Yellow Fall Asters

When most folks consider a wildflower season, spring is usually what comes to mind, and rightfully so based on the sheer number of species that bloom then. But autumn also offers an impressive burst of color when some wildflowers make one last push to propagate before the killing frosts. Asters are particularly easy to find blooming now, especially yellow ones.

Asters belong to the largest group of flowering plants, the Composite (Compositae) family, also referred to as the Daisy family. A typical composite flower head has a central disk surrounded by a circle of petals that encircle the disk like windmill blades. The central disk is made up of many small flowers (that don’t look like flowers) grouped together, hence the name composite. The surrounding petals are called rays and vary in number from 10 to over 100.

There are more yellow fall flowering aster species that any other color and can be found blooming from late summer through November. They look a lot alike so identification can be daunting. But if you learn some key identification features, some can be picked out pretty easy. What follows are some descriptions of some more common species growing in our area.

Wingstem (Verbesina alternifolia): When you drive down the road and see an unmown field with tall yellow flowers, they are likely Wingstem with maybe some goldenrod. It often intermingles with the tall purple flowering Ironweed and together they put on quite a color show. Wingstem got its name from the four flat extensions (“wings”) that run along the stem. Each flower has only 2-8 unequal petals that reflex backwards from a spikey looking center disc.

Brown Eyed Susan (Rudbeckia triloba): This one is similar to its bigger sister Black Eyed Susan in having a dark central disc. But the Brown-eyed flower is smaller (1-2 inches wide) and has far fewer petals (only 8-12) that are notched on their ends. The stem below the flowers is usually dark and the lower leaves are commonly divided into three lobes.

Green Headed Coneflower (Rudbeckia laciniata): This one stands out by having a large protruding green central disk surrounded by 6-10 drooping petals. The leaves are divided into several lobes (finger-like extensions). This coneflower begins blooming in August and extends into September.

Jerusalem Artichoke (Helianthus tuberosus): This native wildflower is neither from Jerusalem nor an artichoke. It does produce an edible tuber with a flavor like an artichoke, so some say. This plant is huge, often over 10 feet tall, with large 2-3-inch-wide flowers that have 12-20 rays and a yellow center disc. The leaves are rough and sandpapery, and each has 3 main veins.

Besides providing a touch of fall color, asters are an important food source for insects, especially butterflies. They can be found in both field and forest, so a walk about anywhere will turn some up. Getting to know a few of them will make the walk more interesting.

By: Steve Roark
Volunteer Interpreter, Cumberland Gap National Historical Park.

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