I admire the experts who seem to know everything about plants and can identify them in all stages. But I do enjoy the sleuthing required when I find mystery plants in my yard. Like Z's weed, I've enjoyed the bounty of volunteers that crop up in the middle of nowhere.
Last year I transplanted anything that looked a little different, hoping that I might get lucky. I was rewarded for my kindness this year with a sea of blue forget-me-nots complemented by cheery yellow poppies. (We won't dwell on the saga of the yellow hawkweed I nurtured to unforgettable heights before its ultimate identification!)
Forget-me-nots and poppies spread quickly one year after transplanting volunteers from the lawn
Another mystery plant that multiplied by itself this year is the dogberry, or timberberry. I was quite curious about the difference in color between individual plants before I read that the variegated specimens are likely taking over roots of other plants, as it is semi-parasitic. Since the berry is reportedly not very tasty, this may be one volunteer I'll send packing!