- Evolution in the Plant Kingdom. Illustrate your essay with...
Evolution in the Plant Kingdom. Illustrate your essay with specific examples.
There are four major groups of modern land plant:
non-vascular land plants that include mosses , liverworts and
hornworts; seedless vascular plants including ferns and horsetails;
gymnosperms including conifers and cycads that are characterised by
the protection conferred upon the embryo by a hardened seed casing;
and angiosperms such that protect and disperse their seeds by
flowering or fruiting, reviewed by (Raven et al., 2005), (Mader,
The evolution of modern land plants from
unicellular prokaryotes that acquired the ability to
photosynthesise will be discussed here. The evidence in favour of
modern land plants sharing a relatively recent common ancestor with
algae will also be presented. Additionally, the sequence of
evolutionary divergences that have produced modern land plants from
their prokaryotic ancestors will be discussed and the adaptations
that modern plant groups have evolved in order to successfully
exist on land will also be described.
In terms of the success of land plant groups, each
group must be well adapted to the environment that it inhabits in
order to survive the evolutionary process. In terms of species
diversity, angiosperms of the phylum Anthrophyta contain around
250,000 species compared to around 25,000 species of bryophytes
(that include the non vascular mosses, liverworts and hornworts)
reviewed by (Raven et al., 2005), but in terms of the number of
different environmental conditions they inhabit, the non-vascular
plants could be described as being the most successful plant group
and due to their adaptations in temperature resistance and in
maximising small volumes of water, reviewed by (Mader, 2007).
Lichens are known to survive extreme desiccation and inhabit a wide
range of conditions on Earth, including arctic, boreal and desert
environments, reviewed by DePriest, (2004).
Modern land plants have evolved over billions of
years from a unicellular prokaryotic ancestor that underwent
endosymbiosis with cyanobacteria and gained the ability to
photosynthesise. Divergence from freshwater green algae and
movement onto land was followed by the evolution of early land
plants into the four modern groups that exist today. Each group of
modern land-plants possesses evolutionary adaptations appropriate
to the environmental conditions in which they inhabit and each can
be described as successful within its own environment.