Ferns

These plants have big leaves, called fronds, they do not produce seeds and they generally need water to fertilize. For this reason they are generally found in humid and shady forests and in marshes.
On the underside  of  sporophyte leaves,  circular shaped organs called sori, containing  spores, can easily be seen . They  can  be of the same size or of different sizes (microspores and macrospores) and  when they germinate they can give rise to different gametophytes (male and female gametophytes). They often generate a single type of gametophyte,  a few centimetres in size, which grows on contact with water. Gametophytes are often heart-shaped and have only one layer of cells containing chlorophyll. Archegonia and antheridia are located in separate areas and they surround the gametes. The antheridia contain a large number of multiflagellated sperm, and if there is sufficient humidity, they spill out and make their way, by chemotropism, towards the archegonia. In the beginning the young embryo  feeds on the gametophyte, which in turn degenerates. Some ferns  grow up to 20 metres in height, and stand tall like trees.

 

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