Welcome to the wonderful world of weedy plants!
Weeds are superevolutionary products of human civilizations and activities - without humans there would be no weeds, just wild plants.
Wednesday, January 25, 2012
How to identify weed species
To be able to identify plants to a certain species, you will need a good flora, a handlens, and a little patience while you learn the botanical terminology that describes plant features (stipules, petiole, sepals, and things like that).
Some plant groups are a lot harder to identify than others, like the Polygonum genus in the rhubarb family Polygonaceae for example (see photo above). For them you will have to look at tiny hairs and glands through the handlens, but for many others it is enough to compare the photos in a photo flora. It depends. But to be sure, then you need a book (flora) that includes all the species in our area and usually something to magnify the plant with.
If you find something that looks unusual, you can always press and dry it and show it to a botanist later for confirmation. A photo is often helpful, but many species you can't tell apart from photos.
[photo by Vilseskogen, Flickr, Creative Commons]