Tuesday, August 21, 2018

Traits of the Most Obliging Plants

The nicest plants in the garden are first and foremost, of course, free.

Preferably they have been given to you by a lovely and generous friend, so that every time you see your plants you can be reminded of them.  Such is the case with my beautiful dahlias.

Amiable plants also pop up in the garden even though you never bought them.  Perhaps they came as a freebie with another plant you bought and you never really even noticed it until it surprised you with delicate yellow blooms one day, such as this Yellow Corydalis in the shade garden. 

Nice and polite plants also faithfully bloom all summer even with complete neglect from the gardener.  This Threadleaf Coreopsis that grows next to the driveway has slowly expanded every year and seems to always be in bloom.  I don't even remember ever cleaning up dead foliage after winter (though I'm sure I do?)

Of course the best plants come back every year after winter - even if they are not rated hardy for your zone.  My 'Priscilla' Gladiolas shocked me with their return after a harsh winter.  Looking online, it seems this variety is among the hardiest of the showy gladiolas.  I hope it keeps coming back. That would be quite nice and obliging of it.

The most polite plants also keep popping up in the garden even after a gardener is sure that she has killed it.  Good to see you again, Viola walteri 'Silver Gem'.

A really obliging plant produces both food and beautiful flowers.  Of course, if the plant was truly obliging, those flowers would be fragrant...  Check, check, and check for the Chinese Red Noodle Bean!

flowers of the Chinese Red Noodle Bean
Other amiable plants put on such a show every year that visitors are in awe of the fact that the gardener managed to grow such large flowers.  (Shhh, don't tell them that 'Cranberry Crush' Hibiscus naturally makes those giant flowers, no matter what I do to it...)

Not all plants have such showy flowers. A well-mannered plant works whatever blooms it has with gusto for the pollinators.  This Liatris ligulistylis might have blooms that are straight out of a Dr. Seuss book, but it is completely irresistible to Monarch Butterflies.

The best plants of all realize that their gardener planted them in the wrong spot and MOVE THEMSELVES over a couple feet to a better one (and one where the gardener was struggling to grow other things).  I swear I did not plant this Great Blue Lobelia there.

So many lovely and obliging plants in my garden!  Now if only one of my plants would be nice to enough catch and eat some of those pesky bugs outside...

Ah, thank you dear Pitcher Plant!  That's very considerate of you!

Do you have any particularly obliging plants in your garden?

Friday, August 10, 2018

Biological Control of Purple Loosestrife

It's the height of summer, and the Purple Loosestrife in my detention pond is in full bloom.

However, when I say full bloom, I mean FULL bloom.  For here in North America, Purple Loosestrife, aka Lythrum salicaria, is a highly invasive plant.

Just some of the Purple Loosestrife in my detention pond
There's no denying that this particular invasive is a strikingly gorgeous plant.  Hailing from Europe and Asia, this wetland plant has been prized throughout history as an ornamental in the garden in addition to its medicinal use for gastrointestinal ailments.

Overseas, there are a number of cultivars of Purple Loosestrife.  'Blush', which has pale pink flowers and 'Feuerkerzeze', which has sterile, vividly-colored double flowers, have both won the British Royal Horticultural Society's Award of Garden Merit.

Hummingbird Clearwing Moth on Purple Loosestrife
In the 1800's Purple Loosestrife was introduced into North America either accidentally as seeds floating in ship ballast water or intentionally as an ornamental.  In the years that followed bee keepers spread it to other parts of North America, as its many flowers offered an abundance of nectar for the bees.  It has since spread into most US states and up into Canada.

While bees and other pollinators love the flowers, unfortunately there are not many animals or insects here that eat the plant to keep it in check.  Purple Loosestrife invades wetlands, crowding out native plants.  It forms dense, impenetrable stands that are unsuitable for native wildlife such as ducks, frogs and turtles, and these animals are often forced to relocate. 

Once Purple Loosestrife is established in an area, it is nearly impossible to get rid of due to the immense number of seeds each plant produces.  A mature plant can produce millions of seeds, and these seeds remain viable in the soil for years.  It can also re-sprout from any pieces of roots left in the soil or water.  Managing this invasive plant by manual removal, burning, cutting, herbicides, and water management have all been tried... and found to be either too difficult, too costly, or environmentally unsuitable. 

So what to do about this plant?  In the mid 1980's, biologists began to search for what is usually the last resort - a biological control.  Biological controls are very tricky, as we have found out over the years.  Deliberately introducing something new into the environment can go terribly wrong.  Asian ladybugs that were released to fight aphids have now edged out many of our native ladybugs.  Our largest native moth, the Cecropia silk moth, is now under attack from a parasitic fly that was meant to control gypsy moths.  And most of us know what happened with Kudzu, aka 'the vine that ate the South'...

Thankfully, testing for a biological agent is now much more rigorous.  Scientists considered over 100 insects overseas that were known to feed on Purple Loosestrife.  Several were thought to have possibility, and extensive testing began in Europe.  The insects were exposed to many North American species of plants to make sure that they would not end also attacking our native plants if introduced here.  In 1992, after six years of testing, the US Department of Agriculture approved four insects for release into the US for the control of Loosestrife:  two leaf-eating beetles (Galerucella calmariensis and Galerucella pusilla), one flower-feeding weevil (Nanophyes marmoratus), and one root-boring weevil (Hylobius transversovittatus).

Hylobius transversovittatus on Purple Loosestrife
(photo via wikipedia)
Would these biological controls work?  In the mid 1990's the U.S. Fish and Wildlife Service began releasing the leaf-eating beetles in various suitable areas, including two National Wildlife Refuges here in Massachusetts.  Between 2000 and 2008 the state government teamed up with various wetland conservations programs to release more beetles in Massachusetts through the Purple Loosestrife Biocontrol Project.  Beetles were released at 43 sites throughout the state, starting with Turner's Pond in Walpole, just a few towns away from me.  Within four years, Turner's Pond saw an 80% drop in Loosestrife plants.  This biological control worked!

However, to be a true success, the release of the beetles should not cause any negative effects on the environment.  Studies have found that the beetles do sometimes feed on two similar native plants; however they prefer Purple Loosestrife, and no serious problems have been reported.  Monitoring will continue, but so far this is one biological control that is a success!

Now I just need some of those beetles to fly over to my detention pond...

With all this Purple Loosestrife, I have quite a good meal for them!

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