Dogbane (also known as Indian Hemp), officially Apocynum cannabinum, is another of the whites blooming with enthusiasm now in what seems to be, if observed from a distance, a sea of green at Pin Oak Marsh.
Its various names are descriptive. "Dog" plus "bane" (poison) tells us that it will upset the digestive tract of anything that eats it. Apocynum means "poisonous to dogs."
The other half of the name, "cannabinum," means "like hemp." Native Americans reportedly used the bark of dogbane stems, collected in the fall when plants were mature but still living, then dried, to make cord and/or rope.
"Cannabinum" might suggest recreational drug to some, but it would not be at all advisable to dry and attempt to smoke it.
Dogbane also frequently is mistaken to be a variety of milkweed, but it is not that at all --- despite the fact that if you cut it, the sap will be milky and white; it "looks" vaguely milkweedish; and its long, slender seedpods behave much the same as those of stouter milkweeds do.
Monarch butterflies, sorely in need of Midwest milkweed in these herbicide-plagued times, will not touch it. So, while pretty, it's probably not a plant for the butterfly garden.
It's another of those pretty poisons --- lovely to look at, unwise to ingest.