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Re: Purple Loosestrife (Lythrum)

Harry Dewey <harryd@CapAccess.org> wrote:

> Dear Liane: I have been growing lythrum in suburban Washington DC for 
> about 30 years.  I've ordinary sandy loam, and, as long as I 
> don't plant it in the shade, it thrives.  It is NOT invasive.  A 
> clump actually increases far less than most perennials.  In the shade, it 
> languishes, and dies.
> 
> A neighbor of mine has, for several years, been upset that 
> lythrum is taking over ponds along Interstate Highway 95 (and elsewhere) all 
> the way from Maryland to Maine.  Apparently it IS invasive when 
> planted in water, or in bogs that are constantly wet.  Her group 
> has persuaded nursery owners in this vicinity to stop selling 
> lythrum.
> 
> I know many gardens in this area where lythrum is beautiful and 
> well-behaved.  The only time I've ever seen it ramp was in a pond 
> on the east side of the highway between Princeton and New 
> Brunswick, New Jersey, about a mile or so north of Princeton.  
> That was many years ago.  It was in full bloom, and had taken 
> over the whole south end of the pond.  It is still one of the 
> most beautiful sights I've ever seen.  If I'd been the owner of 
> the pond, I might have been upset.
> 
> My neighbor says the wind can blow the seeds onto distant stream 
> banks.  I bike every day from my house down to the Beltsville 
> Park, down Howard Road, past numerous specimen plants of lythrum 
> (generally one per garden), and then for a mile along the Paint 
> Branch, as it's called.  No seeds have blown down to the stream 
> bed in the thirty years I've lived here.  Well, I mean they 
> haven't taken root.
> 
> It's a wonderful plant, and if you haven't a bog, enjoy it!

I was going to remain silent on this thread but this has 
motivated me to speak up.  You may not see any Lythrum growing 
in your stream bed, but take a look around all the wetlands in a 
50 mile radius.  I know the Beltsville area of Maryland rather 
well and I can assure you that there are wetlands in peril in 
your vicinity from Lythrum taking over.   This is simply 
incorrect information about this plant.

Rather than paraphrase, I am including a Gardens-L post written 
by Kay Lancaster a couple of months ago on the subject.

===============================================

The "garden hybrids" of purple loosestrife that were thought to
be sterile are actually fertile, especially when crossed with
the parent L. salicaria.  The seeds are tiny, and blow for miles,
so even though you think you're far from wetlands, you're probably
not far enough... 50 miles has been documented.

It's a beautiful plant, true, but it can totally take over a wetlands in
less than 10 years, destroying most of the ability of the wetland to
filter runoff and detoxify it.  The plant is native to Europe and Asia
where it's kept in check by various diseases and insects we don't have in
North America.  I've seen it in Wicken Fen in England, and it's a pale
shadow of itself compared to an established population here.  (Hey,
dandelions are even well behaved in their native countries).  The plant is
not eaten by local animals or insects, nor used as nesting or habitat...
it's sort of the plant equivalent of acres of blacktop as far as the
wildlife is concerned.

There are a lot of plants that can be substituted for it in gardening
situations.  Filipendula rubra, Queen of the Prairie, looks very much like
it from a distance, is a native species, grows easily, and can be a real
traffic stopper (4-7 ft), as is its relative, meadowsweet, Filipendula
palmata, a more modest 2-4 ft tall.  Liatris, gayfeather or blazing star,
is another possibility from our lists of native species, and as a bonus,
it dries nicely for winter bouquets.

Other tall possibilities for moist soils:
         Anemone hybrida, japanese anemone (1-5 ft)
         Thalictrum rochenbrunianum, a meadow rue (3-5 ft)
         Physostegia virginiana, flase dragonhead (4-5 ft)
         Astilbe tacquetii, astilbe (3-4 ft)
         Hibiscus moscheutos, rose mallow (3-8 ft)
         Hibiscus coccineus, scarlet rose mallow (6-8 ft)
         Dictamnus albus, gas plant (2-3 ft)
         Chelone lyonii, pink turtlehead (2-3 ft)
         Mimulus lewisii, lewis monkey flower (2-2.5 ft)


For dry soils:
          Malva alcea, hollyhock malva, 2-4 ft
          Saponaria officinalis, bouncing bet (1-3 ft)
          Sidalcea malviflora, checkerbook (1.5-3.5 ft)
          Galega officinalis, goat rue (2-3 ft)
          Centranthus ruber, red valerian (1-3 ft)
          Elsholtzia stauntonii, staunton elsholtzia (4-5 ft0
          Veronica virginica, culvers root (2-6 ft)
          Echinacea purpurea, purple coneflower (2-4 ft)
          Monarda fistulosa, wild bergamot (3-4 ft)


RERUN OF LAST YEAR'S SERMON ON LYTHRUM:

The main problem with purple loosestrife in US and Canada is that it
establishes in very dense stands of up to 80,000 stems per acre. Each
stem, if allowed to flower, can produce up to 300,000 seeds, which are
dustlike, and can blow for miles. In addition to this, bits of stems or
roots from the parent plants (which can be 6 ft tall and 4 ft wide) will
easily root and form new stands by vegetative reproduction.

The US Wildlife Refuge system estimates there are currently about 400,000
acres (625 square miles or about 162,000 HA) in 26 states that are
infested with purple loosestrife or hybrids; the estimated cost is $45
million a year in control measures and lost forage. The plant outcompetes
such species such as our native cattails, which are used as food, nest
sites and cover for a variety of birds, muskrats, turtles, and many other
species.

Three insects native to Europe were released in a few areas in 1992 as
control measures; two seed-eaters and one root weevil. All seem to be
quite specific to L. salicaria, and refused to eat other plants and seeds
in lab tests. They hope that within a ten year period, the munchers can
reduce the purple loosestrife populations to 10% of their current number
of plants in about 90% of the current range. So far, there's some
encouraging data, but it's sure not to that level of control yet. The
choice to release these came down to a balancing act between the possible
side effects of these insects, the cost of current control measures, the
expected spread of purple loosestrife, and the environmental damage caused
by control measures like repeated hand pulling of the plants or use of
glyphosate.

End of Kay's post ==========================================

Jaime Knoble
NW NJ, zone 6
jknoble@warwick.net
"Our knowledge can only be finite, while our ignorance must 
necessarily be infinite." Karl Popper.
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