Botany

What are Dicotyledons



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The plant family of angiosperms (flowering plants) is divided into two major groups - the monocotyledons and the dicotyledons. Monocotyledons consist of the, grasses, palms, lilies and a few other plant groups whereas the dicotyledons are made up of almost every plant you can think of. They are the largest family. The name means - 'two seed leaves' because a dicotyledon seed has two tiny seed leaves hidden in the endosperm of the seed (monocotyledons have one).


Dicotyledons have several differences from other plants. Their vascular tissue - the phloem and xylem- is arranged in rings whereas in monocotyledons it is scattered in random paterns in the stem. The pollen of dicotyledons is pitted with pores whereas in other groups the pollen tends to be smooth and with only a single pore (or none).


The leaves of dicotyledons have divided or serrated edges and reticulate venation (a network of veins) whereas monotoctyledon leaves are strap-shapes and with entire margins and veins which are parallel.


Dicotyledon roots consist of a tap root which anchors the plant and numerous side roots whereas monocotyledons tend to have shallow root masses of small roots.


Dicotyledons have a tissue which is not present in monocotyledons and this is the cambium. Cambium is a meristematic (readily dividing) tissue which creates new phloem (food carrying tissue) on the outside and new xylem (water and nutrient carrying tissue) on the inside. Cambium runs in rings around the stem and is what gives trees their characteristic 'rings' as new cambium is created each year.


In evolutionary terms, dictoyledons are actually thought to be earlier than monoctoyledons, which is a surprises as they are more complex but it is to any organism's advantage if it gains the maximum benefits from the least adaptations and monocotyledons are thought to have done away with the complex tissues of the dicotyledons to become a separate group.


Dicotyledons are important because many of them form major parts of our food plants like fruit, berries, nuts and offer materials for use in building (trees) and are used to make many products.


It is difficult to answer the question ;what are dicotyledons?' without simply stating they are plants but they are a group of plants which is far more complex then the monocotyledons and as they form the majority of our useful plants, they are plants to be cherished, nurtured and protected.


Dicotyledons also have secondary thickening in their perenial forms - this is the laying down of lignin which allows stems to take on the 'woody' appearance of trees and shrubs. Monocotyledons, though many form tree-like structures like palms, never have the same strength as wood due to the internal cellular lay out.


Dictyledons - complex plants with less advanced evolution but still valued by us.

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