24 August 2024

This week I encountered giant ragweed (Ambrosia trifida) along the trail at Hays Woods. Though the plant I photographed was still shorter than me it typically reaches six feet tall. The flower spikes are loaded with male pollen flowers, facing downward to dangle in the wind and spread the pollen that makes many people sneeze.

Pollen season has been wicked this year. Today is Day 9 of ragweed which officially started on 15 August. However, thanks to climate change, allergies are starting earlier and lasting longer nowadays.

If you suffer from ragweed allergies your nose knows when it started blooming but you might not know what common ragweed (Ambrosia artemisiifolia) looks like. What is making you miserable? Check out this vintage article.

21 August 2024

When I took this photo at Hays Woods yesterday, I knew the plant’s name — biennial gaura — but just for fun I asked PictureThis to identify it. It said “Biennial Gaura, a species of Evening Primrose.” Evening Primrose was a surprise. I didn’t think they were related.

Common evening primrose (Oenothera biennis) has four evenly spaced petals with stamens and pistil in the middle. Though the flower appears to be open here, it actually opens more widely in the evening.

Biennial gaura (Oenothera gaura) also has four petals but they are all on one side of the stem with stamens and pistil drooping below. The shape of the flower looks “irregular” to me and “evening” doesn’t seem to apply either. The flower looks like it stays open all day.

However, studies of the former genus Gaura caused all of it to be absorbed into Oenothera (Evening Primrose ) in 2007. The reason I was surprised 17 years later is that my hardback copy of Newcomb’s Wildflower Guide was published in 1997. I should rely more on apps these days.

Here are additional photos of both flowers for further comparison.

Both plants are “weedy” species so they’re pretty easy to find in the field. Look for common evening primrose in sunny or mostly sunny places, often along trails. Biennial gaura wants full sun and dry, rocky soil. At Hays Woods it grows at the powerline cut.

Note that biennial gaura flowers are much smaller than evening primrose. Tiny but beautiful.

27 July 2024

At yesterday’s annual Wissahickon Nature Club outing at Jennings Prairie we found many familiar plants in the expected places, but some that should be at peak in late July were already past their prime, probably due to this year’s heat. We found some other surprises as well.

We usually have to search with binoculars to find a lesser purple fringed orchid (Platanthera psycodes) nestled in the distance but yesterday we saw this one near the trail.

Hairy willowherb (Epilobium hirsutum) was exactly where we expected it in the valley under the footbridge, but we also found some in the woods.

Jumpseed (Persicaria virginiana) flowers are usually white but these were pink as well.

Jack-in-the-pulpit fruit is still green. It won’t turn red until next month.

Here’s a two-step lesson on how halberd-leaf tearthumb (Persicaria arifolia) got its common name.

10 June 2024

Between the glory of woodland spring ephemerals and summer’s splash of native field flowers, June has fewer blooming natives. On a walk yesterday along the Three Rivers Heritage Trail near Millvale I found a host of pretty flowers, many of them invasive.

Orange day-lily (Hemerocallis fulva) is native to Asia and well established in Pennsylvania. You’ll see it blooming in ditches, along railroad tracks and in gardens. It pops up in so many places that it has at least 10 common names. Orange day-lily is considered invasive in Pennsylvania because its tubers create thick clumps that crowd out native plants in sensitive habitats.

Japanese knotweed (Reynoutria japonica) is listed as one of the world’s worst invasive species. Right now its flowers have just opened in southwestern PA. By the end of summer the flowers will be in long, sweet-smelling racemes, a favorite of bees and butterflies.

Crown vetch (Securigera varia), native to Eurasia and Africa, is in now full bloom. Read about its invasive qualities here.

What’s that popcorn-like smell? It’s poison hemlock (Conium maculatum) and it’s in bloom. You won’t want this plant anywhere you find it. Here’s how to get rid of it; expect a multi-year effort.)

(all photos by Kate St. John)