Casting question

I’ve recently begun my hand at casting with scrap brass from my job! I just built a propane burner but cracked my crucible after two pours. While I wait for a new one, I had a question popped by a friend. Normally I use candle wax or crayons to make the investment in the plaster molds, he suggested using a sunflower from his garden in said plaster molds. Now I’m skeptical but would the plant leave any negative material or just burn all the way out at those high temps? He’s looking for an anniversary gift and it seemed worth the question? Sorry if this is idiotic or a waste of time but I’m brand new to this. Any suggestions/tips would be great, thank y’all for any info you can spare!