While S. rosea var. luteola and S. purpurea ssp. purpurea f. heterophylla are well known amongst collectors, S. purpurea ssp. venosa 'Antho-free' is almost unheard of. Very few people in the world have this plant.
Interestingly enough, this is a man-made plant, and my understanding is there has never been an AF S. purpurea venosa discovered in the wild to this day. Another peculiar aspect of these all green venosas is that they sometimes have folded hoods just like montanas. Under optimal conditions, the plant turns bright yellow, and sometimes the traps get bleached out from the sun and have almost a slight white tinge to them. There has been some speculation as to whether these are montanas, but I don't have enough info to support or deny such a hypothesis. What I do know for sure is that these plants are down right amazing!!!
S. purpurea ssp. venosa Antho-free, photos taken 8/4/13: