.Apogamy is the development of sporophyte directly from the gametophyte without the intervention of sex organs and gametes.

Protonema is prostrate, branched, multicellular, filamentous structure, which bears erect foliose gametophore. Protonema is produced on germination of a moss (bryophyte) spore, from which new plants develop as buds.

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Column I Column IIAnthoceros HornwortAdiantum Walking fernSargassum AlgaeProthallus GametophyteAsterales Inferae

Pteridophytes are vascular cryptogams. They generally produce spores but do not produce seeds.Bryophytes are non-vascular but spore forming cryptogams.Gymnosperms and angiosperms are vascular and seed forming phanerogams. All seed forming plants are also known as spermatophytes.

 Pinus is a gymnospermic plant. Ovulves of pinus are uncovered, which lie on the megasporophyll, hence this plant does not have flowers. However, it produces seeds like other three plants mentioned, all of the other three are angiosperms.

After fertilization, the ovary develops into fruit and ovary wall forms the fruit wall (pericarp). But gymnosperms have naked seeds because in gymnosperms, ovary (pericarp) is absent.

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Calyptra is a covering developed from the venter of archegonium in bryophytes and pteridophytes. It acts as a transpiration shield around the immature capsule and provides protection to the young capsule.

In Pinus, the pollen grains at maturity are protected by a three-layered wall; outermost is exine, the second exointine forms two balloon-like outgrowths called wings and the third is intine. Wings help in the transportation of pollen grains from one place to another place.

Old pine (Pinus) stumps are still being distilled to some degree as a source of turpentine and resin.

Ginkgo biloba is a gymnospermic plant. It is also known as living fossil because it has a great fossil history.

Pteridophytes include ferns, horsetails, clubmosses, spikemosses and quillworts.

Bryophytes are known as ‘amphibians of plant kingdom’ because they can adapt to both land and water habitats. In their vegetative structure, bryophytes completely adapt to the land habitat. However, they still depend upon water for sexual reproduction because the swimming habit is retained by their sperms.

Vegetative reproduction in Funaria takes place by fragmentation of primary protonema, secondary protonema, gemmae, bulbils and apospory.