Gentiana andrewsii (bottle gentian)

These tubular flowers bloom for about a month but never actually open. They are pollinated by bumblebees, who are strong enough to open the petals and squeeze their way in as shown here. Typically dark blue, but colors may range from light purple to fuchsia. Slow-growing but long-lived. Does best in consistently moist soil, especially for the first few years while the taproot gets established.