Saturday, July 27, 2013

Embryophyte Adaptations to Life on Land

For plants, making the leap to land and all the changes it entailed is arguably one of the most important evolutionary feats to date. Not only was this beneficial to them, it paved the way for land animals. Formally known as embryophytes because of the fact that the embryo sporophyte is protected my the parent gametophyte, land plants literally make our lives possible.

There are a few important adaptations that allowed embryophytes to thrive outside the relative comfort of watery environments. This article should give you a good understanding of these important difference between land plants and their algal precursors. It should come as no surprise the the majority of the defining characteristics of embryophytes are those that enable them to survive on land and successfully reproduce.

Alternation of Generations
Land plants have a life cycle which alternates between a multicellular gametophyte and sporophyte stage. Although this is seen in some algae, it is not a process used by charophytes, which are believed to be the group of algae most closely related to land plants.

Multicellular, Dependent Embryo
Zygotes within the gametophyte eventually form the multicellular embryos. These are in turn fed and protected by the parent plant. This in fact is what gives embryophytes their name.

Multicellular Gametangia
The gametes of land plants are produced within multicellular organs called gametangia. Archegonia are the female gametangia, which produce eggs and the sperm are produced by antheridia.

Walled Spores
Plant spores are encased within a tough polymer known as sporopollenin to protect them, allowing dispersal through dry air. These spores are produced by the sporophyte from organs called sporangia.

Apical Meristems
This refers to the undifferentiated cells of plants which become roots, stems, leaves and other structures. The growth of plant apical meristems are continuous as long as the plant lives.

This video (after the jump) provides some more helpful information. Enjoy!

image credit: Petr Kratochvil

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