Know all Angiosperms

Angiosperms

 The seeds are unclosed in fruits.

 Smallest Wolffia to tall or Eucalyptus ( over 100 meters).

 The dicotyledons are characterised by seeds having two cotyledons, reticulate venations in leaves,

and tetramerous or pintamerous flowers, i.e, having four or five members in each floral whorls.

 The monocotyledons on the other hand are characterised is single cotyledons seeds, parallel venation

in leaves, & trimerous flowers having three members in each floral whorls.

 Each ovule has a megaspores mother cell that undergoes meiosis to form four haploid

megaspores.

Three of then degenerate and one divide to from the embryo sac. Each embryo – sac has a

three – called egg apparatus – one egg cell & two synergids, three antipodal cells and two

polar nuclei.

 one of the male gamete fuses with the egg cell (syngamy) to from a zygote.

 Produces the triploid primary endosperm nucleus (PEN). Because of the occurrence of two fusions i.e,

syngamy & triple fusion, this event is termed as double fertilisation, an event unique to angiosperms.

 Meiosis in the zygote results in the formation of haploid spores. Many algae such as Volvox,

spirogyra & some species of Chlamydomonas.

 An algae, focus sp. All seed bearing plants i.e, gymnosperms & angiosperms.

 Bryophytes and pteriophytes, interstingly, exhibit an intermediate conditions. (Haplo – diplontic)

both phases are multicellular . however, they differ in their dominant phases.

 All bryophytes represent this pattern.

 All pteridophytes exhibit this pattern.

 While most algae genera & haplontic.

 Ectocarpus, pblysiphonia, kelps are haplo – diplontic. Fucus, an algae is diplontic.