Question
I have 50 sarracenia purpureas.... how can u tell the differerence between a sarracenia purpurea ssp. purpurea and a sarracenia purpurea ssp. venosa?

Answer
In general, purpurea ssp. purpurea has shinier, smoother pitchers, while purpurea ssp. venosa has slightly fuzzy pitchers.  If you load a photographs of two plants, one you believe is venosa and the other you believe is purpurea, then I can confirm them for you and you can use the experience to sort out your plants.  Make sure the photographs are clear, closeup images of your plants.  Avoid using a cell phone camera.  Use a high quality digital camera instead.

Otherwise, you could use books or photographs pulled from the web to help you identify your plants.

Good growing!
Jacob Farin