Help needed for green-fingered friend.

Hello.
It's my friend's birthday soon, and she's asked me to get something that I can't find. I was hoping someone could help.
She said she wanted a 'root developer' (after googling it, I'm not very confident that's actually what it's called.) She described it as a model tree made from metal that has test tubes on the end of the branches. In these test tubes you can grow seeds. I can't find one anywhere, and her description was quite vague. Does anyone know what she means? All help would be really appreciated.
Thanks,
claire