For those Star Trek fans out there: “They’re invasive Jim, but not as we know it”!
First, lets talk about the elephant in the room. I say “Cot-own-e-asters” you say “Cot-on-easters”, others may say it differently but it really doesn’t matter! We all know what we’re talking about – those small-leaved shrubs much loved by developers of business parks, supermarkets and garages (and so much more). Loved because they are hardy plants that cover the ground (suppress undesirable weeds) and are easy to maintain. But actually we need to be careful not to make too many generalisations.
Be careful – some Cotoneasters are invasive!
This family is remarkably diverse in form and habit with over 100 species cultivated in the UK. Some are native or naturalised European species (closely related to Hawthorn, Rowan and Pyracanthus) but the majority are non-native and, here’s where we get interested, some of these are invasive and listed in Schedule 9 Part II of the Wildlife & Countryside Act 1981. This means that when our members are conducting surveys for invasive weeds they need to be able to spot these and avoid confusing them with those that are benign garden or landscaping ornamentals! Is it Friend or Foe?
Why is this important? Well, we should applaud this particular family of non-natives for their amenity value AND for their flowers (in my garden at least, absolute the best bee magnets ever!) AND for their fruits which are a much loved and valuable food source for winter thrushes (and wood pigeons, personal obs.). But this week we became aware of a new and thought provoking benefit when we saw the headline “Pollution catching ‘super plant’ ideal for busy roads”.
It turns out that the RHS have conducted research in to C. franchetii (Hairy-leaved cotoneaster) which when compared with other hedging plants absorbed 20% more pollution (particulates) next to busy roads – equivalent to 100 miles of exhaust fumes per metre of hedge per week! “Hedge your bets with ‘super plant’ to fight air pollution”. Nectar. Fruit. Now air purifier!?
Can you identify all Cotoneasters?
So it’s really important to know which Cotoneaster you are looking at. Sorting the good guys from the bad is no easy task, but the PCA has taken the initiative in providing training on invasive weed identification and this includes Cotoneasters. Not all of them of course but at least enough to be able to use the botanical keys and spot those on Schedule 9.
So, now you know why its important to know your Himalayan (C. simonsii) from your Cranberry (C. apiculatus), your Small-leaved (C. microphyllus) from your Tree (C. frigidus) and your Hollyberry (C. bullatus) from your Showy (C. multiflorus) cotoneaster!
We hope this leads to a better appreciation of the benefits of some of our alien friends whilst also ensuring that your clients are made aware when necessary, that they may need to take control action to prevent the spread of a Schedule 9 species. Survey reports which say “you’ve got cotoneaster” without saying which species, will definitely lose you a mark on your next member audit! You have been warned…
Editorial note: Everything you’ve ever wanted to know about Cotoneaster, and more besides, can be found in our “Practical Management of Invasive Non-Native Weeds in Britain and Ireland”.
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