Since we all suffer through months and months of grey and brown in the landscape, it’s understandable to welcome any and all green when spring finally arrives.
But not all plant material should be embraced. There are all kinds of plants on the invasive list — and even more on the noxious list. And please, let’s not have the dandelion conversation any more. Sure, swaths of dandelions look horrid on boulevards and in lawns, but they are easy enough to control if the grass is well maintained and fertilized regularly. You can always ‘spot-rid’ your lawn of these beasts by inserting a knitting needle into its heart and then pour boiling water into the hole. It takes time, but it does work. End of discussion.
Far more destructive to natural areas, rangelands and watersheds are thugs, the likes of purple loosestrife and oxeye daisy. The former, referred to as “the beautiful killer,” takes over ponds, irrigation canals and marshes. A mature plant can produce 2.5 million seeds! So nasty is this weed, it is against the law to grow it under the Alberta Weed Control Act. The latter, the oxeye daisy, is unpalatable to grazing stock and single plants will very quickly become large patches. Some cultivars sold as Shasta Daisy are in fact oxeye daisy and the seeds are often found in wildflower mixes. Contents of these mixes are rarely listed accurately and may contain seeds of non-native, aggressive plant species legislated as invasive. Avoid wildflower mixes at all costs unless the mix clearly labels the plant’s scientific names.
Other unwelcome plants include:
Yellow clematis: Sure, the silky long tufts and yellow pendant flowers are pretty, but this spreading vine plant is moving into mountain parks and once established, it’s aggressive indeed and will displace native flora thereby increasing the risk of fire.
Creeping bellflower: Again, it’s pretty enough, but if you have this beast growing in your garden, my sympathies. It reproduces by seeds (each plant can produce more than 15,000 seeds) and slender-almost hairlike rhizomes and tuberous roots. The rhizomes can travel under fences, sidewalks and driveways. It thrives in sun or shade and even withstands drought conditions. It’s become resistant to some herbicides so it is very difficult to get rid of.
Tamarisk (a.k.a. Summer Glow, Salt Cedar or Pink Cascade): Now this is one nasty species. The deciduous shrub grows along ponds, creeks and rivers. The shrub consumes as much as 750 litres of water a day. And it gets worse. It’s scale-like leaves actually concentrate salt from groundwater and release same back into the soil with its leaf litter. Increased salinity (salt) in the soil makes it extremely difficult for other native plants to survive. It grows three to four metres in a single season and produces 600,000 seeds annually. Even severed stems will root readily.
And I saved the worst for last. Japanese knotweed: It’s on the Alberta watch list and thank goodness it is not here — yet. In its native Japanese volcanic landscape, the climate and regular deposits of ash would keep knotweed plants small. But when the plant was imported to Britain in 1850, disaster soon followed. It can grow up to 20 centimetres every day and will even grow through concrete. Its roots can go three metres deep. It is estimated knotweed costs the U.K. economy more than $200 million US per year for treatment and in home devaluations. In some parts of Scotland, you cannot get a mortgage on a property for two years if knotweed is in — or anywhere near your yard.
Earlier this year, a man who murdered his wife before killing himself cited the weed that had blighted their West Midlands home as the cause for his mental distress.
In a suicide note, lab technician Kenneth McRae, 52, wrote: “I believe I was not an evil man, until the balance of my mind was disturbed by the fact there is a patch of Japanese Knotweed which has been growing over our boundary fence on the Rowley Regis Golf Course.”
Dandelions seem rather tame by comparison, wouldn’t you agree?