Photo #1, I believe, is a juvenile form of Rudbeckia (Black Eyed Susan). If the leaves and stems are hairy, that is. These are shallowly rooted and are easily controlled by hand pulling. They are vigorous reseeders and could have blown in by the wind from other flower beds or the neighbors flower beds. Photo #2 check their stems for being square and when the leaves are crushed they'll have a minty smell. If that appraisal proves correct they have to be hand dug and try to get as may roots as possible. Like the dandelion this one comes back from the roots quite easily. Please contact me for further questions regarding these plants. Thank you for using the Ask an Expert System.
Photo #1 - The leaves and stems are not hairy. I have juvenile forms of Rudbeckia, and I pull them, so I know what those are. Photo #2 - Stems are square but the leaves are not minty, they smell like any weed when the leaves are crushed.
Bear with me please. The plant with the square stem is from the mint family even though it doesn't smell minty. It should be treated as very invasive. I'm still working on the other plant. Hopefully I'll have an answer tomorrow when I have my office resources available. Thank you for your patience.
I put in a butterfly garden 2 years ago and I planted Blue Vervain. I noticed the leaves looked like my Blue Vervain plant put I pulled the weeds out last year before they got tall. This year, I didn't have time to pull them so they took over and now some are starting to bloom. They are Blue Vervain, not a weed or part of the mint family. I have a Wildflower of Michigan book and it says it is often confused with the mint family. What the book doesn't say, or any article I read, that is reseeds very quickly! I have 4 plants and they will be pulled out today! Please keep working on the other "weed". Thank you!
Heliopsis helianthoides is a member of the multi-flowered sunflower family. It is not known as a weed as well. I have this in my own garden. I haven't known it as an invasive because I have so many other problem plants but the leaves are very similar close to being identical to the leaves that your pictures show. Persistent pulling of the problem plants should help cure the invasive situation. I hope that this helps you. Thank you once again for using our service.