Wednesday, October 21, 2015

Autumn Meadow Plants Series: Part I - Shift from Common Milkweed to Dogbane

There has been a dramatic shift in the diversity of plants in the upper meadow this year. The Common Milkweed population has plummeted from over 1000 plants to just around 50 and it has been replaced by another milky sapped plant, Dogbane (Apocynum cannabinum). (See Blog entry: July 7, 2014 for earlier story)

The meadow went from looking like this:

to this, in just over a year: 

There is greater diversity, than just 2 years ago, including many hardwood tree saplings including Sweetgum and Black Cherry, numerous grasses and the following plants:

Canada Goldenrod (Solidago canadenis)
Pokeweed (Phytolacca americana)
Yellow Toadflax (Linaria vulgarius)
Black-eyed Susan (Rudbeckia hirta)
Common Ironweed (Vernonia fasciculata)
Wild Carrot (Daucus carota)
Common Yarrow (Achillea millefolium)
White Heath Aster (Symphyotrichum ericoides)
Canada Thistle (Cirsium arvense)

In this entry, the focus is on the expansion of Dogbane, what it is and its role for pollinators. 

Dogbane or also known as Indian Hemp, grows 2 - 5' tall, is smooth, red-stemmed, which are filled with a milky, latex sap that is bitter tasting and highly toxic. It prefers full sun and wet soil and spreads aggressively from underground rhizomes. 

In early summer, it produces a grouping of small fragrant white flowers which are an excellent nectar source for many pollinators, including many different types of bees, butterflies, skippers, fritillaries and is a host to many larvae of various moths.(See:

Historically, this plant's silky fibers were used by the Lenni Lenape and other Native Americans to make robe, netting and baskets. In the fall, long seed pods hang in clusters and pop open as they dry, to expose seeds, which are attached to white silky threads to help them float long distances. 

Common Milkweed and Dogbane are often mistaken for one another due to similar leaf shape and plant size and shape and flower clusters. Because it contains a milky, poisonous sap as Common Milkweed and serves as a host to many other pollinator larvae, I wondered if it was also a host plant for Monarchs? 

It is NOT, according to Robert Dirig of Cornell, who confirmed that Monarch definitely do not use it as a host plant. (See:

The question remains of why Dogbane out competed Common Milkweed. They both have deep aggressively spreading rhizomes and prefer disturbed ground, sun and wet conditions, which are all present in this meadow. Perhaps, Milkweed has encountered a disease or a pest 
(see: t There were no reported disease issues with Dogbane, that I could find. Perhaps, it was the combination of increased Goldenrod and Dogbane populations that have pushed out the Milkweed?

The upper meadow will be mowed November 1 this year. It will be interesting to see the changes in the coming year. 

Check back for the continuation of this series: Autumn Meadow Plants Series: Part II: Newcomers: Ironweed and Asters.

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