It’s just a guess, but I’ll venture that the most widespread Philadelphia plant in bloom right now is this one, Ranunculus ficaria.
Around here it goes by the common name lesser celandine, although in other regions it’s known as pilewort or fig buttercup. It seems to be commonly confused with the name of a very well-behaved native plant, the marsh marigold, which is actually something completely different and much nicer.
As you might guess, lesser celandine is not a native plant. It’s a reproductive triple threat, multiplying by seeds, by underground tubers, and these little beige bulblets that rest on top of the ground to further colonize any undisturbed piece of ground. The bulblets give the plant its name, as they resemble tiny figs (latin ficaria.)
This plant is on a bunch of least wanted lists, from the USDA’s to Fairmount Park’s, and for good reason. Because of its vigor it overwhelms a number of native spring plants like trilliums, trout lilies, and spring beauties, all of which are becoming rare in the landscape.
The good news, relatively, is that this plant is an ephemeral. Within the next six weeks it will gain a couple of inches in height before turning beige and collapsing into mush, leaving bare patches of dirt as the only sign it was ever there in the first place.
Getting rid of it is a challenge, as pulling it seems to dislodge those little bulblets back onto the ground. Very carefully prying the plant out with a trowel, not shaking off any of the dirt, and getting it into a trashcan seems to be the only way to clean it out of garden beds. Like any weed that has a bulb, composting is going to do it a favor, not you. The bulbs will lie in wait in that nice rich medium until they are spread back onto a different part of the garden.
If you don’t already have this plant in your garden, exercise caution when accepting gifts of plants from friends or neighbors. The shiny leaves are a giveaway, but like all kinds of bad things (tetanus, sleeper cells, and carbon monoxide come to mind) even when you can’t see it, it could be there- yikes.