Every flowering plant arranges its blossoms in a consistent, characteristic way. Noticing how a plant's blossoms are arranged can be very helpful when we are trying to identify the plant. But before looking at the different kinds of flower arrangements, we need to become introduced to a good word. Here it is:
An inflorescence is a flowering plant's cluster of flowers. Below, with the pink splatters representing flowers, or blossoms, are diagrams of various common inflorescence types.
Now let's look at the inflorescences of some real plants. To make the situation like "real life" I take a ten-minute walk and gather what I find, place what I collect onto my scanner screen, and below you see the results.
At the far left, that's a little Oxalis plant with a single yellow blossom rising above its clover-like leaves. Usually healthy examples of this species of Oxalis bear their flowers in umbels, but this little plant was right along my path and did well to produce a single flower. I'm glad to begin with this ambiguous situation because it reminds us that sometimes plants can be tricky. If this little Oxalis had been healthy enough to produce several flowers, they'd have been arranged in an umbel.
The second-from-the-left is a "head" of White Clover, Trifolium repens. This inflorescence type isn't shown on our diagram. The white head consists of dozens of slender, white flowers, the pedicels (flower stems) of which all join at one place so that the flowers form a sort of sphere. You would call this inflorescence type a globose head, "globose" just meaning spherical, like a globe.
The third-from-the-left is part of an inflorescence of the Lyre-leaved Sage, Salvia lyrata. Here only the top two flowers remain. Below these flowers the corollas have fallen off after pollination, leaving only the calyxes surrounding the maturing fruits. You can see that the flowers and calyxes attach to the main stem directly, without possessing any pedicle (flower stem), so this inflorescence type is a spike. If the flowers had pedicles, as shown at the right, the inflorescence would be a raceme. The picture at the right shows a raceme of green, immature Poke fruits (Phytolacca americana).
The second-from-the-right plant is Spring Vetch, Vicia sativa. This plant typically produces two flowers at each node, one flower above each of the opposite leaves. You would say that it has paired flowers. Again, this flower type isn't shown in our diagram and again it shows that just because you have a nice diagram with fancy terms, Mother Nature is often more diverse than we expect her to be...
On the far right, that's False Garlic, Nothoscordum bivalve, with its blossoms in a classic umbel. Well, sometimes these plants do exactly what you want them to...
Sometimes inflorescences are plum mind boggling. For instance, at the right you see the flowering structure of the big-leafed garden plant called Elephant's Ear. The Elephant's Ear belongs to the Arum Family, in which we also find such plants as Jack-in-the-pulpit, Philodendron, Anthurium, Caladium, and other mostly tropical plants.
In the the picture, male and female flowers grow separated from one another on a slender, fingerlike item surrounded by a cylinder of leaflike material. I've cut away one side of the leafy cylinder. On the fingerlike thing inside the cylinder, the green bumps at the bottom are hundreds of female flowers. At the top you see hundreds of cream-colored male flowers. The male and female flowers are separated by many sterile objects called staminodes.
The fingerlike thing bearing the flowers and staminodes is called a spadix and the leafy material forming a cylinder around the spadix is called a spathe. Gardeners who don't understand flower anatomy too well are likely to call the spathe the plant's "flower," but we know that actually in the picture at the right we're seeing hundreds of flowers.