What is referred to by 'citron'?

Based on the clue 'citlaltepetl on the border of the states of veracr...', what is the answer? Based on the clue 'citrine a translucent yellow quartz is often sold ...', what is the answer? Based on the clue 'citrine is a yellow variety of this mineral', what is the answer? Based on the clue 'citrine which is cut into gemstones is a variety o...', what is the answer? Based on the clue 'citrus drink franchise owned by the conqueror of g...', what is the answer? Based on the clue 'citrus fruit named for the resemblance of its apex...', what is the answer? Based on the clue 'citrus fruits including limes were introduced to t...', what is the answer? What is referred to by 'citrus limon'?