A dear friend and I went to see her mother's garden. Anne said that one bed was ever so beautiful, just filled with yellow flowers that her mother had never planted. She commented that every spring there seemed to be more. I looked and there it was. Everywhere. The flowers were shiny and resembled buttercups. The leaves were heart shaped and close to the ground. It was lesser celandine. I grimaced. This is an ephemeral ground cover which means that after the plant blooms the entire plant seems to disappear. So what's the problem? The tubers or under ground stems of lesser celandine wait underground until late in the winter when they gradually wake up, send up new leaves, and begin the cycle all over again. This plant also reproduces by achenes which are tiny dry, one-seeded fruits that are spread by birds. Next year you will see more of these plants. Their rosettes will be everywhere... in your gardens, your neighbors' gardens, in your perennial gardens, in your grass. So what? Who cares? They disappear don't they?
Lesser celandine is an exotic introduced plant that competes with native species. How does it do this? Lesser celandine completes its life cycle early and thus shades out and steals nutrients from native species and from plants trying to get started in your garden in the spring. It does this by getting there first, before bloodroot, trout lily, Dutchman's breeches, and other ephemerals emerge. You may be saying "Well I don't have a native species garden"? The problem is birds spread the seeds from your garden into forests and other uncultivated places. Lesser celandine will crowd out the native plants. Please dig up lesser celandine. I know this plant is attractive but good gardeners must realize that no garden lives in isolation from the rest of the world. By the way the flowers and leaves of lesser celandine make lovely pressed plant specimens.
Another weed to take care of now is cleavers also called grip-grass or catchweed, Galium aparine.. This is an annual and is actually a native species but I know you don't want it in your garden. The leaves grow in whorls. Cleavers produces tiny white flowers from May through July. Dig this plant out whenever you see it . Don't pull it out because each remaining piece will grow into a new plant! Neglect this task now and you will find cleavers growing onto and through many of your annuals and perennials. The vine weighs down the plants and steals nutrients from the plants.
What about the dandelions in your gardens? If you can be sure that no pesticides have been used you most certainly can eat the young leaves or make wine from the flowers. Dandelions were brought to the New World as a vegetable and escaped from gardens into the wild. We don't like them because dandelions are so very successful. I can't think of another weed that has a digging tool named after it! If you dig out your dandelions be sure to get the entire root because any remaining part will regenerate.