Complex sentence: Tepals are elements of the perianth, or outer part of a flower, which include the petals or sepals, but the term tepal is applied when all segments of the perianth are of similar shape and color, or undifferentiated.
Split into simpler sentences: Tepals are elements of the perianth, or outer part of a flower, which include the petals or sepals. The term tepal is more often applied specifically when all segments of the perianth are of similar shape and color, or undifferentiated.