Problem : Draw a monocot and a dicot stem, being sure to emphasize the differences in the arrangement of vascular tissue.

Figure %: Monocot and Dicot Stems

Problem : How does the vascular system in monocots expand when the plant grows?

As a monocot grows in size, discrete new vascular bundles are produced that are scattered throughout the new tissue.

Problem : How does the vascular system in dicots expand when the plant grows?

As a dicot grows, existing vascular bundles grow larger. The vascular cambium in between the xylem and phloem produces new xylem and phloem cells, pushing the old cells outward and expanding the size of the bundle.

Problem : What are herbaceous dicots? Woody dicots?

Herbaceous dicots (mostly annuals) have soft, non-woody stems. Woody dicots (mostly perennials, including most trees) have woody stems.

Problem : Describe the features of a woody dicot's vascular system.

In mature woody dicots, the vascular bundles (composed of xylem, phloem, and vascular cambium) join together to form continuous rings around the interior of the stem. Woody dicots also develop a lateral system of nutrient transport in which vessels called rays extend horizontally from the phloem to the pith, carrying nutrients to the pith for storage or to the phloem for dispersal.