pernicious weeds

[animartco]

It is a good trend to want to grow wildflowers in your garden, but please spare a thought for your neighbours, and -where seeds are windblown, for the countryside as a whole.
There are two kinds of wildflowers, the common weeds and the rarities. It is the rarities that we need to demand from responsible seed organizations, and fill our gardens with. There is a lot of work involved in this, and the plants are often difficult to grow and take a lot of nowhow, but boy is it rewarding to be able to 'return to the wild' plants that are rapidly approaching extinction!
On the other hand, filling your garden with stands of common plants that can seed or greep outside your garden is threatening the existence of the rare plants that still exist in your area. All plants have to compete for light and sustenance, and if you are releasing seeds from a load of very successful weeds then you will be LOWERING the biodiversity of your area.
Plants that should never be deliberately grown are brambles common dock bindweed ragwort, creeping and spearplume thistle, ground elder, and horsetail. These are natives. There are also of course a lot of introduced species that should never be grown. Remember, gardens, with their rich soil can make a species even more of a nuisance, by improving its genes.

[aeshna5]

Ground Elder isn't native- it was introduced by the Romans!

Many fairly common wildflowers make good garden plants- such as Field Scabious, knapweeds, etc.

I can't see too many people deliberately planting docks, Creeping Thistle, but these plants are already very common through most of the country. Anyone tolerating them in the garden in a wild area isn't going to make much of a difference given their ubiquity.

Brambles are an excellent wildlife habitat, but agree they may need controlling in certain situations as could be said for nettles, etc.

[animartco]

Hi Aeshna,
I was chatting to a friend this morning who was complaining about the ground elder coming through from next door. It is a terrible weed, but some people on the site have been praising it. Ditto the ragwort which is a killer. I wonder if anyone has studied how many bats are killed by eating cinnabar moths? Increasingly we have to be good managers. A few bats or songbirds killed fifty years ago didn't matter too much. Now they are so threatened by us, we have to try hard to think about their safety.

[aeshna5]

I doubt many Cinnabar Moths are caught by bats as they are a day flying species. I'm guessing that if they did catch one they may well spit it out as it's distasteful. Though still fairly common, Cinnabars are actually declining.

Ragwort as a native species has been here for millenia + very important food source for many invertebrates. I appreciate the need for control around grazing stock, though the plant is mainly a problem in dried hay- there's already been a very detailed thread on this citing various research if you care to look it up.

Agree Ground Elder can be a curse to gardeners (also called Goutweed as it was used for this condition), but I don't think it's particularly a major ecological problem. I've seen a variegated form of this plant for sale in garden centres.

[davidbr]

Personally I have a special interest in alien plants, so I'd always encourage anyone re-seeding their road verge/motorway/front garden to buy their grass seed from as faraway a country as possible

The vast majority of introductions don't do any harm; most struggle to survive our weather conditions, that's why they're so unusual and often so hard to find. The ones that do, only survive because they find a niche to exploit. Anyway, most of the plants that people consider to be natives were probably introduced many years ago

[Cotham Marble]

Originally Posted by animartco

Ditto the ragwort which is a killer. I wonder if anyone has studied how many bats are killed by eating cinnabar moths? Increasingly we have to be good managers. A few bats or songbirds killed fifty years ago didn't matter too much. Now they are so threatened by us, we have to try hard to think about their safety.

I hate to labour this point but these ideas about 'bad plants' can easily become accepted popular notions with significantly unhelpful results. I refer you again to the earlier thread Ragwort: is it illegal - specifically to the post at the top page 3 which details the work of Professor M.J. Crawley Professor Mick Crawley -- Department of Biological Sciences

As Aeshana points out Cinnabar moths are daytime flyers - a fact which is fundamental to the adaptation of their larvae absorbing toxins from ragwort. Both larvae and adult are brightly coloured as an alert to predators - a quality that is only significant to daylight hunters. Further there is no benefit to a prey species having toxicity as a ward against predation if the prey species ends up being killed before the predator is disuaded from attempting to eat the prey, while death of the predator will only be of benefit in some very limited environmental circumstances. In most cases what the prey species benefits from is a predator 'learning' that the prey is distasteful. As far as I can tell although there are studies on the toxicity of Cinnabar moth larvae, there is no data that says that the adults would be lethal to any likely predator. The most advantageous adaptation would be if the adult retained enough toxin from its larval stage to make it taste/smell bad and so inhibit a predator causing fatal damaged.

Cinnabar moth larvae are a natural control on Ragwort, by allowing Cinnabar moths to take advantage of urban and urban fringe grown Ragwort, an increased population of the moth can recolonise rural hay meadows and horse pasture. This is a far more useful scenario than making Ragwort a notionally 'evil' species which has to be rigourously controlled.

For more on ragwort hysteria: Ragwort - Is it as bad as you think?

For anyone who has unwanted ground elder - tagettes produce a chemical which inhibits ground elder growth. After digging out ground elder, plant tagettes for one season, this will impede ground elder re-growth.

CM

[Susie]

Originally Posted by animartco

There are two kinds of wildflowers, the common weeds and the rarities. It is the rarities that we need to demand from responsible seed organizations, and fill our gardens with. There is a lot of work involved in this, and the plants are often difficult to grow and take a lot of nowhow, but boy is it rewarding to be able to 'return to the wild' plants that are rapidly approaching extinction!

Not quite sure what you mean by this? Do you mean that you grow rare plants in your garden and then transplant them into the wild or that you let the wind disperse the seeds for you? Or perhaps you mean something else and I have misunderstood completely.

[animartco]

Oh Aeshna5 you do love to argue. So do I! The Romans introduced practically all our wildflowers didn't they? I'll tell you something funny about those variegated ground elder. My neighbour bought one. I said "Isn't that ground elder!"
"Yes" she said "But it's pretty. It's a special variegated cultivar." Then she wondered, a year later why she suddenly had a garden full of green ground elder smothering everything!!! Never expect garden merchants to be responsible citizens! (There had been NO groud elder in the garden before she introduced it.)
field scabious and knapweed are not particularly rare but neither are they any sort of nuisance. Plants like these and nettle bell flower do not run riot over neighbouring properties and fields, though I still say with such diminishing habitat as we have in Britain it is a good idea to try to get some of the rarer species into our gardens. The problem here is of course finding them. You'd need to order them through a responsible body like the RHS

[Meta menardi]

I sadly fear that if I was to remove all the Ground Elder in my garden, the house would be teetering on the edge of a mighty crater.

I didn't do it, it was there when we bought the place, but it can be gardened around.

[animartco]

Originally Posted by Susie

Not quite sure what you mean by this? Do you mean that you grow rare plants in your garden and then transplant them into the wild or that you let the wind disperse the seeds for you? Or perhaps you mean something else and I have misunderstood completely.

Yes. If people collect seeds for their gardens why not also take them out again and scatter them? Or what most people here do is plant up the verge oppositetheir house and let them spread from there.