This week I planted a flat of Butterfly Milkweed seeds and put them outdoors to chill for a month or so. They’ll sprout when the weather gets serious about spring. From this small effort, I look forward to loads of colorful flowers in my native wildflower garden.
My accomplishment, planting the seeds, was the easy part. By contrast, what the flowers achieved is amazing.
Milkweeds make copious nectar, which entices insects to come and pollinate the flowers. A milkweed succeeds only if a bee, butterfly, or other insect pulls pollen out of one flower and deposits it inside another. The second flower must be the same species but cannot be on the same plant. Milkweed requires Another.
A milkweed plant conceals its pollen down inside the flowers. While a bee or butterfly is busy slurping nectar, a foot sometime accidentally slides down into an inconspicuous slit in the blossom. (Accidentally from the point of view of the insect, that is. As for the milkweed, the “accident” serves a function.)
The slit is a trap.
The insect struggles to yank free. Out of sight, the wiggling leg snags pollen sacs, which will still hang on when the insect gets its leg loose. If you closely watch bees foraging on milkweeds, you’ll probably find one with yellowish sacs of pollen, called pollinia, stuck to its legs.
Sometimes you’ll see one who is dragging several pollinia attached to each leg. And that bee is now working for the milkweed.
OK, that was the first stage of milkweed pollination.
For the second stage, the insect must have the same accident happen again, with the same foot, in an appropriate flower. Much can go wrong.
If the insect goes next to a different species, there is no pollination.
If it visits another flower on the same plant, there is no pollination.
If it doesn’t happen to get that foot caught again, there is no pollination.
But if the pollen comes off the leg in the right spot in the right flower, pollination will succeed. The flower will develop a pod full of seeds. A new generation of milkweeds is on its way.
Some milkweed species are not common. It may be farther to the next plant than the insect is likely to fly. No pollination.
I marvel that milkweeds ever get pollinated at all.
Butterfly Milkweed is one of the most popular native flowers for gardens. It makes a splash of color in summer that attracts hummingbirds as well as insects.
However, even though hummingbirds feed on the nectar of milkweeds, the birds don’t pollinate them. A hummingbird’s tiny feet are still far too big to slip down into a milkweed’s blossom and pick up pollen packets.
Butterflies, bees, and other insects are just the right size for the job. My garden appreciates their work. Look close. Can you spot the Monarch butterfly caterpillar?
It’s feasting too.
How thrilling! I have just a tiny, tiny patch of sun. I'm encouraged to plant a few milkweed plants there this year.
Now I know why my Butterfly Milkweed plant from last Spring died - I had only one plant. This year I will try again, better informed!