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Embryo Development-1 |
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 Polarity:
The word Polar implies things which are at the opposite ends of an
axis. The North Pole and the South
Pole are at the opposite ends of an Axis drawn through
the center of the Earth. We could have East and West Poles if we wanted them. However,
these would be harder to define. Most plants are polar. The root and shoot are typically the "poles" we visualize when we think about plants. We can also visualize the Shoot Tip and the Shoot Base as opposite ends of the shoot axis. The same applies to roots, and other organs which are polar. We can even see polarity with Marchantia and other "Bryophytes". However, the Gametophytes of Anthoceros have Orbicular growth and it is harder to see their polarity. Coleochaete (Chlorophyta) have a similar growth form and produce discus-like organisms. Macroalgae typically have Polar Growth. However, Volvox which is spherical is apolar.
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