Prohibited Plants Must be Destroyed

In 2010, the Alberta Government passed new legislation on weed control which includes two new lists of plants: "prohibited noxious" and "noxious". Plants designated as "prohibited noxious" are deemed to be nasty invaders and are illegal under the Alberta Weed Control Act. They must be eradicated if present in gardens, on farmland, or in any landscape in Alberta. They must not be sold at garden centres and nurseries and must not be brought in by cuttings, plants or seeds from outside of the province. Plants designated as "noxious" are considered less nasty but should not be purchased or planted or transplanted from other sites, and existing plantings should be removed. Plants on the "noxious" list may be elevated to the "prohibited" category by local authorities, so it is wise to check with your municipality.

Many of the plants on these lists are ornamentals known and loved by local gardeners. It will take an act of will for many of us to rid our gardens of these plants. But before getting out the garden spade, take care to note the specific plants on the lists. Some of these plants have species or cultivars that are NOT on the list. For example, while common barberry is now prohibited, barberry cultivars such as 'Rose Glow' are not. Similarly, common names can cause confusion. For example, purple loosestrife (Lythrum salicaria is prohibited while Alexander loosestrife (of the Lysimachia genus) is not.

An excellent source of information and assistance with plant identification is the Alberta Invasive Plants Council Web site.

The following plants are designated as prohibited noxious weeds in Alberta:

autumn olive — Elaeagnus umbellata balsam, Himalayan — Impatiens glandulifera barberry, common — Berberis vulgaris bartsia, red — Odontites vernus buckthorn, common — Rhamnus cathartica cinquefoil, sulphur — Potentilla recta crupina, common — Crupina vulgaris dyer's woad — Isatis tinctoria Eurasian water milfoil — Myriophyllum spicatum flowering rush — Butomus umbellatus garlic mustard — Alliaria petiolata goatgrass, jointed — Aegilops cylindrica hawkweed, meadow — Hieracium caespitosum hawkweed, mouse-ear — Hieracium pilosella hawkweed, orange — Hieracium aurantiacum hoary alyssum — Berteroa incana hogweed, giant — Heracleum mantegazzianum iris, pale yellow — Iris pseudacorus knapweed, bighead — Centaurea macrocephala knapweed, black — Centaurea nigra knapweed, brown — Centaurea jacea knapweed, diffuse — Centaurea diffusa

knapweed, hybrid — Centaurea × psammogena knapweed, meadow — Centaurea × moncktonii knapweed, Russian — Rhaponticum repens knapweed, spotted — Centaurea stoebe ssp. micranthos knapweed, squarrose — Centaurea virgata ssp. squarrosa knapweed, Tyrol — Centaurea nigrescens knotweed, giant — Fallopia sachalinensis knotweed, hybrid Japanese — Fallopia × bohemica knotweed, Japanese — Fallopia japonica loosestrife, purple — Lythrum salicaria medusahead — Taeniatherum caput-medusae nutsedge, yellow — Cyperus esculentus puncturevine — Tribulus terrestris ragwort, tansy — Jacobaea vulgaris rush skeletonweed — Chondrilla juncea saltcedar — Tamarix ramosissima saltlover — Halogeton glomeratus St John's-wort, common — Hypericum perforatum starthistle, yellow — Centaurea solstitialis tamarisk, Chinese — Tamarix chinensis

The following plants are designated as noxious weeds in Alberta:

baby's-breath, common — Gypsophila paniculata bellflower, creeping — Campanula rapunculoides bindweed, field — Convolvulus arvensis blueweed — Echium vulgare brome, downy — Bromus tectorum brome, Japanese — Bromus japonicus burdock, great — Arctium lappa burdock, lesser — Arctium minus burdock, woolly — Arctium tomentosum buttercup, tall — Ranunculus acris chamomile, scentless — Tripleurospermum inodorum clematis, yellow — Clematis tangutica cockle, white — Silene latifolia ssp. alba daisy, oxeye — Leucanthemum vulgare dame's rocket — Hesperis matronalis

henbane, black — Hyoscyamus niger hoary cress, globe-podded — Lepidium appelianum hoary cress, heart-podded — Lepidium draba hoary cress, lens-podded — Lepidium chalepense hound's-tongue — Cynoglossum officinale mullein, common — Verbascum thapsus pepper-grass, broad-leaved — Lepidium latifolium scabious, field — Knautia arvensis sow thistle, perennial — Sonchus arvensis spurge, leafy — Euphorbia esula tansy, common — Tanacetum vulgare thistle, Canada — Cirsium arvense toadflax, Dalmatian — Linaria dalmatica toadflax, yellow — Linaria vulgaris