[PCA] strict natives vs cultivars
MALawler at aol.com
MALawler at aol.com
Wed Apr 9 11:19:18 CDT 2008
We just had a very thoughtful and lengthy discussion of this topic in
Virginia; I've copies the emails below; there are some good citations, too.
From: cecropia13 at msn.com
Sent: Sunday, March 16, 2008 8:14 PM
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Subject: Re: cultivars
Nick and John,
Thanks for your thoughts on cultivar-clone issue. In my experience, clones
or cultivars of native plants from gardens don't immediately, via
pollinators, alter the genetic structure of nearby wild plants - although they
certainly have the potential to do so if the nearby native plants are close enough to
be visited by the same pollinators. Of course, they don't alter the genetic
structure of the existing flowering plants, only the offspring of those
plants. In a short time, especially with easily pollinated plants like Asters,
etc., one could have innumerable seedlings that would no longer be considered
"natural" and would be spreading throughout the natural landscape.
Consider species of native Rhododendrons. A native azalea specialty nursery
will usually grow most species that occur in a myriad of habitats from the
coastal plain, piedmont, and mountains or from larger geographic areas (i.e.
Florida species, Smoky Mountain species, New England species, etc.). Many
overlap in blooming periods, especially in garden or nursery settings, often
leading to cross-pollination and numerous, unnamable hybrids. Take a look at
the Woodlander's Nursery catalog and you'll see many of these plants offered
for sale - all deliberate or accidental crosses resulting from pollination of
true species in close proximity, i.e. Rhododendron sp. #3, #4, etc. If one
of these or similar plants was to be promoted as a "natural selection" or
"cultivar" and therefore sold in mass quantity and planted near wild populations,
it could definitely pollute those populations and degrade the natural
landscape. (Also compare the cross-mixed species of Echinacea - some
federally-listed for their uniqueness/identity/rarity - that are sold by nurseries, which
are no longer true to the species but which carry genetic material from
different regions of the country, from different habitats, etc. Based on
observation and reports, I can say that if Echinacea purpurea was planted near E.
laevigata and they inter-crossed, the offspring would be composed solely or
mostly of E. purpurea, with E. laevigata being essentially outcompeted
genetically.)
Numerous clones or cultivars of Aster novae-angliae definitely mix in the
garden and nursery (though "Purple Dome" appears to be sterile) and can spread
from garden plantings to pollute native populations. Fortunately, this
species is relatively rare in suburban and urban areas, but occasionally one
finds a "wild" plant or population that is pink or whitish or striped, etc. - all
indications that the plant has crossed with a garden cultivar. (Most Aster
novae-angliae offered by eastern native plant nurseries are not true to the
species for this very reason. They have hybridized so much that they do not
represent the type for the species anymore - what we all should be interested
in, not the weird or unusual, like "Ice Ballet" Asclepias incarnata, etc.)
Should one of Richard Jayne's mountain laurel selections - a dwarf with
reddish flowers, say, selected from Maine, be planted in or near natural Kalmia
in North Carolina? Most restoration ecologists would say emphatically no.
There is and should be always maintained a difference between ornamental
horticulture and ecological restoration. Why are native plant societies so
fascinated by cultivars and clones when they aren't natural, at least in their
application, and there are so many good choices for local, appropriate material
at hand. (Collect seed, take cuttings, contract grow from local sources,
rescue plants, etc.) Factor in the potential and documented, in some cases,
problem of polluting local, native populations and one has an iron-clad case
against the use of cultivars and clones - at least in and around any natural
areas.
The main purpose of native plant societies, in my opinion, is to promote the
real and the natural and its conservation. (See www.VNPS.org archived Stan
Shetler article.) Many of these plants and their habitats have enough
threats against them without people fooling around needlessly with plants that
have the real potential to seriously alter what exactly is real in nature. From
my perspective, there is nothing more deflating than to find garden escapes
or inappropriate species in otherwise pristine or healthy natural areas.
Rod Simmons
Rod (et al.):
I think we are essentially in agreement. I’m hard pressed to find an
example, either from the literature (not that my knowledge of plant conservation
literature is all that deep), or from personal experience, of garden clones or
cultivars of native species mixing with truly wild plants and causing some
measurable alteration of the wild plant’s genetics. It does seem possible,
though.
For cultivars that are nothing more than a particular selected genotype from
a wild ancestor, I find it hard to generate much concern about potential
impact of cross-pollination between the cultivar and nearby wild plants since
the cultivar’s genes already exist in the wild population. One may fret about
altering the frequencies of this or that allele beyond what would have
happened in the total absence of human intervention . . . but where do we find the
total absence of human intervention anymore? Our collective human footprint
has brought about so much change in nature that the possible impact of
planting a cultivar of a native plant in your back yard seems infinitesimal in
comparison. And besides, planting a cultivar of a native plant has got to be
better, in the overall scheme of things, than growing another crepe myrtle or
clump of lily turf.
Cultivars that are hybrids between multiple species are much more artificial
or non-natural than the above example. As the artificiality of the garden
plant increases, so should our wariness about escape of genes into the wild.
Yes, I believe that it would be unwise to plant masses of hybrid azaleas in
proximity to closely related wild species in a natural setting. But, as I
mentioned in one of my earlier posts on this thread, in a densely populated
suburb distant from native vegetation, I suspect that the risk of cross
pollination between hybrid and wild azaleas would be quite low. Personally, I would
not worry about undue impact in such a situation. But if asked as a
representative of VNPS, I would still suggest growing native plants!
>From the little searching that I did recently, the phrase “genetic pollution”
seems most closely associated with genetically modified crop plants and the
transfer of exotic genes via the GM crop to its wild (or less highly
refined) relatives. The classic case involves genes from genetically modified corn
allegedly showing up in corn fields in Mexico, near the ancestral homeland
of the crop. Less commonly, I find the term used in the context of alien
(exotic, non-native) plants (or animals) crossing with natives and exerting a
genetic impact via interspecific hybridization. Certainly, these are troubling
situations, but different from the origin of this whole cultivar discussion:
cultivars of native plants having some potential impact on wild native
plants.
Yes, VNPS is at its core a conservation organization properly focused on
nature and the preservation of natural systems. But the whole gardening thing
will not just go away. Many VNPS members enjoy growing at least a few native
plants in their yards. And many members of the general public will look to
us for advice about growing native plants—and these people are probably our
hottest prospects for recruiting new members! We need to have sensible advice
on hand, for ourselves and for the general public.
You mention the deflating/depressing impact of finding “garden escapes” and
“inappropriate species” in natural areas. I certainly share the sentiment.
But in my experience, the garden escapes and inappropriate species are
never cultivars of native species—they are always exotic aliens, and I think we
are all in agreement that invasive exotics are detrimental.
Please understand, I’m not saying that it cannot happen, but I still would
like to hear of actual cases (not hypothetical situations) in which cultivars
of native plants growing in gardens have altered the genetic constitution of
nearby wild plants in a natural habitat.
John
W. John Hayden
Professor of Biology
Department of Biology
University of Richmond
Richmond, VA 23173 USA
phone - 804-289-8232
FAX - 804-289-8233
jhayden at richmond.edu
_http://www.richmond.edu/~jhayden/_ (http://www.richmond.edu/~jhayden/)
John,
Though, personally, I have nothing to contribute to this discussion, as I
look through the newsletters and publications VNPS receives, today I find in
the California Native Plant Society Bulletin Vol. 38 No. 1 January-March 2008,
an article on page 1, continued on page 6 “Considerations When Planting
California Native Plants.” It is not yet online in their archives, but will be.
Their Conservation Conference of 9/8/07 featured Deborah Rogers,
conservation geneticist with the Genetic Resources Conservation Program, U. of C.-Davis.
The CNPS in 2001 addressed the issue:
_http://www.cnps.org/cnps/archive/landscaping.php._ (http://www.cnps.org/cnps/archive/landscaping.php.)
Rogers’ full presentation, along with the others given at the conference,
are now available on the CNPS website – access by clicking on “Conservation”
and then, on “2007 Santa Cruz Conservation Conference Proceedings.”
Other links:
Fact Sheets on Genetic Conservation:
_http://www.grcp.ucdavis.edu/projects/FactSheetdex.htm_ (http://www.grcp.ucdavis.edu/projects/FactSheetdex.htm)
Genetically Appropriate Choices for Plant Materials to Maintain Biological
Diversity: _http://www.fs.fed.us/r2/publications/botany/plantgenetics.pdf_
(http://www.fs.fed.us/r2/publications/botany/plantgenetics.pdf)
Native Plant Journal, Fall 2004:
_http://www.nativeplantnetwork.org/journal/_ (http://www.nativeplantnetwork.org/journal/)
Those who are closely following this discussion might like to learn what a
fellow native plant society has to share. (Even though they are located on the
opposite coast.)
Nicky
Nicky and John (et al.),
Thanks for your comments. Nicky, I'm glad you sent the California Native
Plant Society article, I thought that was good as well.
This native plant cultivar and hybrid debate has been going on a long time
now, but seems to have been thrust back into the forefront locally, with the
Irvine Conference in Baltimore last year and the Lahr Symposium coming up
next week (also lots of articles).
I certainly agree that VNPS and MNPS locally (and many native plant
societies as well) are "conservation organizations properly focused on nature and the
preservation of natural systems." I also think gardening is a fine thing -
something which I personally enjoy. However, as conservation and not
gardening organizations, when "asked for advice about growing native plants," as
John says, we definitely "need to have sensible advice on hand." The most
sensible advice about using native plants we can give, based on numerous case
studies, empirical observations, research, and a sizeable number of red flags,
is to plant native species - if one wants to plant - that are naturally found
in very close proximity to where they will be planted and that are true
species. (Native by definition excludes cultivars and man-made hybrids as the
definition of "native" is that which is local and natural) Besides, there are
numerous native plant nurseries that grow material from local stock, so
sourcing appropriate plants is no longer a problem.
Different nurseries supplying the demand for new/unusual plants to gardeners
(mainly in last decade or two!) have unleashed incredible destruction on our
wild plants and places. Dogwood Anthracnose imported by way of Kousa
Dogwood for landscape use, Sudden Oak Death from imported ornamental stock, Emerald
Ash Borer, Hemlock Adelgid, etc. Those are some of the prominent ones in
the news currently, but there are scores of others that are off most radar
screens.
We have more than enough examples of what harm moving and mixing plants
around can do and I think we should promote, when the topic of gardening with
native plants comes up, only what is truly native and not cultivars (no this
isn't a "purist" policy it's reality!). Moreover, we're not gardening advocates
and there is more than enough justification to be wary of cultivars, just as
some exotic plants, and to not promote them. Promoting cultivars is the job
of the nursery industry, not ours. Our job is to stick with what's natural
and real.
Rod
p.s. I've included below some more info and links on the subject.
1.
_www.conps.org/pdf/Horticulture%20&%20Restoration/nativeplantdef.PDF_
(http://www.conps.org/pdf/Horticulture%20&%20Restoration/nativeplantdef.PDF)
2.
"Be wary of seeds from cultivated E. angustifolia if grown in areas with
native or cultivated populations of E. pallida, E. atrorubens, E. angustifolia
var. strigosa or E. simulata. Native American Seed (Company) has collected
seed in the Dallas/Fort Worth environs from plants that fit the description of
E. angustifolia var. strigosa, which is thought to be a hybrid between E.
angustifolia and E. atrorubens. The achenes were larger and rougher than seeds
of E. angustifolia var. angustifolia. (The isolation distance to avoid
hybridization has not been determined. It is likely that wild bees, honeybees and
other pollinators can transport pollen several miles between plants). The
geographic range of Echinacea species is illustrated in McGregor, R.L., 1968, "The
taxonomy of the genus Echinacea (Compositae)," Univ. Kansas Sci. Bul. 48,
and in Barker, W.T. et al., 1977, Atlas of the Flora of the Great Plains, Iowa
State University Press.
More importantly, however, cultivated sources have potential problems of
hybridization and contamination with other seeds that are less likely to occur
with wild sources. One seed grower has addressed the problem of hybridization
by arranging to have E. angustifolia grown in an isolated location in New
Mexico in 1996."
Source: biomicro.sdstate.edu/reesen/Echinacea/newsletter.htm
3.
Cultivars of Native Plants
In the wild, plants have been discovered that have one or more ornamental
characteristics that are superior or substantially different compared to the
typical plant of that species. When these selections are propagated and
produced in a manner to preserve the desirable characteristics, they are often
referred to as cultivars. Cultivars typically are evaluated under landscape
conditions to determine their potential use in residential and commercial sites.
For cultivars derived from naturally occurring populations outside of Florida
or areas bordering Florida, cultivar origin is an important issue to consider
as mentioned previously. For example, a dogwood cultivar derived from a
natural population in the northeastern U.S. would not be appropriate to use in
Florida.
The other issue to consider is man-made cultivars of native plants. Many
native plant experts and enthusiasts do not consider man-made cultivars as being
native, although it might be argued that selections or hybrids could have
occurred under natural conditions. It is very unlikely, however, that man-made
selections or hybrids with "double flowers" (the reproductive parts of the
flowers develop into petals so that there appear to be twice the number of
petals) would be found in the wild for species that rely on seed for
reproduction. Such species with "double flowers" would not be able to reproduce.
Use of cultivars in restoration or reclamation should be done with caution
because genetic diversity could be very limited. Potential consequences of
inbreeding and outbreeding depression also need to be considered.
Source: Native Plants: An Overview Jeffrey G. Norcini, University of
Florida
4.
CONSERVATION OF GENETIC RESOURCES
Everyone involved with the selection, use and promotion of new native plant
species and cultivars and/or any of their close relatives must be fully aware
of the potential negative consequences of their use in gardens and
landscapes. Most of these concerns center around the issue of conservation of genetic
resources and the genetic pollution of native plant populations in the wild.
Three examples from the California flora will serve to illuminate this issue.
Nevin's Barberry [Mahonia (Berberis) nevinii], an extremely rare plant in
nature, is found in widely distributed and ecologically varied small
populations in southern California. It is, however, a relatively commonly seen
landscape plant throughout the state. A molecular level study of these plants showed
that there is little to no variation present in the gene pool. Therefore,
the seed source of plants to be planted in the vicinity of the remaining
individuals in the wild is not of concern--there will be no adverse consequences to
the gene pool.
The California dandelion (Taraxacum californicum) from the wet meadows in
the San Bernardino Mountains is a rare plant whose continued existence is
threatened by ongoing hybridization with the common European dandelion
(Taraxacum officinale), a weedy pest plant that is common throughout the range of the
rare species.
The Monterey pine (Pinus radiata) is known from five geographically isolated
populations (three are from central coastal California and two are on islands
off Baja California). This tree is a significant forest tree in the southern
hemisphere, particularly in New Zealand. Material from all five populations
has been grown together on a massive scale in New Zealand, such that the
primary seed source of Monterey pine (even in California) is from New Zealand.
The issue of primary concern here is that the "mongrel" Monterey pines of New
Zealand mixed origin will genetically pollute the "pure" native stands of
these trees, such that the unique genetic character of the California
populations will be lost due to homogenization of the gene pool over time (the Baja
California populations are not threatened in this way at this time).
Source: Xeriscaping: Sources of New Native Ornamnetal Plants Bart C.
O'Brien
5.
_www.ca.uky.edu/agc/pubs/for/for98/for98.htm_
(http://www.ca.uky.edu/agc/pubs/for/for98/for98.htm)
6.
_www.ser.org/pdf/SER_restoration_genetics.pdf_
(http://www.ser.org/pdf/SER_restoration_genetics.pdf)
John, Helen,
I agree with John. Policy is set after presentation of pros and cons that
are developed by a balanced committee (diverse data, information and
viewpoints heard) and >then< present findings to the board. I have been following
this as an informed discussion, not as an exchange to set a formal VNPS policy.
This subject is fraught by diverse nuances and opinions and this is not a
simple subject that can be encapsulated into one or two paragraphs after this
series of e-mails
Surely we do not want a policy that tries to restrict native plant cultivar
sale by the nursery industry. We can educate our members/public/natural
resource managers to use care where cultivars are introduced. I would not want to
have us expend our meager time and funds on a Quixotic crusade. Is the
idea, calling cultivars of native plants “non-native plants” and to consider
them inappropriate for use?
We know you are not some crazy kook, John. Nor are the other participants.
Good science from John is welcome as we try to understand the use of native
plants and native plant cultivars in home gardens/landscapes, public
gardens/trails, and restoration of natural areas. By education, we can first
thoroughly educate ourselves and then lead the gardeners, natural resource managers
and the nursery industry to wise use of cultivars of native plants. A well
worded policy could very well evolve from such a study. I believe we can educate
about this subject without a formal policy.
Helen, if you are calling for a VNPS policy, you would bring the request
first to the EC who would involve the chairs of committees involved in the
subject, and then the next step could send it to the board and if they agree, a
committee would need to be named to gather the information, present a report
and recommendation to the Board who would need to study and discuss the
recommendation before voting. I am not saying that we should not do this, but I
feel we are not ready for that final writing and adoption of a policy.
For instance, when VNPS formed a policy concerning use of herbicides, it was
an exhaustive study commissioned by the board and done by Cris Fleming,
Faith Campbell and others, that formed a very well worded, rational statement to
the effect that while we do not condone all use of herbicides, there are
situations that we feel it is appropriate to use with proper controls by trained
personnel to apply it. (I believe that natural resource managers proved a
need for its use in control of invasive plants under some specific conditions.)
And, I believe that there are far, far more dire imminent threats to our
native plant populations than the use of native plant cultivars in home and
urban botanical gardens. (Not placing them in natural wild situations is easy to
support.) It is interesting to remember that nature creates "cultivars."
What was it that Hal Horwitz said, in citing the huge diversity in the
orchidacea family, that in nature when faced with change, 'adapt, move or die'?")
I would prefer our efforts to form policy focus on loss of habitat to
expanding urban/suburban development that erases the natural Virginia landscape.
(i.e. The town centers and housing developments that remove all trees and
vegetation, level the terrain, place streams underground on hundreds of acres of
Virginia landscape.) Or, global warming. Or, removal of southwest Virginia’s
mountain tops for coal export. We each have our issues.
Kind thoughts to all, Nicky
Rod (et al.)
In my previous message (19 March message) I thought we were largely in
agreement, but now I fear we have entered the realm of cross-talk. Perhaps we are
not really talking about the same things. I initiated this dialog in
response to Helen’s question about cultivars. I endeavored to explain (13 March
message) what cultivars are, which is a tricky thing, because the origin and
genetic makeup of cultivars can be so different from one example to the next.
Further, I understood the context of Helen’s question to concern
merchandise for a plant sale, so I assumed that if cultivars were involved, they would
be cultivars of native plant species, and their use would be as garden
subjects, planted in someone’s yard—and certainly not in a natural habitat nor to
be used in an ecological restoration project. Context matters. If I got the
gist of Helen’s question wrong, or if anyone who has kept up with this
exchange has misunderstood the intended context of my words, then I am sorry for
the confusion.
Based on the content of your last message (22 March), it seems to me that
you have addressed a range of problems much broader than the specific matter of
cultivars of native species in gardens. Your 22 March message cites
examples of invasive exotic species (aliens) and artificial inter-species hybrids,
along with some very reasonable principles of conservation genetics in the
context of ecological restoration. Other than hybrid Monterey Pine (Pinus
radiata), every other example contained in that message seems (to me) extraneous
to the topic of native plant cultivars and the possible/potential negative
impact of planting them in garden settings. See material below the stars (***)
for my comments on specific examples cited in your 22 March message.
I think it only muddies the water to equate cultivar with any plant that has
entered, at any point in its history, cultivation. Kudzu and Japanese
honeysuckle were, at one time, intentionally cultivated, but that fact alone does
not make these plants as we encounter them in the landscape “cultivars.”
That simply is not the meaning of the word. In an attempt to clarify this
distinction: Most Japanese honeysuckles have ordinary green leaves. There
exists a cultivar of Japanese honeysuckle called “Mint Crisp” that is
distinguished from wild populations by a creamy speckled variegation pattern on the
leaves. The plant that infests our woods and fields is Lonicera japonica, a
nasty invasive exotic species; one particular genotype of that species is known
as Lonicera japonica cultivar ‘Mint Crisp.’ The Japanese honeysuckle that
infests my woods is not a cultivar, L. japonica ‘Mint Crisp’ offered for
sale by some nurseries is. (Please note: I am certainly neither condoning nor
promoting the cultivation of either plant—species or cultivar – just noting
the distinction between the two.)
Perhaps I should have provided more explicit examples of cultivars of native
species. Here are a few. There exists a form of Cimicifuga racemosa that
has unusually heavy deposits of anthocyanin pigment in the leaves; these
dark-leaved plants are known as Cimicifuga racemosa cv ‘Atropurpurea.’ There
are numerous selections of red maple based on the specific hue of their fall
color; thus we have Acer rubrum cv ‘Red Sunset,’ Acer rubrum cv ‘October Glory,
’ Acer rubrum cv ‘Autumn Flame,’ etc. There is a selection of river birch
with shaggier than usual exfoliating bark that is known as Betula nigra ‘
Heritage.’ As I attempted to explain in my first message, these examples of
cultivars represent, essentially, just small subsets of the genetic diversity
that occurs at large in populations of their “parent” species. While it
remains in my mind a theoretical possibility that planting this sort of cultivar of
a native plant in a garden setting could have unforeseen negative
consequence for truly wild and natural populations, it is difficult – in most cases –
to conceive what the nature of that harm could possibly be. I see no reason
not to plant these sorts of cultivars derived from native plants in gardens.
Never did I advocate planting this sort of cultivar in natural settings, nor
did I advocate use of cultivars for ecological restoration.
Yes, it would always be prudent to consider with great care the potential
impact of introducing any plant in the urban-natural interface (to borrow a
concept from the California Native Plant Society page that Nicky cited). So,
for example, it would not be wise to plant purple coneflower (Echinacea
purpurea) near populations of our rare native Echinacea pallida. Similarly,
restraint should be exercised in planting hybrid Monterey Pine near the few remnant
and genetically isolated natural populations of the species (in California).
Of course, rare plants are rare and therefore likely to be distant from
most backyard gardens.
* * *
Comments on examples cited in the 22 March message.
Cornus kousa, dogwood anthracnose, sudden oak death, emerald ash borer, and
hemlock wooly adlegid – these are all cases of alien plants and animals
having negative impacts on native plants. No argument, these are real problems,
but they constitute an issue different than the origin of this exchange about
cultivars of native plants.
1. Colorado Native Plant Site:
_http://www.conps.org/pdf/Horticulture%20&%20Restoration/nativeplantdef.PDF_
(http://www.conps.org/pdf/Horticulture%20&%20Restoration/nativeplantdef.PDF)
I think the distinctions made therein between “native plant” and “local
native plant” are useful.
The following paragraph is copied directly from that same site:
“Native species are often "improved" by selection and propagation of
individuals for certain traits, such as early flowering or taller flower stalks.
These selected native plants are called cultivars. Cultivars are often not
adapted to local environmental conditions and may not thrive. Research has shown
that some cultivars will breed with local native plants and decrease a
population's fitness or ability to survive in an area. No one really knows what
effect these cultivars will have on the wildlife that depend on local native
plant species for food. If a local native plant's bloom period, color, or frost
hardiness is changed, it could have a drastic effect on the hummingbirds, bees
and other wildlife that may utilize them.”
Despite the assertions made in the third and subsequent sentences of that
paragraph, I note that no specific examples of native plant cultivars harming
(decreasing fitness) of local native plants are provided. I wonder if the
word cultivar was used (inappropriately) in reference to any cultivated plant?
2. Coneflowers, species of Echinacea: E. angustifolia, E. pallida, E.
atrorubens, or E. simulata.
Distribution maps for these coneflower species (and others) can be found at:
_http://www.kbs.ku.edu/people/staff_www/kindscher/echinacea/maps2.htm_
(http://www.kbs.ku.edu/people/staff_www/kindscher/echinacea/maps2.htm)
Quick perusal suggests that ranges of these species are at most only
modestly overlapping in nature. Grown in proximity in a common garden, they will
hybridize. So if a commercial grower offers seed from multiple coneflower
species it is quite likely that some significant proportion of the seed will not
be “true.” No argument here. But this is a question of mixing species
from different geographic locations, not the issue of a cultivar of a (single)
native species causing “harm” to the species at large from which it was
derived. I did acknowledge in my first (13 March) message that interspecies
hybrids could pose a risk of introducing new/different genes into wild populations
(see 4th paragraph from the end of that message).
3. Extract from “Cultivars of Native Plants” by J. G. Norcini.
I find no real argument here. Of course, “double flower” cultivars that ar
e sterile (because stamens or carpels or both have been converted to petals)
will have absolutely no impact on the population genetics of nearby
wild/native members of the same species. If someone finds this sort of double flower
appealing, there should be no worries about planting them in his/her garden.
There is one sentence: “For example, a dogwood cultivar derived from a
natural population in the northeastern U.S. would not be appropriate to use in
Florida.” I don’t know what the author intended, but the northeast dogwood
simply might not grow well in Florida, so it could be inappropriate that way.
And it would certainly be inappropriate for ecological restoration in Florida
. . . but (again) that is a different issue. I have been saying all along
that ecological restoration should be based on local sources (see my first
message – 13 March – third paragraph from the end).
4. “Conservation of Genetic Resources” from xeriscaping article by B. C. O’
Brien
Mahonia/Berberis nevinii example – O’Brien sees no problem in planting the
native plant (in California) and neither do I.
Taraxacum californicum example – this is a problem with an invasive exotic
crossing with a rare wild plant, and I think we all agree that this is bad.
Our common weedy invasive dandelion is not a cultivar.
Monterey Pine – Pinus radiata example – OK, here is a case where the
cultivated (infraspecific) hybrid (derived from a few genetically isolated sources
of a rare species) could have an impact if planted where it could interbreed
with the naturally occurring populations. I will not take a position on
whether that impact would be good or bad . . . I can see both arguments!
5 _http://www.ca.uky.edu/agc/pubs/for/for98/for98.htm_
(http://www.ca.uky.edu/agc/pubs/for/for98/for98.htm) The only reference to “cultivar” that I
could find on this page refers (fleetingly) to hybridization of coneflowers (see
number 2 above).
6. _www.ser.org/pdf/SER_restoration_genetics.pdf_
(http://www.ser.org/pdf/SER_restoration_genetics.pdf) The title of the article is “Introduction to
Restoration Genetics.” It looks like a very useful source of information. The
term “cultivar” does not appear in the article. “Genetic pollution” occurs
once, in a context that reinforces the principle that best practice is to
use local plant resources when undertaking restoration projects. I have no
argument with that.
John
W. John Hayden
Professor of Biology
Department of Biology
University of Richmond
Richmond, VA 23173 USA
phone - 804-289-8232
FAX - 804-289-8233
jhayden at richmond.edu
http://www.richmond.edu/~jhayden/
John et al,
Thanks for your comments. I realize that this discussion quickly gets
extremely complicated and dense - much like the discussion on "what is native"
that so many of us spent so much time trying to clarify years ago, especially
when our native plant societies were being formed. I also realize how some of
these topics, which I believe to be strongly related and illustrative of the
same central argument, can appear at cross purposes or confusing to some.
In my opinion, examples like the Purple Coneflower, Monterey Pine, various
cultivars, and even Kousa Dogwood (referred to below) all speak to the same
point: native plant societies should protect and be advocates for their local
native flora and habitats. The natural and not the artificial. With all the
planting going on these days, the threats to natural populations and habitats
increase because most (if not all) of the plants used are not from local
sources and are not appropriate/native to that locality. This is what the
Purple Coneflower, Monterey Pine, and Kousa Dogwood examples illustrate.
Ideally, a native plant society should not, in good conscience, sell or
advocate the use of "native plant" cultivars as native plants. Instead, we
should tell folks, if these plants happen to be sold at one of our plant sales,
that these really are not native plants mainly because a) many are man-made
hybrids, i.e., Tradescantia x andersoniana, Aronia x brilliantissima,
Amelanchier x grandiflora, etc. (not to mention grafted Pink Dogwoods, hybrids between
American and Oriental Chestnuts and American and European Elms, etc.) and b)
those cultivars that represent small genetic subsets of larger diversity,
like Solidago rugosa "Fireworks", Tiarella cordifolia "Sliprock", Ageratina
altissima "Chocolate Ruffles", etc., are mass-produced, atypical plants that are
not native or appropriate outside the place they were discovered. Moreover,
those atypical varieties are extremely rare/isolated in nature and definitely
not the norm for the species. We should always maintain a strong
distinction between the ecological and that which is gardening. Gardening, whether
with native plants, exotics, cultivars, or not, is still gardening. It's a
wonderful pursuit in its own right, but really a separate enterprise from what a
native plant society is about. In addition to being concerned with "what is
native" and "whether or not a cultivar will impact native flora", we should
also be equally concerned with the related and important question of where a
plant is native to, also taking into account a species' rarity.
I personally do not have a problem with people planting whatever is not
invasive or ecologically destructive in their own gardens. Too often as we all
know, however, some plants find their way into local natural areas; hugely
destructive problems like the Emerald Ash Borer pop up as volumes of nursery
stock arrive for landscaping purposes; and, occasionally, some cultivars can
negatively impact local natural areas. (In the Washington, D.C. region,
Hydrangea arboresecens "Grandiflora" has seeded into Soapstone Valley of Rock Creek
Park, Sugar and Red Maples commonly seed from nursery stock, seedlings of
cultivars of Phlox paniculata are fairly common; seedlings of Tradescantia x
andersoniana have been noted, and so forth. Moreover, I have seen on several
occasions inappropriate native plants and cultivars that were purchased at
native plant society plant sales and planted in natural areas as restoration
projects. Upon inquiring, I was told that the plants were purchased without any
advice, caution, etc. at the plant sales with grant monies earmarked for
restoration. They thought they were native and suitable since the local native
plant society sold them! (The problem isn't as much whether John or I
advocate the use of these plants in natural areas - we don't! - but the fact that
on numerous occasions they do get planted there or escape there and some of
this is our fault!) We need to include a disclaimer (or at least a comment)
at all of our native plant society plant sales that none of the plants offered
(exceptions notwithstanding) are appropriate for restoration purposes with a
brief explanation of why that's so - that they are for home gardens only!
In short, we just have to be careful about what we plant, ask whether it's
really necessary to plant a particular plant, and give those less informed good
and clear advice on how to be a good neighbor to surrounding natural areas.
Rod
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(http://travel.aol.com/travel-guide/united-states?ncid=aoltrv00030000000016)
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