I was about to make a topic about the exact same problem this morning when I saw yours, so I join your topic (hope you don’t mind, I don’t intend to hijack your topic or something but any solution offered will probably work for the both of us). I too tried making plants (in my case, simple moss) by using an object as a particle hair emitter (with objects as hair) and then using a second particle hair system in order to distribute the complete plants on the floor. And in my case too, the leaves disappeared from the moss.
I thought, hey, I like particles! A lot! So why not abuse the randomness hair systems offer to make no 2 moss thingies look the same, right? To necro an old meme:

I hope someone has a solution for this, I mean, there’s GOTTA be a way to have particles emit other particles, right? I mean, people must need this all the time… explosion debris emitting smoke trails, fireworks, vegetation etc. Are we overlooking something really big?