The Primary Plant Body
The vegetative body of higher plants is in general made up of two organ systems, the root system and the shoot system. The shoot system is further composed of two organs, the stem and the leaf. Stems may be composed entirely of primary tissues (tissues derived directly from the primary meristematic tissues of the shoot tip), or they may be composed of primary tissues and secondary tissues (tissues derived directly from the lateral meristems). Usually, stems composed of primary tissues have only a limited number of hard, dense cells present and are spoken of as herbaceous structures. In contrast, stems made up largely of secondary tissues usually have a considerable number of hard, dense cells and are spoken of as woody structures. The herbaceous, dicotyledonous stem will be used as the first example in the following discussion of the primary plant body.
Unable to display preview. Download preview PDF.