Pistils also die from old age, wind burn, mishandling...and multiple pistils are common.

TsarBomba: Perhaps a little more learnin' before offering advise is a good idea. Sensimilla (sensi) is a term refering to flowers produced from a female plant (in this case, cannabis) that has not been fertilized and doesn't contain seeds.

Seeded calyx's have a yellowish 'racing stripe' from base to tip, and they don't grow-out fresh pistils once seeded. Just like people's noses, earlobes and ego's grow with age...so do the calyx's.