Plant science for plant people.

A confession before the science: this issue is a day late. I spent the weekend in a weedy field of my own with my hands in the dirt, and I forgot to come back and hit send. There's something fitting about that, given the week is mostly about milkweed and the 2,095 people who stopped to photograph it. Thanks for waiting. Here's the week.

Two thousand people photographed the same plant this week. Common milkweed is in peak bloom, and the flood of observations is building a real-time map of where monarchs can feed, because milkweed is the only plant their caterpillars will eat.

That's 2,095 sightings in seven days, with butterfly milkweed adding another 1,100. Together they trace where monarchs travel, one sighting at a time. If you've planted milkweed along a fence line or let it volunteer in a sunny corner, your patch is on the map.

Milkweed keeps the door open for monarchs, but for other pollinators, doors are closing. Drought-stressed cucumber plants attract more bees by producing extra flowers, yet still fail to set fruit; the plant is too exhausted to follow through. In sprayed apple orchards, the few remaining bees crowd onto whatever blooms during peak toxicity, a trap that quietly eliminates specialist visitors. The unsprayed cemeteries next door still hum with diversity.

Sometimes the most useful thing you can do is let a weed bloom and take a picture of it.