13 September 2021

Today’s article began with a question asked three times: What is that weed? I couldn’t remember the name even though I knew each was in the knotweed family (Polygonaceae) and that a similar native species was named for Pennsylvania.

On the first question I took a picture in Schenley Park, above. On the second question, Claire Bauerle took a picture at Duff Park, below. My plant and Claire’s plant are both alien but not the same species.

Claire’s plant shows its name on its leaves, a shadowy thumbprint in the center of the leaf.

Lady’s thumb (Persicaria maculosa) is a Eurasian smartweed that first appeared in the Great Lakes region in 1843, has spread across the continent, and is sometimes invasive. The dark thumbprint is a simple way to identify the plant.

My plant is similar but lacks the thumbprint. Not the same species but my photo is not detailed enough for a complete identification. My guess is Oriental lady’s thumb (Persicaria longiseta) a common weed in Asian rice paddies introduced to North America near Philadelphia in 1910 and now found across eastern North America.

The third question was answered on Sunday’s Botanical Society walk on the South Side where we found the smartweed named for Pennsylvania.

Pinkweed or Pennsylvania smartweed (Persicaria pensylvanica) now grows in waste places around the world. Gangly-looking compared to the lady’s thumbs, it has longer stalks, thinner leaves, and fatter, shorter, paler flower heads.

Here’s a single stalk.

It has no flower bristles like those found on Oriental lady’s thumb P. maculata.

All three smartweeds have stems that connect to the stalks at knot-like ochreas. Two of them, P. longiseta and P. pensylvanicum have bristly ochreas, shown below.

Identifying smartweeds is much trickier than I’ve described so I may have misidentified the first two plants.

If I was smart I’d know what to look for and take better pictures to key them out.

(photos by Kate St. John and Claire Bauerle)

p.s. Three range maps which might not work in Chrome: P. maculosa, P. longiseta, P. pensylvanica

31 July 2021

In late July field flowers bloom while others develop seeds.

The photo at top of oxeye or false sunflowers (Heliopsis helianthoides) was supposed to be a documentation photo so I could study the leaves. Can you find the milkweed bug on one of the flowers?

Blue vervain (Verbena hastata) is blooming at Presque Isle State Park where I took this photo on Wednesday. Vervain flowers are so small that the plant looks boring from afar. It is well worth a closer look.

On Thursday Charity Kheshgi and I explored the grassland top of the slag heap at Nine Mile Run. In one area the slag is so porous that rainwater percolates straight though it, creating a desert habitat. Nonetheless we found a vibrant orange butterfly weed (Asclepias tuberosa) in bloom.

Namesake plant: Dwarf St. John’s wort (Hypericum mutilum) is native to North America.

Seeds! Redbud trees (Cercis canadensis) in the city parks have a bumper crop of seed pods this year.

Nodding thistle (Carduus nutans) has gone to seed along the lower Nine Mile Run Trail where it looked like this in June (click here). We saw many American goldfinches feeding on these natural thistle feeders.

Today is our last chance to enjoy July. The weather is lovely in Pittsburgh so get outdoors.

(photos by Kate St. John)

10 July 2021

Pittsburgh’s weather fluctuated this week from pleasant to oppressively humid. Always late to get outdoors, I missed the best part of each day. The flowers were open but the birds were hiding at:

• Duck Hollow and Lower Nine Mile Run on 3 July. 73 degrees, a pleasant day!
• Montour Trail on 5 July. 85 degrees in the shade, cooler in Enlow Tunnel.
• Three Rivers Heritage Trail on the South Side on 6 July. Almost 90 degrees and very sunny.

I was dripping with sweat on 6 July when I found this namesake plant, St. John’s wort (Hypericum prolificum), pushing up from a crack in the sidewalk. What a hardy plant standing tall on a hot day. I wilted after 30 minutes in the sun.

p.s. A story about peppergrass.

(photos by Kate St. John)

12 June 2021

Temperatures have fluctuated widely in the past couple of weeks — from chilly damp to searing heat — but the plants and insects keep on their steady march to summer.

Above, yellow goat’s beard (Tragopogon dubius) now has both flowers and seeds.

Below, this sprig of bedstraw (Galium sp) has almost finished blooming with just one flower and many seeds. The plant feels sticky because its stems, leaves, and seed pods are all covered in tiny hooked bristles that act like Velcro.

In Schenley Park the tulip trees (Liriodendron tulipifera) have finished blooming, the “tulips” are fading and dropping their petals.

As birdsong wanes the bugs are taking over the soundscape. I’ve already heard the first crickets and an unknown-to-me insect that buzzes at 5,000 hertz in Schenley Park.

And who is this? None of us could name him yesterday at Moraine State Park. Can you identify this hunched insect with bright orange antenna tips? If so, please leave a comment.

UPDATE: This insect is a leaf-footed bug, probably Acanthocephalus terminalis, thanks to Kim’s comment.

(photos by Kate St. John)

30 May 2021

In Pennsylvania we plant azaleas and rhododendrons in our gardens but we can also find them in the wild. I am reminded of this in late May when the cultivated rhododendrons and wild azaleas bloom.

At the garden store azalea bushes are short dense shrubs that bloom in April, while rhododendrons are tall woody shrubs that bloom in late May. Scientifically they are all Rhododendrons with minor differences. The big difference for me is that the garden plants bloom four to six weeks before the wild ones.

Yesterday I found flowering rhododendrons on Pitt’s campus. Some were white (below) like their wild progenitors shown at top in Fayette County.

Others were hybridized to create purple flowers.

To see the wild ones I visit the Laurel Highlands around the Fourth of July, especially Ferncliff Peninsula at Ohiopyle State Park. Nowadays it pays to go a little earlier than the Fourth because climate change has moved things up.

Meanwhile last weekend at Moraine State Park Karyn Delaney found wild azalea in bloom.

Sometimes wild azaleas (Rhododenron periclymenoides) are called “pinkster” in southwestern Pennsylvania but it’s not because the flower is pink. They were named “pinxter” for the Dutch word for Pentecost because wild azaleas bloom at that time of year.

This year Pentecost was 23 May. Wild azalea is blooming right on time.

(photos by Kate St. John and Karyn Delaney)

p.s. What’s the difference between an azalea and a rhododendron? Not much. They have slightly different leaves and azalea flowers usually have 5 stamens while other rhododendrons have 10.