When is Native…Invasive?

The Cup Plant in the Adirondacks:

In recent years, a new flower has appeared growing along the east branch of the Ausable River in the Adirondacks. It is a tall (8 to 10’) and beautiful member of the aster family and bees love it! The flower is known as Cup Plant or Indian Cup (Silphium perfoliatum) and is native to North America but not the Northeast. This plant originates in the tall grass prairie ecosystem of the mid-west where it coexists among other natives of that region. It also thrives along the fertile floodplains along the Ausable River where in the absence of its prairie cohorts it’s population is exploding and has gained the reputation of being an invasive plant as it chokes out the less competitive native plants. Its origins in the Adirondacks most likely date back twenty years where it became an escapee from a Keene garden, ensuing floods have spread it along the down stream river banks.

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Fall Mining Bee. Note the lack of pollen baskets. The female carries pollen on the upper part of her hing leg.

A plant is considered invasive when it aggressively outcompetes and overwhelms other plants in the area. In time, they often form a monoculture. Phragmites is known for outcompeting native cattails and other native aquatic vegetation. However, not all non-native plants are invasive, some plants such as dandelion and chicory have become naturalized.

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Honey Bees are non-native but not invasive. They work alongside other native bees.

The Cup Plant is so named for the large leaves that fuse together around the thick square stem forming a “cup”. This is one of the defining characteristics that separate it from woodland sunflowers (Helianthus spp.) and false sunflowers (Heliopsis spp.) other similar plants that grow along the river.

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The aster family is often called the daisy or sunflower family and flowers in this group consist of a disk of small flowers surrounded by ray flowers. The overall look is one flower head surrounded by petals. Look closer at the disk and you will see there are many tiny flowers clustered together. Bees and other pollinators love these flowers. Many flowers in this group bloom in the late summer and early fall.

Woodland Sunflower
Woodland Sunflower
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Another member of the Aster Family

 

The East Branch of the Ausable River
The East Branch of the Ausable River

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