Here's how to do this:
Create a plant, and give it a common name that should apply to all plants in that gneus.
Then specify the genus and if you want it to apply to all plants, regardless of species, then leave the species blank.
Then leave the cultivar blank.
Once the plant is created, set the data for that plant. Once it's approved, give me a link to the plant and I will mark it as an encyclopedic page and the effect of that will cause all children plants to receive the data and common name from that plant's entry.
I hope the steps here are clear. Let me know if this is too complicated and I'll try to make this a bit easier.
