A subclass of the * Angiospermae containing all the flowering plants having embryos with one cotyledon. Its members only very rarely possess a cambium and hence lack secondary thickening although some families (e.g. Palmae) have arborescent forms. Other general features by which the Monocotyledonae can be distinguished from the * Dicotyledonae include: having narrow parallel-veined leaves; having flower parts inserted in threes, or multiples thereof; having a fibrous root system composed of adventitious roots; and having numerous scattered vascular bundles (see atactostele ). In some classifications monocotyledons are placed in the class Liliopsida. The 60 or so families of the monocotyledons have been divided into a various number of superorders (or subclasses) by different authorities. Two widely used modern classifications (those of A. Cronquist and of A. Takhtajan) both recognize four subclasses in the Liliopsida, the * Alismatidae , * Arecidae , * Commelinidae , and * Liliidae. |
