The humongous perennial pea that I showed off last week was relatively innocuous. These six are some of the more prolific weeds. Actually, except for the first two, these are some of the most aggressive and problematic weeds in this region. All are exotic, which means that they are not native. Some were imported intentionally. Some were more likely stowaways. All except for #2 were found right outside here. #2 was found closer to town.
1. Vetch was most likely imported intentionally as a cover crop, forage crop or both. Because I do not know which vetch this is, I do not know why it is here. This is neither of the two species of vetch that are native here. It is a polite and pretty weed that never seems to become much of problem. Consequently, not much is known about it, or how it affects the ecosystem. Most of us just let it do what it wants to because it improves the soil.
2. Queen Anne’s lace might have been imported intentionally because the young roots, young leaves and flowers are edible. It is, after all, a wild version of carrot. However, the small roots mature quickly and become too tough to eat, and often develop bad flavor. Furthermore, it is avoided because it it too easily confused with the extremely toxic poison hemlock! It can be a companion plant for attracting pollinators, but is mostly ignored.
3. Saint John’s wort was imported intentionally as a ground cover for landscapes, and escaped into the wild where it competes aggressively with native plants. It is toxic to grazing animals, so must be removed from where it appears in pastureland. Unfortunately, its wiry but tough stolons are extremely difficult to eradicate. This species is unavailable here, not just because it is invasive, but because it is so susceptible to rust. It never looks good.
4. Broom is one of the nastiest. Some believe it to be Scottish broom (which we call ‘Scotch broom’). Some believe it to be Spanish. Actually, it is most likely French. It doesn’t matter. It is terribly prolific and aggressive, with seed that remain viable and continue to germinate for many years after parent plants get removed. It was imported intentionally just because it is so pretty in bloom. So many of the worst weeds arrived here like that.
5. Himalayan blackberry, like Queen Anne’s lace, might have been imported intentionally because it produces something edible. It happens to makes decent blackberries. However, it is neither as reliable nor as productive as garden variety blackberries. Berries might be sparse and of inferior quality, and are very difficult to pick because the canes are so very wickedly thorny! Canes are extremely vigorous and aggressive, and difficult to kill!
6. Thistle was likely a stowaway. There is no realistic reason to have imported it. Nothing eats it. It is too wickedly spiny to handle. It does not work as a cover crop, although it does try to cover as much area as it can get its prolific seed into. There are other thistles that are more invasive, but none that are as mean as this one is with those formidable spines! I do not know for certain what species this is, but it is not one of the native thistles.
This is the link for Six on Saturday, for anyone else who would like to participate:
https://thepropagatorblog.wordpress.com/2017/09/18/six-on-saturday-a-participant-guide/
Tony Tomeo 
We have a similar vetch – which is very prolific and; if you let it, will cover a whole field and anything else growing on in, plus the Queen Anne’s Lace, of course. Your thistle looks very dangerous.
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That thistle is SERIOUSLY WICKED! It annoyed me that those I used to work with were not concerned about it. They would mow them down, and they would come right back and toss their seed. It is actually not as difficult to control as some other weeds, but it so often gets away with proliferating because no one will touch it.
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I’ll be darned. I’ve always assumed Queen Anne’s Lace to be native, but I just checked my big, fat book, and it’s not. I’m not even into my first cup of coffee, and I’ve learned something.
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I was always told that it was native, but I was also told that it was poison hemlock. I never did anything with it regardless. There were no horses that came into the areas where it grew, so I was not worried about anyone eating it. I happen to think that it is pretty, but would not want it around the home.
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Hypericum is one of bug bears, I am forever digging it up, which isn’t always easy. Some people love it though.
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The particular patch that provided the picture is not bad, probably because it gets no water. I know that it rusts before autumn, and looks shabby all through winter, but no one cares where it is. If it were possible, I would eliminate it because I know it tosses seed into Zayante Creek below. Many years ago, when people took horticulture more seriously, we used to mow it annually in landscape situations. I believe we let it look shabby through most of winter, and then mowed it just before it started growing again. It came back nicely uniform and neat. I never really liked it though. There are better ground covers to grow.
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All weeds here too, with St John’s Wort possibly the worst. It sometimes covers whole hillsides. And you’ve identified vetch for me. I have some in my garden.
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You have the same weeds?! Himalayan blackberry?! Oh my; I am sorry about that. It is a nasty one!
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I’m not surprised by the thistle turning up as it’s dispersed by the wind. In the Uk such ‘exotics’ would be called invasive species but saying that we have had such a culture of plants being introduced to the UK for 100s of years it’s difficult to know what is native.
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We know it as an invasive species too, or more specifically as an invasive exotic. We have not been importing them nearly as long here, but even here, there are a few that we are not certain about. The Hottentot fig (which some know as iceplant) supposedly came from Chile and Peru, but it might have actually been native here. There are also a few exotics that ignorant tree huggers want to be reclassified as natives just because they have been here for so long, like the various naturalized species of Eucalyptus.
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St. John’s Wort grows here in Texas, but it’s not invasive that I’m aware of. I’ve always liked it, but have never grown it.
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It doen’t rust?! That is not what I would expect. I would think that it would be more aggressive there, but also uglier because of rust.
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Fascinating blog Tony. That is not Scottish Broom as it has not got any red in they flower by the looks of it.
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No, it is only yellow. It is also too ‘leafy’. Nonetheless, that is how most of us know it. Actually, we know it at ‘Scotch’ broom, which I was told is not a proper adjective for something that is ‘Scottish’.
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Interesting that hypericum/St John’s Wort is considered a weed elsewhere – here it’s a popular garden plant, and though it can get quite big it doesn’t spread or self-seed.
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Big? That is likely a species that grows as a shrub, and does not spread aggressively by stolons. The species that is a ground cover form is the invasive one for us. Shrubby Saint John’s wort is not invasive, at least here.
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One man’s weed is another’s garden plant! I have a large shrub variety of hypericum, and a couple of smaller cultivars too, all bought like proper plants at a garden centre! That thistle does look wicked though…
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Even here, the shrubby ones are not invasive. They are just unpopular because they get so rusty. I dislike them because so-called ‘gardeners’ do not prune them properly. They always seem to look so bad.
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