Sorry guys, Lou's post finally provoked a response from me, and admittedly, a skew one ! He said: but there may well be some species with a history of invasive behavior that should legitimately be banned even in small lots of seeds. Think Oxalis. I could spend hours every day cleaning Oxalis out of my pots and they would still return. They must have started from only a few seeds. Some plants do deserve to be banned. This is nonsense. One cannot make a rule affecting a whole genus because of a skew understanding of the genus as a whole or because of the presence of an unruly few, an idea which I think has been suggested in previous posts. One does not judge a whole family by glaring down on the blacksheep, each and everyone to his own merrit, please! In defence of Oxalis The genus Oxalis have a few (my guess is less than 10 -please correct me) possible invasive BULBOUS species, and disregarding the 250 + low or zero risk species is not making much sense. And probably the one Lou is trying to eradicate is one of the Oxalis corniculata group (smallish creeping and crawling plant with small yellow flowers). It does not have a bulb, it can self pollinate (very few Oxalis do, in fact it's only the "weedy" or shrubby species which does), and its a native American spread right across the globe. In my experience (that is, my garden) all invasive Oxalis are american species (I even suffer with two forms of O corniculata, and you are bound to get O. latifolia now and then with a nursery bought plant), so you (USA) are still stuck with them, even if you ban all others !! Admittedly, Oxalis pes-caprae has taken foothold in many parts of the world, but IT STILL DOES NOT SET SEED, and can be perfectly contained in a pot if you realize how it spreads. Old potting soil needs to be sterilized or soaked with systemic weedkiller before dumped in the garden or refuse heap in order to kill all bulbills. And most of the other bulbous species have such strict pollination rules that even by careful pollination might not yield any seeds (once again, there are exceptions). Some species can produce copious amounts of axil bulbs, and some of these (eg. those of O pocockiae) are very light and can be carried away by water to a nearby area. Once again, understanding the species will allow you to make right decisions, and the axil bulbs can be easily destroyed when still unripe. How many of these axial bulbs actually grows into maturity is still a good question. So to make a rule about a genus which have a few (my guess is less than 10) possible invasive bulbous species, and disregard the 250 + low or zero risk species is not making much sense. For some point of reference: I have currently more than 500 pots with Oxalis, featuring some 380 species and forms Last year I planted 5 species in my general garden/rockery. Only one remain. This year I have tried about 30 species. Less than 10 grew. I'll see next year how many of these survived. I have been a dedicated Oxalophile for more than six years In my collection the only Oxalis that set seed are: O purpurea, if I deliberately pollinate them O obtusa, once again with deliberate pollination O fabifolia - I have seven colour forms growing in adjacent pots. They do seem to propagate from the bulbs that well. The seed last about 36 hours - they have no endosperm. So if I do not pick them up (they are about 2mm in diameter - and bright green) and place them in a suitable possition and pot with increased watering, they do not survive. O haedulipes - This one sets seed freely, and I am decreasing my collection of this species to contain only one stylar form, which will prohibit seed formation. In defence of this species I should add that I live right in the middle of it's natural area of habitat (thus right temperature, right pollinator, etc.), and I had about 15 different clones of it.