Tuesday, June 15, 2010

Black-eyed Susan

Black-eyed Susan, Rudbeckia hirta, is a common plant that is recognized by many. It grows in a wide variety of disturbed habitats and can produce blooms on the poorest of sites. So, if I’m working to increase populations of rare plants, why would I be so interested in this common flower.

Black-eyed Susan grows as either an annual or a biennial. Early season seeds usually produce clusters of basal leaves that survive the winter and grow to produce the earliest blooms. Late season seeds wait and germinate in early spring and normally produce late season flowers. The challenge facing plants that must annually produce new populations from seed is having suitable unoccupied ground in which to grow. Clumps of Black-eyed Susan show up in different areas each year. Learning the dispersal mechanisms employed by common plants will help me to understand the possible ways that rare plants move through the landscape.

The plant dies after producing seed, so it’s important for that seed to be spread out into suitable growing sites. The long flower stalk is quite strong and limber and can stand erect long after death. The stalk sways in the wind or is bounced back and forth by birds and allows the seeds to fall or be thrown several feet from the plant. Why then do these populations die out so quickly and how do new populations develop far from other plants?

In order for the plant to successfully develop, the seed must fall in a place that is not already full of other plants. Bare ground is typically a temporary situation. Plants soon fill any void and make it more difficult for new plants to develop from seed. So the populations of these short lived plants are constantly jumping around the landscape. Strangely, many people won’t understand what these plants are doing, because they are used to seeing extravagant populations of Black-eyed Susans growing in areas of mass disturbance and don’t notice when the flowers are no longer there.

Of course, there are insects benefiting from this plant. That little katydid looks much like the one I saw yesterday on the New Jersey Tea. Possibly it’s just a younger version.


  1. Lovely images. I've enjoyed these little flowers all my life, but never knew so much about them. I continue to learn more every time I visit.

  2. So thats what happens to them then!! There has been over the years Blackeyed Susans then none then some and etc. on my property !! You learn something new everyday!!! Thanks for the info!!

  3. Thanks, Lois. I used to pick these flowers every summer in my Grandparent's fields.

    grammie g - Today I drove past a run-down hay field that was almost solid Black-eyed Susan. A beautiful site for travelers, but probably not for the farmer.