What Does A Flowering Magnolia Tree Look Like?

I live in So. NH - have a japanese magnolia that has bloomed beautifully for at least 5 years.  This year it bloomed beautifully but recently I've noticed that the leaves on the tree look brown - like they've frozen or died or are diseased?  Any idea what may have caused this?

The flowers of a magnolia tree are big, and mainly white. Sometimes they are pink. When a magnolia tree blossoms there are no leaves on the tree at the time.