Swamp Milkweed in Montgomery Co., Maryland (7/8/2018). Photo by Robert Ferraro. (MBP list)

Swamp Milkweed in Talbot Co., Maryland (7/28/2013). Photo by Jared Satchell. (MBP list)

Swamp Milkweed blooming in Montgomery Co., Maryland (6/5/2012). Photo by Fritz Flohr Reynolds. (MBP list)

Swamp Milkweed in Worcester Co., Maryland (7/22/2011). Photo by Bill Hubick. (MBP list)

Swamp Milkweed in Queen Anne's Co., Maryland (7/5/2016). Photo by Wayne Longbottom. (MBP list)

Swamp Milkweed blooming in Charles Co., Maryland (8/22/2015). Photo by Jim Stasz. (MBP list)

Swamp Milkweed in Howard Co., Maryland (8/12/2017). Photo by Ashley Bradford. (MBP list)

Swamp Milkweed seed pods in Garrett Co., Maryland (9/13/2013). Photo by Jim Stasz. (MBP list)

Swamp Milkweed blooming in Cecil Co., Maryland (7/21/2013). Photo by Sean McCandless. (MBP list)

Swamp Milkweed seed pods in Howard Co., Maryland (8/12/2015). Photo by Joanne Solem. (MBP list)

Swamp Milkweed with seed pods in Charles Co., Maryland (9/23/2014). Photo by Jim Brighton. (MBP list)

The seeds of Swamp Milkweed in Howard Co., Maryland (9/26/2013). Photo by Bonnie Ott. (MBP list)

Swamp Milkweed blooming in Anne Arundel Co., Maryland (8/3/2016). Photo by Robert Ferraro. (MBP list)

Swamp Milkweed in Talbot Co., Maryland (9/21/2017). Photo by Wayne Longbottom. (MBP list)

Blooming Swamp Milkweed hosting a Great Purple Hairstreak in Talbot Co., Maryland (12/1/2017). Photo by Dana Menke. (MBP list)

Swamp Milkweed hosting a Small Milkweed Beetle and unidentified weevil in Howard Co., Maryland (6/23/2015). Photo by Jim Wilkinson. (MBP list)