13 September 2025

We’ve entered Seed Season in which late summer flowers set seed just in time for migrating sparrows and finches to eat them.

At top, wild bergamot’s (Monarda fistulosa) petals are gone and the central disc looks like a cluster of tiny pipes. American goldfinches have been busy pulling seeds out of them so the pipes may be empty by now.

Below, in Schenley Park I found pilewort a.k.a. American burnweed (Erechtites hieraciifolius) sporting both seeds and flowers. The flowers are tight green bundles with pistils and anthers protruding. The seeds are on filaments than float on the wind like dandelion fluff.

Pilewort is a native annual in the Aster family that loves disturbed soil and, according to Wikipedia, “is most abundant in areas that have been extensively disturbed, like where severe fire, timber harvest, or bulldozing has occurred.” This big clump of pilewort is growing in bulldozed debris.

At Sewickley Heights Park masses of bearded beggarticks (Bidens aristosa) glow in full bloom along the Pipeline Trail.

When they go to seed they’ll be annoying if you brush against them. Their seeds are the classic “hitchhikers” that latch easily onto your clothing.

7 September 2025

Some plants in Pittsburgh’s parks are feeling our moderate drought more than others. Here’s how a few of them have responded to the lack of rain.

Orange jewelweed (Impatiens capensis) is a native annual that grows in damp areas such as creek beds and ditches. The flower pictured at top has its roots in the creek bed of Phipps Run in Schenley Park where a stand of orange jewelweed looked healthy until the end of August. By the 28th this flower was shriveled and its leaves were turning yellow at the edges.

I know this because I took a photo of a nearby flower on 23 August (oval-shaped photo below). Six days before my photo it had rained 0.64 inches and the creek was flowing. By 28 August (photo at top) there had no rain for 11 days and the creek was dry.

By 31 August, there was still no rain and all the jewelweed looked pitiful.

Schenley Park’s false sunflowers (Heliopsis helianthoides) normally look healthy into early fall, even though they are always plagued by aphids. This year the blooms look beaten up. Have the aphids sucked out all their juices?

Otherplants are

Late boneset (Eupatorium serotinum) is a native perennial that’s not so picky about moisture so it’s flourishing in Schenley right now. It also does well because deer don’t eat it. Late boneset contains pyrrolizidine alkaloids.

Bittersweet nightshade (Solanum dulcamara), native to Eurasia and Africa, can grow in either dry or moist locations. This one managed to find enough water to set fruit. Wikipedia says its fruit is 84.1% water.

deertongue has sturdy thick leaves https://en.wikipedia.org/wiki/Dichanthelium_clandestinum

I used to think three-seeded mercury (Acalypha rhomboidea) was non-native because was so good at invading my garden. Instead it is native and versatile and is thriving right now at Schenley.

Some plants are coping with drought by luckily taking root on the mudflat at the mouth of Nine Mile Run at Duck Hollow. The native plant sneezeweed (Helenium autumnale) and the tropical South American plant purpletop vervain (Verbena bonariensis) set down roots along the Monongahela River after a flood deposited them there. They are are doing fine right now but if there’s another flood they’ll be swept away.

There’s no rain in the forecast so we’ll see more plant reactions to drought in the week to come.