Archive for the 'Plants' Category

Oct 28 2013

Tick City!

Published by under Plants

Japanese barberry, Moraine State Park, 20 Oct 2013 (photo by Kate St. John)

I remember these little red fruits from my childhood.  I used to pick the berries along my walk to elementary school and roll them between my fingers.  Firm, shiny, and somehow soothing.

Japanese barberry (Berberis thunbergii) is a pretty plant which forms a thorny border that discourages kids and dogs from entering one’s yard.  For this and other reasons it was introduced to the U.S. in 1875.  Unfortunately by now Berberis thunbergii and its European cousin (Berberis vulgaris) have overtaken our native barberry (Berberis canadensis) and become invasive.

Japanese barberry has a secret advantage over Pennsylvania’s native plants. Deer won’t eat it so it easily forms dense, thorny thickets.  But don’t plant it!  It’s a tick magnet.

Studies by the Connecticut Agricultural Experiment Station in Lyme, Connecticut discovered a strong link between dense Japanese barberry thickets and Lyme disease.  Deer ticks prefer these thickets for their cool, moist microclimate.  White-footed mice hang out in the thickets because the larger predators can’t reach them there.  White-footed mice are the main carriers of Lyme disease bacteria.  The ticks bite the mice and voilà!  Lots of Lyme disease.

The Adirondack Daily Enterprise wrote of this study: “Deer ticks are 67 percent more likely to be in areas infested with barberry than those areas that have native plants, and a higher percentage of ticks in infested areas carry the Lyme bacteria than those in areas that are barberry-free – 126 infected ticks per acre versus 10 per acre. When managers removed barberry plants, the number of ticks dropped up to 80 percent – a compelling outcome.”

So if you want to find deer ticks and Lyme disease, bushwhack through a barberry thicket.

The plant in this photograph was alone, growing by the side of a rail trail, but I found a tick on my pants after I took the photo.

Tick City!

(photo by Kate St. John)

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Oct 21 2013

Eats Poison Ivy

Published by under Bird Behavior,Plants

Yellow-rumped warbler eating poison ivy berries (photo by Cris Hamilton)

How many of us get a rash from poison ivy?  (Raise your hands.)

It looks like the vast majority of us are allergic to it while some are not sure.

I know only one person who’s immune to poison ivy.  The rest of us get a rash, mild to severe, or avoid the plant so carefully that we haven’t tested the limits recently.

Birds are not only immune to poison ivy’s itchy oils — they eat its berries.

Here, a migrating yellow-rumped warbler (Setophaga coronata) inspects a cluster of poison ivy berries, and then he swallows one.

Yellow-rumped warbler about to swallow a poison ivy berry (photo by Cris Hamilton)

It makes my throat itch to think about it.


(photos by Cris Hamilton)

p.s. Notice this warbler’s wide field of vision.  In the first photo you can see both of his eyes from the top of his head.

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Oct 12 2013

Slightly Aggravating

Published by under Plants

Agrimony seeds, focus stack (Museum of Toulouse via Wikimedia Commons)

Take a walk outdoors at this time of year and you’re likely to come home with some of these stuck to your clothing.

These tiny burs are the seed pods of agrimony (Agrimonia eupatoria), a plant native to Europe that was brought to North America for its herbal properties. (See Mark’s comment! This species doesn’t occur locally but we have similar natives.)

Though the burs look wicked in this close up, they’re actually small and rather weak. Compared to burdock they’re only slightly aggravating.

Click here for a view of a local species (Agrimonia parviflora) when it’s flowering — photos I took at Jennings Prairie last year.


(photo produced using focus stacking, Museum of Toulose, from Wikimedia Commons. Click on the image to see the original)

4 responses so far

Oct 05 2013


Published by under Plants,Schenley Park

Beggar Ticks (photo by Kate St. John)

Related to Spanish needles, most of the Beggar Ticks (Bidens frondosa) in Schenley Park have not yet gone to seed.

When they do they will stick tight to my clothing.  It happens every year.

Click here to see the seeds.

(photo by Kate St. John)

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Sep 30 2013

Invasion Of A Thousand Leaves

Published by under Plants

Eurasian watermilfoil (photo by Charlie Hickey)

What are these spiky flowers Charlie Hickey found peeking out of a lake near his home?

Charlie identified them as Eurasian Water-milfoil (Myriophyllum spicatum) an invasive aquatic weed with soft, feathery, submerged leaves that form thick mats in North American lakes. Click on the photo and scroll down to read his description of it.

When I looked further I was amazed to learn that…

  • Eurasian Water-milfoil can propagate from a small piece of stem so a little bit caught in the boat propeller in one lake can be carried to another lake and spawn a new invasion.  I saw signs in Maine warning people to clean their boats after they take them out of the water.
  • North America has its own native water-milfoil called Northern Water-milfoil (Myriophyllum sibiricum).  The two species can be identified by their leaves but they hybridize and the hybrid inherits characteristics of both.  Very hard to identify.
  • The invader is hard to get rid of.  Many techniques have been tried including imported biological controls using a moth, a weevil and a fish.  The fish didn’t work out so well.  It prefers to eat native plants so it denuded the lakes and left the Eurasian water-milfoil for last.
  • In the Adirondacks and New England divers remove it by hand every year.  This technique is so successful that according to Wikipedia:  “After only three years of hand harvesting in Saranac Lake the program was able to reduce the amount harvested from over 18 tons to just 800 pounds per year.”

How did water-milfoil get its name?  My guess is that “milfoil” is a contraction of the French “mille feuille” which means “thousands of leaves.”

When it overruns a lake it looks like an invasion of a thousand — no, a million — leaves.

(photo by Charlie Hickey. Click on the image to see the original)

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Sep 29 2013

Why It’s Here

Published by under Plants

This month Japanese knotweed (Polygonum cuspidatum or Fallopia japonica) is showing off another reason why gardeners imported it.

The flowers have become delicate white seed pods perched above the symmetrical leaves.

Too bad it’s invasive.


(photo by Kate St. John)

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Sep 21 2013

Spanish Needles

Published by under Plants

Spanish needles in bloom (photo by Kate St. John)

These small yellow flowers look innocent, but after they’re fertilized the central disk grows longer and develops into hard, brown seeds.


The seeds splay out as they dry. Each one is topped by a tiny pitchfork of two to four spikes with downward-facing barbs.

Sanish needles gone to seed (photo by Kate St. John)

The needle-like seeds detach easily from the plant…


… and stick to my sweater.

Spanish needles on my sweater (photo by Kate St. John)

That’s when I noticed the plant.


The Spanish Needles plant (Bidens bipinnata) is so annoying I was sure it was an alien invasive.  Not!  It’s a native annual that’s very adaptable, willing to grow in disturbed soil in vacant lots.  These seeds grabbed me on Winthrop Street in Oakland.

Bidens bipinnata has many hitchhiker relatives in the Bidens genus.  I identified this one by its lobed leaves and needle-like seeds.


(photos by Kate St. John)

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Sep 17 2013

Cucumbers: Wild And Bur

Published by under Plants

Wild Cucumber (photo by Dianne Machesney)

Pumpkins, zucchini, yellow squash, gourds, the members of the Cucurbitaceae family are ripe and ready to eat in North America.

In Pennsylvania’s moist thickets you’ll also find wild and bur cucumbers … but don’t eat them!

Wild cucumber (Echinocystis lobata) is an annual vine that can be unruly at this time of year. After a summer of growing, climbing and blooming it has thrown its tendrils around trees and over bushes.  Its spiny cucumber fruits hang at intervals along the vine waiting to dry out and explode the seeds in all directions.

The seeds take up a big part of the fruit as you can see from this sliced one.   I wonder if any animals eat this…
Wild cucumber, opened (photo by Dianne Machesney)


A look-alike plant with even smaller, spikier fruits is the Bur cucumber (Sicyos angulatus).  Its clustered “cucumbers” aren’t edible and frankly look dangerous because the ratio of spines to fruit is a lot higher.
Bur Cucumber (photo by Dianne Machesney)

Newcomb’s Wildflower Guide separates these plants by their flower parts but there are other hints as well:

  • Wild cucumber has six petals, Bur has five.
  • Wild has smooth stems. Bur has sticky hairs on its stem.
  • Wild has deeply lobed leaves. Bur has broad, heart-shaped leaves.
  • Wild’s fruits hang separately. Bur’s fruits are in clusters.
  • Wild’s fruits are about the size of the leaves (can be 2″). Bur’s fruits are small.

Dianne and Bob Machesney found the wild ones at the Butler-Freeport Trail and burs at Green Cove in Washington County.

If you want to eat a cucumber, go for the real thing in the garden or grocery store.  It’s been cultivated for 3,000 years.


(photos by Dianne Machesney)

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Sep 15 2013

Lettuce or Rattlesnake

Published by under Plants

Tall White Lettuce, from the top (photo by Kate St. John)

Though I know this plant grows in western Pennsylvania and have seen its mysterious leaves in Spring, the only place I’ve seen it produce this many flowers is in Maine.

Tall White Lettuce (Prenanthes altissima) is sometimes called Tall Rattlesnakeroot.  It has such variable leaves and flowers that Newcomb’s Wildflower Guide keys it out with both five and six repeating parts.

The one distinguishing feature is drooping greenish flowers whose stamens hang below the petals.  I can’t think of any other plant that looks like this.

flowers_tallwhitelettuce_maine2012_1398b_kmsTall White Lettuce flowers (photo by Kate St. John)

Descriptions of Tall White Lettuce say it tastes bitter, so why is it called “”lettuce”?

Better yet, why “rattlesnake root”?


(photos by Kate St. John)

3 responses so far

Sep 14 2013

Where Are The White Petals?

Published by under Plants

Gardeners in Maine have told me this flower is a real pain.  It’s a perennial that’s hard to get rid of if it’s in your yard.

Originally from Eurasia, Tansy (Tanacetum vulgare) looks like a daisy without any white petals.  It was brought to North America as a medicinal herb but it grows too well in Maine’s coastal climate.

I often see it by the side of the road and wonder … where are the white petals?

(photo by Pauline Eccles via Wikimedia Commons)

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