 One
of most important characteristic of plants is that they undergo
photosynthesis which is that
they use the
energy of the sun to convert water and carbon dioxide into food (sugars)
and oxygen by means of chlorophyll
and carotenoid
pigments; it stores food in the
form of starch.
A plant has cellulose
cell walls; it lacks centrioles, which
are structures involved in cell division in animals. It usually cannot
move of its own accord. The ancestors of modern plants evolved in the
seas nearly 700 million years ago. Another 265 million years passed
before the first plants appeared on land. Possibly exist nearly 300,000
different species of plants.
Containing the
• Bryophytes (small plant lacking vascular tissue and lacking true
roots,
stems, and leaves)
• Mosses (small plants forming green carpets consisting of a stem like-axis with small leaf-like),
• Liverworts (grow close to the ground with lobed which resemble lobes
of liver)
• Seedless Vascular Plants (lycopods,
horsetails, and ferns)
• Seed Producers including
Gymnosperms which have no
flowers (conifers, cycads, ginkgos,
and Welwitschias) and Angiospermae
the flowering plants in which the seeds are enclosed in a
fruit that develops from the
ovary of the flower.
Angiosperms are
divided into two subclasses:
Dicotyledonae (with two seed leaves (cotyledons)
and branched leaf
vein)
Monocotyledonae. (with one
seed leaf and parallel leaf veins)
Plants grows almost everywhere on Earth from the tundra to the
rainforest, in the desert and in the water the only places without
plants are the polar and high altitude land, the really arid deserts,
and the deep ocean. ■ |
