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  Section: Introduction to Botany » Stems
 
 
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Stems

 
     
 
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Stems
  The Woody Dicot Stem
  The Herbaceous Dicot Stem
  The Monocot Stem

Stem tips, showing terminal buds of Aesculus, the horse chednut, and Magnolia tripetala The abundant leaf scars of Magnolia seem to confirm that the leaves are crowded into an umbrella-like circle
Figure 32-1 Stem tips, showing terminal buds
of Aesculus, the horse chednut, and Magnolia
tripetala. The abundant leaf scars of Magnolia
seem to confirm that the leaves are crowded
into an umbrella-like circle..
A stem may be defined as something that bears leaves. But this definition is too simplistic; it needs to be expanded so as to answer some pertinent questions. From where does a stem come? What part of the seed produces it? When one dissects a seed, it is found to bear a seed coat or two and, within the seed coat, an embryo. The embryo consists of cotyledons (the seed leaves, which are food sources), a radicle (which grows downward upon germination to produce the root), and a plumule (which grows upward to produce the stem and leaves). The cotyledons are attached to the plumule. The seedling thus has two parts: the epicotyl (that part above the cotyledons) and the hypocotyl (that part below the cotyledons). Thus, a stem can be defined as that part of a plant above the hypocotyl.

Gymnosperms are entirely woody, while both woody and herbaceous forms occur in angiosperms. Angiosperms include both monocots and dicots. These differences create a need for several descriptions of stem anatomy.

 
     
 
 
     



     
 
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