Eric
Carnivore
Nova Scotia is home to a lot of S.purpurea, so it is not surprising that also f.heterophylla is found there in several places. In one place more than just a few antho-free plants grow together with typically coloured plants. A report on these plants and their habitat was given by Sheridan and Scholl in ICPN 22 (1993) p.106.
I received some seed of cultivated plants 20 years ago. But all seedlings looked like typically coloured ssp.purpurea. I grew them to flowering size, selfed them and got antho-free plants as shown in the photo above. So the seed I got must have been open pollinated with another unknown purpurea, maybe even ssp.venosa. My plants mostly have a somewhat 'rectangular' orifice, i.e. the lip is not straight like in many other ssp.purpurea with a more 'D'-shaped orifice. But since there is a lot of variation within S.purpurea this is not of much significance. The flowering stem gets 45 cm tall.
My plants are probably not 100% pure, however, there are plants from this location in cultivation in the US, Canada and Europe which are unspoiled (but probably selfed a few times).