having three each of the sepals and petals
having the parts in threes
• (a.) Having the parts in threes.
<botany> Of a flower, having three segments in each perianth whorl and usually in each whorl of stamens as well. ... (09 Oct 1997) ... 
In threes.
having three each of the sepals and petals
trimerous 1. Having three similar segments or parts. 2. In botany, having flower parts, such as petals, sepals, and stamens, in sets of three.