Plant Diversity

Tracheophytes— Flowering Plants (Angiosperms)

What define the two major groups of angiosperms—monocots and dicots?

Angiosperms are classified into two major groups, monocots and dicots. The description of monocots and dicots is based on the first leaves that appear on the plant embryo: monocots have one seed leaf, while dicots have two seed leaves. Approximately 65,000 species of monocots and 175,000 species of dicots exist. Orchids, bamboo, palms, lilies, grains, and many grasses are examples of monocots. Dicots include most trees that are nonconiferous, shrubs, ornamental plants, and many food crops.

Several more differences exist between the two groups. The seed leaves, also called cotyledons, differ: monocots have one cotyledon, while dicots have two cotyledons. Other differences include the floral parts—monocots have them usually in threes, dicots usually in fours or fives; roots—monocots have fibrous roots, dicots have taproots; and vacular bundles in the plant’s stem—monocots are parallel, dicots are in a ring.


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