I don't grow them so I have no personal experience, but they are an ephemeral, meaning that they will pop up early before much else is out yet partly because this is the only sun they will see for the year as the trees will soon leaf out. Then they go dormant till next spring. This being the case, I do not think they can do much damage to an eco system.

I will stand corrected if others have different information.

Helen.

I have tried to grow White Dogtooth violets/ Trout lily (Erythronium albidum) and they are very slow growing. They failed to come back this year, so I think they died or were eaten by wildlife. They do spread to form colonies but it takes a long time for them to grow to a significant size. I think that your friend's woods must be perfect growing conditions for them and they have had a long time to spread. Or perhaps they have a mutated trout lily that has become invasive!

Thanks for the posts. I feel relieved now and will try to collect some bulbs next time I visit.
Their woods contained what appeared to be millions of these plants. I'll have to see what it looks like in summer. Hopefully they disappear at that time.

They are extremely precious! I have many in my gardens - BUT only 5 or 6 actually bloom (and yes trout lily and dog-toothed violet are the same) The bulbs have to be planted at exactly the correct depth and have exactly the right light to bloom. If you disturb them (dig them up) it'll take a couple years before you'll know if you got them right in re-planting. If they only pop up one leaf consistently they'll never bloom. The only reason any of mine ever did (the person who planted them, none of them bloomed) was because I didn't realize where they were when I went in to plant some other things and they got shifted just a bit - they seemed to have liked where they wound up! Only spot they bloom! They are totally native here and I find them totally delightful. Be patient with them, but I think you'll never regret transplanting them into your garden. They prefer light in spring with heavy dappling in summer. All the ones in total shade are the ones that aren't blooming :)

-Marie

I grew up in LeSueur, and later in Owatonna, MN .We lived in an oak woods near a creek. dogtooth violets were everywhere. Despite that, they were not a problem, as they are small and go dormant after blooming in early spring. they were in our lawn under the trees, but they tolerated being mowed over and still returned every year.