Reproduction

 

Life Cycle of Conium maculatum; an Angiosperm

 

     The photo showed below depicts the process that Conium maculatum goes

 through in order to reproduce. Conium maculatum is classified as an angiosperm.

As an angiosperm, this life cycle alternates between that of a diploid sporophyte

 generation (2n) and a haploid gametophyte generation (n). This is called an

 alternation of generations.     

     Angiosperm plants

 are considered to be

 heterosporous

 because they have

 two different spores,

 the microspore and

 megaspore. The male

 organs of the plant

(the anthers) contain

 diploid spores that are

 called microsporocytes.

 These microsporocytes

 undergo the process of

 meiosis in order to divide

 and produce

 haploid microspores. The female organ of the plant (the carpel) houses a few

 different structures such as the ovule, ovary, stigma and style. Within the ovule,

is a single diploid megasporocyte (2n) that divides through the process of meiosis

in order to produce four haploid megaspores. Of those four haploid megaspores,

only one survives.

     After each microspore undergoes mitotic division, a pollen grain is produced.

The pollen grain is the haploid, male gametophyte which is called a

 microgametophyte (n). The surviving megaspore goes through mitotic division

 in order to produce haploid cells that are called megagametophytes (n).

     The pollen grain will then work to pollinate the female parts of the flower. This

 process starts as a pollen grain lands on the stigma and germinates. A pollen tube

 then grows down through the style until it encounters the female gametophyte.

 At this point, double fertilization will occur. The sperm will then fertilize the egg

into a diploid zygote (2n) and also fertilize a large cell located in the center that

 contains two polar nuclei, into a triploid (3n) cell.

     The zygote will then start the next sporophyte generation as it develops into an

 embryo. Meanwhile, the triploid cell develops into the endosperm, a necessary

 component that provides nutrition for the developing embryo. As the seed

 germinates, the sporophyte will mature and start the process all over again.

Another plant that reproduces this way is saw palmetto. Check it out! 

 

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