Herbal Sleuths

"Before planting an outdoor herb garden, I had my second, third, and fourth graders choose projects on different uses of herbs," says Perryville, MO, teacher Sharon Hayden. She first suggested several broad project areas such as investigating herbs that were used in healing or exploring culinary uses of herbs in other countries. Small student groups then chose one broad topic or herb and generated questions they'd like to investigate more thoroughly.

"As students planned and conducted their investigations, they sought information from a range of resources," notes Sharon. "These included pharmacists and nurses, the Internet, families, and books." One group wanted to examine whether homegrown aloe or commercial burn creams would more effectively soothe burns. When another teacher burned herself on a stove, the team went into action. "When I questioned them about how they would accurately assess the effectiveness of different treatments," describes Sharon, "they realized that they had to develop a process for describing and judging the treatments' impacts." This prompted students to create a visual rating system, using a descriptive scale from one to five, then rating the affected area each day.

One group wondered whether catnip is really more tantalizing to cats than other herbs (thyme and oregano, for instance). They designed and created toys, then stuffed some of them with catnip and some with the other herbs they'd grown. "Although we didn't have time for a 'fair test,' one student plans to test these with her cat during the summer, documenting its reactions to each toy," explains Sharon.

Another group identified the herbs and spices in recipes from a number of countries, then looked for patterns in recipes coming from different regions. "By growing herbs and experimenting with their myriad uses," concludes Sharon, "students developed a deeper understanding of what herbs are, beyond the stuff that Mom shakes from bottles."

Herb or Spice?

When botanists use the term herbaceous, they mean a plant that is soft stemmed, with little woody tissue. But in culinary and other ethnobotanical uses, herbs are usually defined as plants of temperate climates whose leaves are harvested for use. It can get confusing: Although most are nonwoody, some woody plants like rosemary, whose leaves we use, are herbs in a culinary sense.

Invite students to rub the leaves of aromatic herbs to break microscopic oil glands and release their fragrance. Then ask students to imagine why these plants might have evolved with these distinct aromas and flavors. (Botanists believe that they are largely a defense against being eaten by herbivores.) Ask students to brainstorm common herbs in which we eat both the leaves and the seeds (e.g., dill).

Spices, on the other hand, are mainly tropical plants in which we typically use the roots (ginger), fruits (vanilla pods), flowers (cloves), seeds (pepper), or bark (cinnamon).

Consider having students identify the tropics of Cancer and Capricorn, which roughly separate tropical and temperate zones, and compare climate factors in both zones. Invite them to brainstorm which popular flavoring is neither an herb nor a spice. (Salt is a mineral not derived from a plant!)

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