By Claire Milsted
Almost all of our food comes directly or indirectly from flowering plants (angiosperms); many plants without conspicuous flowers, such as corn, fall into this category. Angiosperms release specialized cells known as pollen to carry half of their genetic information to other plants for reproduction (though many angiosperms also pollinate themselves). This Saturday’s Market Science session at Midtown Farmer’s Market focused on pollen and plant development. Even though the farmer’s market was unexpectedly rained out before 11am, many visitors were able to participate in one or more activities designed to trace plant development from a flower to pollen to seed.
In many species, this pollen must be carried by animal pollinators. About 35% of the global food supply comes from plants that require animal pollinators. Our first activity was a guessing game that asked visitors to guess how various flowering plants are pollinated. Most visitors knew about the importance of bees, but some were surprised to learn about other important vectors of pollination. For example, corn is wind-pollinated, while the Blue Agave Cactus is pollinated by the Mexican Long-nosed Bat.
Visitors were also offered the chance to examine various flowers both with the naked eye and with a dissection microscope. Visitors examined lilies and tomatoes, which have simple flowers with several pollen-containing anthers surrounding a pollen-receiving stigma. There were also compound flowers, with a single flower-head made of several small flowers. The compound flowers on display were chrysanthemums, the invasive species Queen Anne’s Lace, and daisies. Daisies are members of the Asteraceae family, which have flower heads that look like a single flower surrounded by petals, in fact each of the small bumps on the head are an individual disk flowers; the structures that look like petals are in fact ray flowers.
Visitors were also able to look at pollen from daylilies and tomatoes under a compound microscope. Daylily pollen was much larger and had a different shape. Finally, visitors were invited to dissect soaked beans and examine them under a dissection microscope. Volunteers explained the various components of a bean seed–its protective coat, two cotyledons which store energy for the growing plant, and a small embryo with two visible embryonic leaves (epicotyls). Hopefully these activities exploring flowers, pollinators, pollen, and seeds gave visitors a clearer view of the developmental and reproductive processes that play an important role in our gardens and on our farms.