A few days later, I stumbled across another perplexing milkweed mystery. A Florida gardener sent me a mystery milkweed photo wondering was this showy milkweed…or perhaps the plantabulous purple milkweed variety?
Over the 4th of July, I saw these same plants on a city boulevard in Chicago. After seeing them up close and personal, I was pretty sure they weren’t a perennial milkweed species I was familiar with…but I left the windy city without making a positive ID.
Now, I’ve discovered a familiar ‘swampostor’ blending in with our swamp milkweed patch. But this time the faux milkweed made a fatal mistake. The cascading flowers clearly revealed its family secret…milkweed is not the father!
Before I saw its flowers, I was wondering if this mystery plant could be the result of cross-pollination between swamp/tropical milkweed. After the blooms were revealed, I realized there was a milkweed impostor in our midst…
Milkweed Impostor 2
This July, a second milkweed impostor has been discovered in the swamp milkweed patch. It also has leaves resembling Asclepias incarnata, but its flowing purple panicles have revealed it as a milkweed brother from another mother:
This season I turned to a new ally in my question for plant identification:
A helpful group member had my answer within a matter of minutes:
Lythrum salicaria (purple loosestrife)
After further research I discovered this plant is classified as a noxious weed in our state, so I dug it out and put it in the yard waste can.
Another milkweed mystery solved…
Milkweed Impostor 3
When comparing plants that look like milkweed, dogbane probably fools the most people into thinking they’ve found the common milkweed jackpot, but dogbane is not a viable option for hungry monarch caterpillars to feed on.
Ironically, another milkweed caterpillar, the tussock moth caterpillar is able to grow through its life cycle eating dogbane leaves…go figure!
So what is the difference between milkweed and dogbane?
Asclepias syriaca grows from a single green stem, while dogbane grows on multiple, often-reddish stems:
Common Milkweed typically blooms earlier in the season and has showier blooms:
In August and September, common milkweed plants are easy to distinguish with fat seed pods, while dogbane pods are long and slender.
Both milkweed and dogbane contain milky sap so don’t try to ID that way!
If you know other plants that look like a species of milkweed and how to tell the difference, post in the comment section below…
Click the following link to find 30 REAL Milkweed Varieties for monarch butterflies and your butterfly garden.