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Native Plant Primer

By Patsy Cotterill


ENPS has acquired several new members in recent months and it has been suggested that a primer on native plants and native plant gardening might benefit newcomers to this field of interest and endeavour. So here goes.


Natives vs. Non-natives


Native plants, that is, plants native to a particular country, area or place, are usually assumed to be those that have evolved in that place or else migrated there naturally in geologic time.


This is in contrast to species that are not native to the place in question, but have come from elsewhere, usually carried by human agency, or have been deliberately bred and cultivated by humans. If these non-native species have become established in the new place and now grow independently without further introduction or cultivation, they are said to be naturalized, by analogy with citizens who adopt a foreign country as their new home.


Note that this definition differs from the one commonly used these days – see the article on Naturalization in this issue.


Another word you may see in connection with plant origins – or indeed disease organisms – is endemic, referring to species that occur as native to one place or region only. Endemics have high conservation value. In Alberta, although we have our share of rare plants, we have few endemics to worry about; a very large number of our species occur all across Canada in the appropriate habitats, and/or we share some western ones with B.C. Most native plants live in natural communities, such as woodlands, grasslands, peatlands, wetlands and river or stream sides.


Non-natives, Weeds and Invasives

Most of our non-native plants have been introduced from temperate countries through human activities such as international trade and the development of agriculture. They have found our Canadian climate and environment to their liking once human settlement has created the disturbed, anthropogenic habitats they had become used to in their home countries.


Many of the species listed as Prohibited Noxious or Noxious Weeds (with varying implications for removal) have significance as problems for agriculture, reduced crop production and lost revenue; other species in the built-up areas of cities are merely unpleasant or untidy to look at, in other words a nuisance; yet others (introduced plants, usually weeds and often invasives), penetrate natural plant communities and reduce biodiversity and ecosystem function.


Brome grasses provide an interesting example. In the drier south, an annual brome, downy brome or cheatgrass, causes havoc in rangeland, outcompeting native grasses, and here in Central Parkland, perennial non-native smooth brome grass, originally introduced for forage, is the grass you see everywhere, from roadsides and fields to forests.


Another ubiquitous grass, also introduced with settlement, is Kentucky bluegrass. Both grasses are considered naturalized and fall below the purview of the provincial Weed Act, although both are responsible for huge loss of native groundcover. In the grassland habitats of the Parkland and farther south they replace the native plains rough fescue grass which simply cannot regenerate after it has been removed by the plough, and other native grasses.

Common dandelion, Taraxacum officinale, grows without cultivation (that is, has become naturalized) in lawns, fields and waste places, but is a non-native and invasive weed from Eurasia. Photos P. Cotterill
Common dandelion, Taraxacum officinale, grows without cultivation (that is, has become naturalized) in lawns, fields and waste places, but is a non-native and invasive weed from Eurasia. Photos P. Cotterill

A few invasives do, however, warrant control under the Weed Act, such as garlic mustard, which invades forests, particularly in eastern Canada, purple loosestrife, which invades wetlands, and Himalayan balsam, likewise a moist ground/riparian species.


ENPS’ Mission

Because settlement and urban expansion have meant both the loss of native species and a great increase in the volume of horticultural plants in civic beds and residential gardens, the ENPS has sought to redress the balance a fraction by growing native plants and promoting native plant gardening to others. We have salvaged native plants from within the city and its environs that were going to be destroyed by development, and now we mostly grow native plants from wild-collected or garden-grown seed.


Much confusion exists in the public mind about weeds and wild plants. Some people regard all non-horticultural species (i.e., growing wild) as weeds, while others define, highly anthropocentrically, a weed as simply a plant that it is growing where it is not wanted. Generally, the ENPS distinguishes between native (as defined above) and non-native plants (introduced plants (weeds) that may also be invasive, and horticultural varieties of native plants). Weeds usually have a particular set of characteristics: they are fast-growing and quick to reproduce, either by seed or vegetatively or both, which makes them well suited to colonize open, disturbed ground. This has implications for naturalization in urban environments (see the Naturalization article).

Golden bean, Thermopsis rhombifolia, is an example of a native legume species that grows in prairie. It was of great significance to Indigenous Plains peoples as its flowering indicated that the bison were well fed enough to hunt.
Golden bean, Thermopsis rhombifolia, is an example of a native legume species that grows in prairie. It was of great significance to Indigenous Plains peoples as its flowering indicated that the bison were well fed enough to hunt.

The Home-grown National Park® Idea

Doug Tallamy, an entomologist and ecologist at the University of Delaware in the U.S., has conceived the idea of a Homegrown National Park®, in which citizens across North America grow natives on private and public property to create a vast network of native vegetation that feeds declining insects which in turn feed declining numbers of birds. They are fortunate in the eastern U.S. in having oaks which represent complete 8 ecosystems and are easy to plant, but we in the West should also try to emulate the Homegrown National Park® idea by establishing connected natural spaces. Even in a city, some form of natural connectivity is possible. Plants can move to a limited extent, by their seeds, rhizomes and suckers, and through the agency of animals, insects, birds and mammals, including humans, so even isolated green spaces can be connected. ENPS is a big fan of Tallamy’s ideas!


Gardening with Native Plants


As stated, ENPS encourages the use of native plants in gardening, and we recommend that you garden with native plants in the same way as with horticultural ones.


It is often said that natives are easy to grow because they are adapted to local climate and soils. While this may be true, we do not necessarily understand their growing and survival requirements. Traditionally, nature has grown native plants, and we weren’t around when some of these ancient plant communities were formed. By contrast, we have been growing commercial species for centuries for food, medicine and other resources, and in many cases have bred them to germinate easily and can be grown reliably. However, countries all over the world are learning how to grow their native species.


ENPS’ experience has been mostly limited to herbaceous species over the last 20 years, but what we know appears in some of our literature on the website and in our past WN newsletters. Across the globe and even in Alberta researchers are now figuring out how to grow plants that are on the brink of extinction or are important components of ecosystems that have been destroyed by human pressures.


In my opinion, native plant gardeners in the city should apply the same principles of landscaping to natives as they would to regular, horticultural species: plant low species in front of taller ones, do mass plantings of a single species for effect and to create weed-excluding ground cover, be aware of flowering times for a continuous display of colour, and so on. Species that have attractive fruits as well as flowers should also be considered, such as three-flowered avens, and meadow blazingstar, as well as the berry-bearing shrubs such as red-osier dogwood, saskatoon, and roses. Indeed, a variety of native shrubs are available from nurseries or can be grown more speedily from cuttings to provide foundation plantings of natives.


If you are raising natives from seed we recommend growing them in flats or pots nursery-style, providing the same kind of watering care, and potting them up and doing the final transplanting when they are robust enough to go into the ground. (Fertilizer should not be necessary if the soil is good enough to support growth.) See our website Plant Index pages for more details.


Native plants spread, die back, and sometimes suffer from insect infestation and disease in the same way as horticultural species do, so management is necessary. However, seed heads should be left on plants to provide food for animal life (they often look very attractive in the winter when covered by hoar frost or snow) or for collection and propagation, and litter provides insulating winter shelter for insects and other wildlife. Growing natives can present a learning curve but the conservation motive is a strong one until the rewards kick in – a garden of healthy native plants, insects and birds.


ENPS is Interested in Feedback


Popular interest in promoting pollinators is high, and we in ENPS would like to have more precise knowledge of which pollinators use which native plants. More generally, we are interested in learning about the growing experiences from our native growers out there. To provide feedback, please contact us at info@enps.ca.


Reference: https://edmonton.ca/programs_services/pests/weed-identification-advice

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