Complex sentence: About 70% of angiosperm species have endosperm cells that are polyploids, typically triploid (containing three sets of chromosomes) but can vary widely from diploid (2n) to 15n.
Split into simpler sentences: About 70% of angiosperm species have endosperm cells that are polyploid. These are typically triploid (containing three sets of chromosomes) but can vary widely from diploid (2n) to 15n.