19 August 2015

If you ever see this plant, eradicate it!

My first encounter with Mile-a-minute weed was a decade ago in the Laurel Highlands when a small patch of leaves caught my eye.  Such perfect triangles! I didn’t know the plant but if I had I would have uprooted it.

Mile-a-minute weed (Persicaria perfoliata) is an annual, trailing vine, that thrives in sunlight and can grow 6 inches a day(!).  It has triangular leaves and perfoliate cups at the stem joints, called ocreae, where it produces flowers and fruit.  Notice the recurved thorns on the stems and on the underside of the leaf veins that give it this alternate name: Devil’s tear-thumb.

Persicaria perfoliata tried to invade North America several times but didn’t take hold until the late 1930s when it charmed a nurseryman in York County, Pennsylvania. He received it unintentionally in a shipment of seeds, was fascinated and allowed it to grow. By the time he realized his mistake it was too late.  Birds and animals love the fruit and spread the plant. 

Mile-a-minute now swamps southern Pennsylvania, Maryland, and parts of the Mid-Atlantic and New England.  It has spread more than 300 miles since it left York.  Click here for the map.

If you think you’ve found Mile-a-minute weed, check a few things before you pull.  Does it have perfect-triangle leaves?  Does it have perfoliate cups at the stem joints? Does it have thorns?  If so, you’ve found the bad stuff. 

Before you put on long pants, long sleeves and gloves to pull it out there’s one more question to ask: Does it have fruit? If so, be very careful not to spread the seeds while you pull — collect them first. This annual plant can only return next year if the seeds spread.

I found a fruitless specimen dying in Frick Park last weekend.  I had noticed it in July and was finally returning to pull it but, thankfully, park stewards had already dosed the area with therapeutic defoliant.  Good!  I administered the final blow and pulled it out.

(photos by Kate St. John and Wikimedia Commons)

These yellow capsules are closed but soon they’ll burst open and fling their pollen to the wind.

Last Wednesday I found this giant ragweed (Ambrosia trifida) growing along Nine Mile Run Trail south of Commercial Street.  The plant is so tall that the flower spike is at eye — or should I say nose — level.  Fortunately it’s not as tall as the record-setting 21-foot specimen in Texas.

Though the flowers aren’t open yet ragweed season officially begins today, August 15.  Hang on to your handkerchiefs!

Learn more here about ragweed and how to identify the ‘common’ one.

(photos by Kate St. John)

UPDATE August 16:  The capsules have opened.  The pollen is out.   Ahhhh-choo!

Green-headed coneflower (Rudbeckia laciniata) is blooming now in western Pennsylvania.

Look for its green head and swept-back yellow petals in open woods and fields.

(photo by Kate St. John)

This night-blooming flower grows like a weed in Arizona.  Here, Donna Memon captured a trumpet glowing in the setting sun.

Datura grows easily in the Arizona desert and is cultivated around the world.  There are currently nine species, many of which are hard to identify because the plant changes its characteristics to suit the growing conditions.  Its common names include jimsonweed, moonflower and angel’s trumpets.

Though beautiful it is extremely poisonous, producing hallucinations, elevated body temperature, tachycardia, severe pupil dilation, unconsciousness and death.  Thus it was surprising to me that it’s called “sacred datura” in Arizona because Navajo and Havasupai shamans used low doses for religious hallucinations.

The proper dose is hard to determine and if you get it wrong you die.  The correct amount varies — even in the same plant — based on age, soil conditions and local weather.  Despite the warnings people try it and, as Wikipedia says, “Few substances have received as many severely negative recreational experience reports as has Datura. The overwhelming majority of those who describe their use of Datura find their experiences extremely unpleasant both mentally and often physically dangerous.”

The angel’s trumpet is beautiful but a deadly way to see angels.

Read more here at Wikipedia.

(photos by Donna Memon)

This flower is blooming everywhere right now but we never notice it.  Its beauty is tiny and the plant is a weed so we pass it by.

Galinsoga or Quickweed is an annual in the Aster family with small daisy-like flowers with five notched petals.  The leaves are opposite and toothed in a jumbled mass below the long, branching flower stems that give the plant a messy “leggy” appearance, 6-18 inches high.

Look closely and you’ll see the leaves and stems are both hairy.  But no one looks closely unless they want to eat it (yes it’s edible).

Here’s what we typically see when walk past Galinsoga on the street.

Once you start looking, Quickweed is everywhere: growing in the sidewalk cracks, sprouting in gardens, covering an abandoned lot where its density makes it pretty.  Local gardeners call it “Pittsburgh Pest.”

It earned the name Quickweed or Raceweed because it produces seed rapidly (7,500 seeds per plant per year) and has many generations in the same season.

When it’s gone to seed it looks like this.

The genus is Galinsoga but what is the species?

Good question!  My Newcomb’s Wildflower Guide lists only Galinsoga ciliata = Galinsoga quadriradiata.  Richard Nugent and Flora Pittsburghensis both identify it as Galinsoga parviflora.  Quadriradiata is from Mexico, parviflora is from South America.  In any case, it didn’t jump an ocean to find us.

But it jumped an ocean to Europe.  Galinsoga parviflora was taken from Peru to Kew Gardens in 1796 where it escaped to the wild and quickly became a weed.

Aha!  Quickweed.

(photos by Kate St.John)

11 July 2015

Here are some pink flowers you don’t see every day.

Indian pipe (Monotropa uniflora) is a parasite in a three-way relationship. It’s lives on a symbiotic fungus that gets its own food from tree roots in exchange for mineral nutrients.

Since Indian pipe doesn’t need chlorophyll the plant is ghostly white and can live in the deep shade of a dense forest.  When Indian pipe blooms the flowers droop downward.

But as soon as they’re fertilized the flowers move into the heads up position.  Esther Allen taught us that this helps the plant disperse its seeds.

Most plants have erect flowers that nod when fertilized.  Indian pipe is backwards in many ways.

Learn more about Indian pipe in this article from the Arkansas Native Plant Society.

(heads up photo by Kate St. John. Heads down photo from Wikimedia Commons; click on the photo to see the original)