They are called "naked ladies" because their leaves die before the flower stalks emerge, an adaptation to environments with a wet spring but dry summer. Those stalks look like weird little aliens sprouting from the soil: tall green rods with fat pink buds on the ends. I strongly suspect them of having inspired some science fiction paintings I've seen.
This is probably my favorite type of lily. I love how they show all the pastel colors in a blur of peach, pink, lavender, pale blue, butter yellow, and green.