In the Weeds - Alien Invaders

Rock Creek Park is home to many wonderful flora and fauna. Sadly, it is also home to a number of alien invaders. A few of these have crept into our garden.  Here are the invasive exotic plants that I have found in the Mamie D. Lee Community Garden, one of two community gardens in the park.

One hot spot for alien invaders is the fence adjacent to the Mamie D. Lee School. Clearing this fence was the project for a special work day. Ana Chuquin, a ranger from the US National Park Service, came out to help us identify invasive weeds growing along the fence. She showed us the difference between native and exotic vines - we have both growing.  Natives include poison ivy and trumpet creeper - whereas porcelain berry, pictured below, is the exotic invasive.  She also told us about the Rock Creek Park weed warrior program that trains volunteers in invasive weed species. This training, which she teaches, is 5 hours, half in the classroom, half in the field.  Once trained, weed warriors are asked adopt a piece of parkland - such as our fence or meadow - for a year.  The next weed warrior training session is September 16 and 19, 2015.  Please click on the link to register.

Porcelain berry vine with berries

The fence is covered with porcelain berry, which looks a little bit like a grape vine, except that the berries, which start green, turn a bright turquoise/blue color. This vine can take over an area.  The fence line is also home to some Japanese bush honeysuckle. Both spread readily by berries, eaten by birds and other wildlife. Remove the flowers and berries and you limit the spread.

Young shoot of  porcelain berry 

Porcelain berry pops up all over the garden, but it can be pulled as it emerges. The young shoots have a reddish brown tinge,  I find it growing near the hose bib in my plot.  This vine should not be neglected for long or it will cover anything and everything nearby.  

Porcelain berry wine with flower and green berries

 Japanese bush honeysuckle has lovely flowers that look just like honeysuckle vines but are not as fragrant.  The plant is a bush, with pinnate leaves.  The berries are a beautiful bright red; sadly, they are not nutritious for wildlife. I've heard them called "junk food" for birds.  This weed should be cut back and pulled. If you catch it before bloom, it can be composted. The blooms and berries should be bagged and discarded in the trash.

Japanese bush honeysuckle in bloom  

Japanese bush honeysuckle with berries

I've also see n mile-a-minute vine growing near that fence, but not this year.  This weed is a minute is a prickly green vine with triangular leaves that grows a mile a minute, hence its name.  This needs to be hand pulled as soon as it emerges.  The larger it gets, the pricklier it gets, and the harder it is to pull. Like porcelain berry, it also has turquoise blue berries.  This should be pulled as soon as it is soon.  If it is blooming, or has berries, it should be bagged and discarded in the trash.    

English ivy climbing tree along the fence

Another alien invader along the fence is English ivy.  This often escapes from yards and gardens.  It may be deliberately dumped in parkland by unscrupulous fly-by-night landscapers who want to dispose of it quickly and easily. The ivy takes root, climbs trees, and eventually kills them. It also destroys native habitat. Any English ivy in our garden should be pulled, bagged, and discarded in the trash. This weed should not be composted - it roots too easily.

Star of Bethlehem 

Scattered throughout the garden is a seasonal perennial weed that flowers in the spring - Star of Bethlehem.  I pulled lots of  this out of my plot this year - it has long and narrow green leaves, with a white stripe down the center, similar to a crocus - with green and white flowers blooming in later spring.  It is a late spring flowering bulb that goes dormant after flowering. These bulbs should be dug out, bagged, and discarded in the trash.

A few of our gardeners grow shiso, or Perilla, as an annual herb. This is a reddish Asian herb that is grown in many gardens - unfortunately it also escapes to the wild.  It looks like purple ruffled basil but with larger leaves and a very mild herbal fragrance. This can become invasive if allowed to go to seed.

Perilla, also known as Shiso  

There is a large healthy patch of Japanese Knotweed growing across the footpath from the garden. This is an incredibly invasive shrub that can take over an entire natural area, outcompeting native plants.  They say, however, that you can eat its shoots in the early spring.

Wineberry leaves and fuzzy stem

Wineberries grow along the Gallatin Street parking lot and footpath, at the edge of the woods to the south of the garden. These are my favorite alien invader - the berries are really tasty.  Wineberries are briar bushes, like raspberries, with small reddish fuzzy spines all over the stems.  The berries ripen in June, to become food for foragers - like me- and wildlife. I not-so-secretly hope that the Park Service is too busy to clear these.

Tree of Heaven Seedling

Last, but far from least, we have Tree of Heaven growing in the woods outside the garden, near the tool shed and compost. This is a dreadful invasive - when you cut down one tree, it sprouts shoots from the stump, like a hydra. It can form small thickets. I've heard forestry managers call it the "tree from hell," for this reason.  Tree of Heaven also reproduces by seed - I've pulled a few seedlings from the area near the compost, and suggest that you do the same. The National Park Service will be treating the parent trees with herbicide sometime this fall or winter.  

As I conclude this post, I'd like to share the National Park Service Publication on invasive weeds of the mid Atlantic.  It's a great reference book that I'm always giving away.  Learn to identify alien invaders, and remover them by any means necessary, even if that means you must ear them.  

http://www.nps.gov/plants/alien/pubs/midatlantic/midatlantic.pdf
  
Happy gardening!

Christina