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We had heard of Monarchs overwintering along the Texas coast and finally found two such groups
in Calhoun County during the winter of 2000-2001and again in 2001-2002. These sites are near
bays, with a few acres of trees for shelter (some oak) and nectar sources nearby (usually lantana).
From late December to mid February, we have been unable to find any viable wild, native milkweed
in the area. We have watched some Asclepias oenotheroides into January near Port O'Connor but
with a light freeze, it is also gone. We don't know what milkweed might be growing on the Gulf barrier
islands or along shores of the warmer bays.
In 1996, we knew of only one milkweed and that was the non-native Asclepias curassavica that is
planted in many, many flower beds and butterfly gardens. Altus spied our first "real" milkweed in
March 1998. It was in April that year as I stood there proudly showing Bill Calvert our backyard
curassavica when he said something to the effect: "Yes, but what about all the native milkweed?"
That is when our quest to answer "what about all the native milkweed" began, thousands of miles
of zig-zagging roads, lanes, and interstates across Texas.
Why all the fuss about the native milkweeds? Lincoln P. Brower, Research Professor of Biology,
Sweet Briar College, Sweet Briar, VA, posted these thoughts to the Monarch Watch Dplex list
in April 2002 and are used with his permission: "It may be a good idea to ask ourselves about the
wisdom of transplanting milkweeds (Asclepias species) to places out of their natural ranges. Each
milkweed species is chemically unique and biogeographically restricted. If people move the plants
around or transfer seeds, then there is potential for confusion with the loss of the native distribution.
Cardenlolides (the poisons in milkweeds that monarchs sequester) are often unique assemblages
within a given milkweed species and are useful for fingerprinting adult monarchs to their place of
origin ... so this ability could be lost, too."
The same thought for wildflowers in general is expressed in a sign over the display of seeds for
Texas native wildflowers at the Lady Bird Johnson Wildflower Center southwest of Austin, "Please
note the native range of each species. It is not environmentally responsible to plant outside of the
native range. So, please plant what's native to your region. Thank you!" (Their emphasis!)
A Texas Monarch Watch brochure several years ago said Asclepias curassavica, often called tropical
Mexican milkweed, doesn't seem to be native to Mexico or anywhere else nearby. It has "escaped"
and reports are it is naturalizing in several locations, possibly not just Texas. More and more we
are finding curassavica included as a Texas "native" in publications.
Curassavica is so easy to grow across Texas, it seems it will remain the milkweed of choice when
monarch larvae are raised at schools for the experience the students (and others!) will get ... and in
homes. But using curassavica to extend the natural season of monarchs in a region may not be wise!
A choice might be to plant some native milkweeds and cut back the curassavica when the milkweeds
native to the region die back (senescence) in January and February ... at least find and observe the
season of the native milkweeds of a particular region that are growing wild in pastures or roadsides.
Another choice in Texas might be to add two milkweeds to the butterfly garden that are natives,
Asclepias tuberosa and Asclepias incarnata. Seeds of both are available from several sources
and plants are available at times. Tuberosa is often mislabled curassavica ... pinch off a leaf,
curassavica "bleeds" the white, milky sap of milkweeds, tuberosa doesn't, sap is clear! Both
require a little more care in growing, but the results can be fantastic. Check "Seed Sources" for seeds.
Oenotheroides, asperula, and viridis can be grown in butterfly gardens ... much harder to do, but
can be done if the soil is matched to what they are growing in naturally. Find a farmer or rancher that
will let you borrow a few plants from his pasture in early spring and transplant a cylinder of dirt with
the young plant. Don't overdo it, try two or three plants and see what happens. Be sure to backfill the
hole! Communicate with the owner of the land as to what you are doing and why! This would be a
good time to see if you could get permission to come back and monarch the patch for the Monarch
Larval Monitorng Program or for the Texas Monarch Watch monitoring program.
If you raise any of the native milkweeds in your butterfly garden in Texas, please let us know what you
have found or experienced, what works or doesn't ... how, when, where, what variety. There are many
monarch watchers in Texas that have or care for butterfly gardens who would appreciate sources for
potted milkweed plants or tubers that are for sale to add to their landscape.
Photos and webpages by Harlen E. and Altus Aschen
Instructors at Victoria Christian School
Port Lavaca, 77979, Calhoun County, Texas
Copyright (c) 2002 All Rights Reserved
May be reproduced and used for educational purposes.