Monocotyledonous plants, commonly referred to as monocots, are a group of flowering plants that have only one embryonic leaf, or cotyledon, in their seeds. They are one of the two major groups into which the flowering plants have traditionally been divided, the other being dicotyledonous plants, or dicots. Some characteristics of monocots include:
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Vascular tissue: Monocots have a distinctive arrangement of vascular tissue known as an atactostele in which the vascular tissue is scattered rather than arranged in concentric rings.
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Collenchyma: Collenchyma is absent in monocot stems, roots, and leaves.
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Secondary growth: Many monocots are herbaceous and do not have the ability to increase the width of a stem (secondary growth) via the same kind of vascular cambium found in non-monocot woody plants. However, some monocots do have secondary growth.
There are approximately 60,000 species of monocots, including the most economically important of all plant families, Poaceae (true grasses), and the largest of all plant families, Orchidaceae (orchids). Other prominent monocot families include Liliaceae (lilies), Arecaceae (palms), and Iridaceae (irises).
