RE: monarch butterflies



On Tue, 25 Jan 2000, Randall, Rod wrote:

> Certainly a worthy cause but please be 
> aware that a few species of Asclepias
> (or  Gomphocarpus) are quite nasty 
> environmental weeds that also impact
> on pastures.  The plants are quite toxic 
> and the latex sap can blind if it gets in your eyes.
> The seed are produced inside rather 
> attractive swan shaped pods, 
> hence another common name, swan plant, 
> and when mature sally forth on silken threads
> all very pretty but highly invasive.
> 
> Caution is advised when considering planting 
> these shrubs as over 20 species are listed
> as toxic in the USA (by the FDA and University 
> of Idaho) and several are listed as weeds.
> They contain cardenolide type cardiac glycosides and
> galitoxin that can poison cattle that inadvertently eat the seedlings 
> amongst mouthfuls of grass.  
> They are also common causes of child poisonings due to the sap
> when children play with the flowers and pods
> (Sally Wilson, (1997) Some Plants are Poisonous.  Reed Books)
> 
> We have a lot  school teachers ringing us up wanting to grow
> swan plant to provide food for monarch butterflies, 
> they know the plant is a weed but seem
> to think it will be all right for thier purposes, 
> and they still want to know where to get the plants from.  
> Really frustrating for us to deal with these enquiries.
> 

I believe Rod is writing from the experience of weed science in western
Australia, and he may have non-indigenous Asclepias in mind...

It should go without saying that the responsible thing is to 1) plant
local natives [on the Pacific slope of the US, this is usually Asclepias
speciosa], or well-behaved garden plants like A.tuberosa.

A. speciosa is a native species here [Willamette Valley, western Oregon],
and highly persecuted by agriculture, by road maintenance, and shopping
malls. The few plants that survive to
mature size are usually located by monarchs, and they have several other
quite interesting insect customers -- all jewelled since the mikweed's
toxicity is conferred on their consumers..

Last year, I participated with a number of native plant enthusiasts in
salvaging some of  a large population of A.speciosa from commercial
development, and in distributing seed to land-owners who wanted to
re-establish the Willamette Valley as a viable area for migrating
monarchs.  I don't anticipate a weed problem to develop, but in fact 99
percent of the plant life the milkweeds will displace is non-indigenous,
and plenty of it COULD hurt someone if they tried hard enough [see the
Norse fable of the mistletoe arrow].

A number of native plants are listed as noxious weeds in the western US
without much regard  to the actual problems caused -- which are often
either non-existent or the direct result of overgrazing [cows, horses, and
even sheep are not such fools as to consume alkaloid-bearing plants if
there's anything else left toeat].

Although the monarch migration west of the Sierra/Cascade axis is not as
spectacular as the eastern flyway, this ancient pattern deserves to be
preserved, and it IS very threatened by suburban and agricultural
development.

As to concerns with toxicity and corrosive sap, I should point out that
milkweeds never seemed to be a problem with rural youth in the
pre-litigation era in the US:  see Aldo Leopold for the value of
growing up understanding that everything isn't set there for humans
convienience..


I respect Rod's insistence on caution in trafficking in non-indigenous
plants, but I don't think he's in a position to judge the American monarch
plant projects.

loren russell, corvallis, oregon
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