While it was busy naturalizing in Australia, South Africa and southern South America, the California poppy was getting forced out of parts of its own native range by more aggressive exotic plants that were also busy getting naturalized. Technically, any plant that is not native is exotic. Any exotic plant that becomes naturalized in a foreign environment is able to proliferate without any help, as if it were native. Naturalized exotic plants that get too aggressive become invasive weeds.
Weeds are plants where they are not wanted. This is a very broad definition that includes plants ranging from simple little dandelions in urban lawns to humongous bluegum eucalyptus in forests. Naturalized exotic weeds can be much more problematic than weeds that can only proliferate where they get watered in gardens and landscapes, because they can get established where they are not expected.
Water hyacinth that clogs the Sacramento and San Joaquin River Delta is not often a problem in terrestrial landscapes. However, giant reed, pampas grass, Acacia dealbata and blackberry brambles can infest home gardens just as easily as they infest wild lands. Because they do not need to be watered, they can get established and grow quite large in unused parts of the garden before anyone notices.
Many naturalized weeds somehow seem to much more aggressive and problematic than even the most prolific of native plants. Even the common native lupines are relatively docile compared to annual oat grass. Native blackberry may seem impossible to eradicate, but is actually neither as persistent nor as unpleasant to handle as the exotic Siberian blackberry!
Young weeds are easiest to pull now while the soil is still evenly damp, and young roots are only beginning to disperse. They will be more difficult to pull after roots are dispersed and soil hardens. Tree weeds and large perennial weeds that were cut down last year instead of pulled will likely need to be dug. Bermuda grass is a relatively low perennial grass that always seems to be difficult to dig. Mowing or cutting down annual grass weeds with a weed whacker will not eliminate them, but limits the development and dispersion of seed for the next generation. Burclover, sowthistle, bindweed, purslane, spurge and the various oxalis are some of the other common weeds that really get going this time of year.
Tony Tomeo 
I am sure you are like me and have weeds 365 days of the year. My nemesis this year is oxalis. Animals, bugs and a deep freeze won’t kill them.
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Oh, there are so many species of oxalis! It baffles me that some species are grown as ornamentals!
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Please, don’t remind me. Sad to hear about CA poppy being displaced.
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Poppies still grow wild, but not like they used to. I remember the lower parts of the hills south of San Jose were orange during bloom. My Pa remembers more of those same hills in orange. Nowadays, there is no orange remaining, partly because the poppies are gone, and partly because the hills are covered in homes.
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This plant, American Pokeweed has turned up here, in SW France, quite an amazing plant, another great Flower Essence!
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Oh my! This is another one that has potential to be toxic as anything more than an essence. It amazes me that people bother eating the juvenile shoots. There are plenty of other greens available that are not so potentially toxic if harvested too late. I use this plant only for ink. What is the essence for?
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This one helps those without a belief system to understand there is a need for one, it encourages spiritual faith. 😁🙏
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If it were more than an essence, it could accomplish that by providing a near death experience. What an interesting essence though. The plant is a weird one. I mean, although I work with many species, this one is very different and . . . odd, perhaps because, to me, it is unfamiliar.
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I agree it is a very odd plant, I was so intrigued the first time I saw it…we have only had a couple of them, and they are really quite big if left to mature.
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Because it is a new weed here, I still prefer to cut it down before it disperses seed. Unfortunately, that will do nothing to limit its dispersion now that it is already established here. In my own garden, I will likely grow a single specimen just for the berries, but will try to collect the berries as they ripen, and not let the plant get too big.
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