Plants > Biotechnology / PNTs > Consultations - Topics and Outcomes 

Environmental Risks of
Ornamental Plants

Risks posed by plants with novel traits

Wilf Nicholls
MUN Botanical Garden
St John’s, NL

Canadian Ornamental Plant Industry
(floriculture, nursery, Christmas trees, sod)

• Ornamentals are Canada’s most valuable crop (farm gate)
  • $1.795 b. (2002)
  • Wheat ($1.765 b.), canola ($1.625 b.)
  • http://www.agr.gc.ca/misb/hort/trends-tendances/pdf/ov02_03_e.pdf
• Retail sales, related industries (landscaping, floristry, design and architecture etc.
• Gardening is the most popular active pastime in N. America
• >100,000 jobs in Canada
• Tax generator – little in the way of tax relief for ornamentals/services

New Plants in Canada

• There is a constant demand for new plants, new products
• Canadian Ornamental Plant Foundation (COPF) collects royalties on 4,000 cultivars
• Registers an additional 250-300 per year
• Collects and distributes almost $2 m. per year to breeders and developers

Where do new plants come from?

Naturally occurring resource

• Interspecific variation
  • 270,000 angiosperm, gymnosperm species worldwide
• Infraspecific variation

Cultivar development
Sourcing variation

• Selection from natural variation in the wild (variation may be phenotypic)
• Selection from wild-collected seed (grown under uniform conditions to expose genotypic variation)
• Selection from chance/exptal hybridization
• Transgenics (nuclear, cytoplasmic)
• Mutagenesis (e.g. x-rays)

Rosa

• Genus of 120 species
• Breeding and selection has resulted in over 8,000 cultivars

New Plants

• Species (exotic or native)
  • Less numerous nowadays
• Newly discovered variants of species

Plants without novel traits (non-PNTs)
Governed by CEPA (Can. Envir. Protection Act 1999) through the "New Substances Notification Regulations"

Plants with novel traits (PNTs)

• Unusual variants
• Hybrids
• Transgenics, induced mutations etc.

Coming soon?

• Round-up Ready® petunias?
• Bt daylilies?

Don’t hold your breath!

What is a PNT?

• A plant which expresses a trait not present in plants of the same species cultivated in Canada or at levels outside the normal range in which those traits are expressed.

Therefore...

• A newly bred (non-hardy) marigold showing a new flower colour is a PNT
• A newly discovered prostrate form of a native tree (height falls well outside normal range for the species) is a PNT
• But...a newly imported species novel to Canada that exhibits traits common to that species (in its native distribution) would not be a PNT (CEPA)
• Their environmental risks are similar

Auditor General

• ornamental horticultural industry lacks awareness of the [PNT] regulations
• Risks posed by ornamental plants with novel traits need to be more formally assessed
• Difficult to ‘test’ for a plant with a novel trait
• PNTs ‘look’ like regular plants
• To know if a plant has a novel gene one must know what genes the species already has
• Infraspecific variation – novel traits?
  • Weeping, prostrate, variegated forms of conifers
  • Albino flowered angiosperms

Risks

• Invasiveness
• to spread, thrive and establish self-perpetuating populations in natural areas thereby changing the species composition and/or ecology of that area and/or native genomes
• Invasiveness may be physical or genetic
  • Competition for resources
  • Hybridization
  • Introduced or increased nitrogen fixation
  • Alteration of hydrologic cycles
  • Increased sedimentation
  • Increased frequency or intensity of disturbance cycles
• Imported pathogens, insect ‘passengers’ (CEPA)
• Invasiveness vs. weediness vs. persistence

Invasiveness, weediness, persistence

Costs of invasives

• Invasive species are the 2nd most serious threat to native plant communities (after habitat destruction)
• 27% of Canada’s flora are naturalized non-natives (over 50% Australia & New Zealand
• 50% of species listed as rare/endangered (Endangered Species Act) are at risk from competition/predation by exotics (Havens, 2002)
• Worldwide losses of food and fibre production 12%
• In U.S. (1994) economic impact of weeds estimated at $20 b.
• Pimental (2000) estimates $35 billion
• Havens (2002) quotes $138 billion

More numbers

• North America has about 2,100 species recognized as weeds – Weed Science Society of America
• 1,365 of these are non-native
• Randall (2001) estimates 18,500 worldwide
• Lists 958 "Garden Thugs" in Australian horticulture
• Includes many agronomic weeds e.g. Trifolium, Phleum, Brassica oleracea Taraxacum etc.
• Weeds vs. Invasives...dandelions vs. kudzu

Sources of invasives

Agronomic weeds

• Taraxacum, Linaria, Trifolium, Vicia, Hordeum
  • many are opportunistic and non-persistent
  • status as invasives debatable

Intentional introductions

• "good intentions gone bad"
• ornamentals, site rehabilitation, forestry species
• Individual instances of insanity
  • Reichard (2002): of noxious weeds intercepted at airports – 85% was in passengers’ baggage

Unintentional introductions

• ballast, packaging, soil movement

Horticulture...public enemy #1?

• Marinelli (1996) estimates that over half of all invasive plants in the U.S. were introduced as ornamentals
• Reichard & Campbell (1996) 85% woody invasives were/are ornamental or landscape plants

#1 priority limit the influx of new plants?

Yinger (2002) – "truth: the first casualty of war...know the enemy...and quit doing the stupid stuff!"

Hysterical perspective

• Misuse of U.S. agricultural land led to the use of oriental bittersweet, Japanese honeysuckle, Elaeagnus, Rosa multiflora for erosion control
• Florida names Japanese honeysuckle as a pernicious weed and advocates its eradication
• And yet...
• Alabama recommends 10:10:10 on wild Japanese honeysuckle to encourage deer browse (2003)

Porch vine

Lythrum

• Purple loosestrife arrived as packing material and medicinal plants in 1800’s
• Garlic mustard was never an ornamental

A few invaders of Canada

• Scot’s Broom
• Cytisus scoparius
• native to northwestern Europe
• serious invader of Gary Oak woodland
• few pests and toxic
• increases chaparral fuel levels

A few invaders of Canada

• Norway maple
• Acer platanoides
• Native of northern Europe
• Rapid grower
• Popular landscape plant
• invades native mixed forest
• alters forest floor ecology
• eradication programs underway in Toronto while city continues to plant it!

A few invaders of Canada

• English Ivy
• Hedera helix
• Coastal BC
• Forest floor and climber
• Smothers trees, branches break under the weight
• Poisonous, skin irritant

A few invaders of Canada

• Tatarian honeysuckle
• Lonicera tatarica
• Shrub to 2 m.
• Invasive species of mixed woodland
• Introduced late 1700s
• Russia, E. Europe
• Bird dispersed

...know the enemy
Some invasive characteristics

• Widespread native distributions
• Genetic variability – can adapt to range of conditions
• Similar native climatic conditions to those of invaded area
• Free from predation
• Effective seed dispersal mechanisms
• Association with humans
• Short juvenile periods
• Self-compatible
• High reproductive output
• Several reproductive strategies

Evaluation for invasiveness
(Weed Risk Assessment)

• Reichard (U. W.) flow chart or decision tree
• Pheloung (1995) scoresheet of 49 questions
• Cronk & Fuller compiled "invasive categories" 1-5
• All cover reproductive and morphological traits, history, ecological tolerances etc.
• Need for unbiased, botanically trained evaluators
• Dare I say
• ...taxonomists/systematists/morphologists?

Evaluating invasiveness decision tree
(2-7 questions)

Friend or Foe?

Towards a black list for Canada

The Canadian Botanical Conservation Network lists 84 invasive species. 11 are regarded as highly invasive (Scot’s Broom is not on this list)

Canadian Botanical Association

• Regional wildflower clubs, groups
  • Noxious Weed Working Group

New Canadian Plants
Commercial introductions

Over 85% of new Canadian cultivars are greenhouse crops / annuals (bedding plants, pot mums, poinsettias etc.)

Native selections gaining popularity

• Sterility (mostly in hybrids) is preferred
• Limits propagation to vegetative methods
  • maintains cultivar integrity
  • makes proprietary protection more effective

Sought-after characters

• Dwarf or compact plants
• Sterility
• Variegation
• Slow growers

New Canadian Plants
Commercial introductions

• "At risk" introductions are few in number – evaluation should not be burdensome
• Evaluation may have been completed elsewhere
• Evaluation is usually ongoing during crop production
• Few producers will knowingly release a highly invasive plant

Concerns

• Sexually reproductive species or cultivars released commercially without being evaluated for invasiveness
• Unreported introduction of wild species by plant lovers; often in small quantities and with questionable identification
• Reichard (2002): of noxious weeds intercepted at airports – 85% was in passengers’ baggage
• Clubs, botanical gardens, special collections, etc.
• Index semina (seed lists) and exchanges
• New uses of plants ("bio-based economy") e.g. bio-filters, site rehabilitation
• Poor public knowledge and appreciation for the situation

Workable solutions?
A white list?

• Australia and New Zealand have white lists
• U.S.A. Noxious Wed Act (1974) created a ‘Dirty List’ of plant injurious to agriculture; by 1993 it was 93 species (Lythrum was excluded). [750 sp. fit Reichard’s criteria for invasiveness]
• 1999 National Invasive Species Council (USA) were developing a Clean List
• By 2006 it will be refined to a realistic and fair phase-in process
• Codes of Conduct for botanical gardens initiated in 2001 at Missouri Botanical Garden (endorsed by the AABGA, 2002)

Towards a workable solution
A Canadian black list?

• Define invasive
• Establish a regional approach
• Don’t work at species level – work at cultivar level
• Assessment for potential invasiveness
• Don’t include agronomic weeds – pick a fight you can win!
• Stop "preaching to the converted"
• Involvement. Constructive communication
  • CFIA, nursery industry, land reclamation and roadside development departments, conservationists, botanists, societies, general public
• Taxonomic training
• Public education

References

The Public Garden 2002. (Journal of the American Association of Botanical Gardens and Arboreta: 17(4)

Randall, R. 2001. Garden Thugs, a national list of invasive and potentially invasive garden plants. Plant Protection Quarterly 16(4)

http://www.rbg.ca/cbcn/en/projects/invasives Can. Bot. Conserv. Network

Virtue, J. (2000) Weed Risk Assessment in Australia

Randall, R. Global compendium of weeds. www.agric.wa.go.au/progserv/plants/weeds/

Reichard, S. & P. White. 2001. Horticulture as a pathway of invasive plant introductions in the United States. Bioscience 51: 103-113

Canadian Weed Science Society www.cwss-scm.ca