Rubus species

Wild blackberries can be found nearly anywhere with a roughly temperate climate, from Florida, to Washington state, to the UK, to Australia, although in some places are considered to be invasive species. There are many related species but they all have some basic similarities.

Blackberries generally have three, five, or seven leaves on each leaflet, like in this picture, and blue green foliage. Most wild blackberries have thorns, although this has been bred out of some domesticated types. The root systems are perennial, but the stems will sometimes freeze back during the winter and regrow in the spring.

These plants generally bloom from late spring to early summer. Their flowers are small and white, usually with five petals. The thorns and flowers are the closest similarities to their cousins, wild roses.

After blooming, the blackberries will change from green to red to black as they ripen.These berries are technically aggregate fruits, with many small fruits with one seed from each stamen in a multiple flower. The berries are only ripe once black, despite the raspberry appearance of the red ones.

Wild blackberries, unlike most domesticated blackberries, will ripen a few at a time, to keep animals returning over time, rather than getting full and wasting fruit. If you want enough to make a pie, you will have to either have access to a large number of bushes or go back every few days. I recommend using wild blackberries as a supplement to storebought ones, because they are smaller, seedier, and drier, but also cheap and more flavorful.

I got some of my info from Wikipedia, and the rest from my grandfather. (He has a degree on this, not just some foxfire book.)