You Grow Girl™

Binomial nomenclature is useful because you don't have to know what every species looks like to have a common botanical language. In my first plant taxonomy class, we learned to identify families by a gut feeling (or "gestalt" as my prof called it). Once you can look at a plant and know its family, it is pretty easy to use a key to figure out the genus and species. Thus, knowing families is actually more useful than memorizing every plant's two part name. Many families have common characteristics such as flower petal arrangement (for example, a solitary flower with six petals not fused is typical of the Liliaceae or lily family) or reproductive organ arrangement (for example, four stamens, two tall and two short, is characteristic of the Brassicaceae or mustard family). For many common plants, you can know the genus by casual observation. For example: the genus Lupinus, or lupine (Fabaceae or pea family) can be apparent from the pea-type flowers arranged in a cone-like inflorescence and its distinctive leaves, but identification at the species level will take more investigation into the details of floral morphology. Some genera are more difficult to key to species than others and maybe it's not even important which kind of lupine you've got. If someone tells you about a plant they have and you've never heard of the species, you can get a pretty good idea of what the plant looks like if the genus is familiar to you, even if the particular species isn't. You do this all the time and may not even know it. Begonia is a plant genus name.

Why Not Use Common Names?

Common names can be easy to remember and, when talking to folks from your own region, useful. But if you just know a plant as `butter and eggs', it can lead to miscommunication because there are lots of flowering plants with yellow and white petals known as `butter and eggs'. `Butter and eggs' could be of the genus Ranunculus (family: Ranunculaceae or buttercup) or the genus Dendromecon (family: Papaveraceae or poppy). If you know which genus or even which family the plant belongs to, this knowledge can help you find the plant in a nursery or talk about it with other people. Common names can be more informative than `butter and eggs' and still cause problems. For example, cactus is the common name for any plant with succulent leaves and spines. But plants have evolved this characteristic several times throughout history and there are several plant families with cactus plants within them. In Africa, cacti are commonly found in the Euphorbiaceae family - a family that also contains spurges and Poinsettia whose ovaries are above the flower petals. In South America, cacti are found in the Cactaceae family - a family that only includes succulents and whose ovaries are below the flower petals. While cactus is a useful term in describing appearance and growth habit, it is not useful in describing flower structure.