Lecture Enrichment Ideas - Chapter 9

9.1. The Flowering Plant

Show a series of non-native flowering plants; ask students to determine if they are monocot or dicot; select some slides with leaf features, others with flowers or stem features only.

9.2. Plant Tissues and Cells

When a tree is cut in winter, the tree stump in spring often bubbles with sap. What cells are involved and what does this indicate about the living tissues of this organism compared to an animal, etc.?

9.3. Organization of Roots

Consider that you could develop a strain of plants that produced root hairs throughout the root area, greatly increasing the surface area! Why would root hairs not be an advantage in the zone of elongation?

9.4. Organization of Stems

Rural students will recognize that a wire fastened to a tree many years ago does not move upward but is merely embedded at the same height. Ask for a correct scientific explanation of why this occurs.

When a valuable yard tree is damaged, why does the specialist coat the open wood with tar? Why not just leave it exposed? Why does an initial damage to a tree soon lead to severe insect infestation?

When a fence post of unknown age is discovered, it is often possible to determine its date by matching it with tree rings from logs of known age. How can they do this? Would this be possible in a region where climate (growing seasons) were uniform year-after-year?

9.5. Organization of Leaves

Considering when sap moves up and down in trees for storage; ask why maple syrup runs in late winter and early spring. When would be the best time to cut timber so that the tree trunks would not be loaded with sap that would cause them to warp badly? Why do many indoor plant leaves actually "polish" up when rubbed with a cloth?

9.6. Modified Roots, Stems, and Leaves

Either bring in a variety of vegetables or show slides of grocery produce and query which part is being eaten as food. The properties of stems and roots were also deeply involved in human history: hard sod required the invention of a better plow to allow cultivation of the prairie "breadbasket"; log cabins and modern frame houses rely on lignin and other structural molecules; fibers and leaves are still a major source of housing, rope and container material--virtually any slide of native peoples or pictures from National Geographic magazine will reveal heavy human dependence on these plant structures.

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