Seen any good grass flowers lately?

Our summer is rushing along, as summers usually do. With the abundant rains this year, grasses are growing profusely and the grass flowers have been a treat to see. If you ask most people, they will say that grasses don’t have flowers. It all depends on what you consider a flower. The common notion is that a flower has to be colorful and showy. That’s fine if the flower is pollinated by an insect or other animal, but wind-pollinated flowers don’t bother with all that extravagant use of resources. Their flowers are the most basic models – tiny petals or none at all, no scents, no nectar. The wind doesn’t work any better with those things than it does without. All it takes to be a flower is a stamen or a carpel, and grass flowers have both – one to three stamens and a two-carpellate pistil usually.

Here are typical grass flowers. The anthers are yellow and the stigmas are feathery and white.

Here are typical grass flowers. The anthers are yellow and the stigmas are feathery and white.

I’ve been asked what grass flowers look like, and that’s a good question. Without a hand lens or other magnifier, it is hard to see them at all. Basically grass flowers form within a series of bracts – small modified leaves, which are usually green. This little package of flowers and bracts is called a spikelet. Each spikelet can have one to several flowers + bracts stacked together. When the flower is mature, a pair of little scales (the lodicule) at the base of the ovary swells and prys the stack of bracts apart. The stamens, typically three of them, dangle out on long, flexible filaments. The anthers are large compared to the size of the whole flower. They have to be to shed enough pollen. Wind tends to scatter pollen and dilute it. The stamens are the easiest part of the grass flower to see. The pistil typically has two styles and two feathery stigmas. If you would like more details on grass flowers see http://www.backyardnature.net/fl_grass.htm

The feathery stigmas have a large surface area to snag pollen. Their structure may also alter air flow, making it more turbulent and promoting pollen contact with the sticky stigmas. The stigmas are often white, but there are many colors in various grass species. After the grass flower has bloomed, the bracts close back up and there is little of the flower to see on the outside of the spikelet. Sometimes the stamens remain for a short while after the bracts close. Inside, the ovary of the flower is developing into a closed, dry fruit. The layers of the ovary wall adhere closely to the seed, so the whole thing is commonly called a seed or a grain. A kernal of wheat, for example, is technically a grass fruit.
This switchgrass has orange anthers and pink stigmas - pretty fancy for a grass.

This switchgrass has orange anthers and pink stigmas - pretty fancy for a grass.

The grass family is one of the largest of the flowering plant families, so my photos show only a tiny fraction of the variety of grass flowers. It’s another good challenge for field work – find the grass flowers. Happy hunting!

Many flowers in this grass inflorescence are blooming. 

Many flowers in this grass inflorescence are blooming.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: