Prairie gentians (Gentiana) The blossoms of closed (or bottle) gentian (Gentiana andrewsii) never open. In order for the plant to be pollinated, insects must burrow through the petals. Variegated petals range in hue from light blue to blue violet. photo by Valarie Spale Bottle gentian is a short plant growing 1-3 feet in height. Look for these blue surprises in moist praries between August and October. photo by Tim Burke In September when the prairie begins to dry and greens turn tawny, the vibrant blue of bottle gentian startles the senses. Prairie enthusiasts await the coming of September in hopes of discovering prairie (or downy) gentian (Gentiana puberulenta.) In contrast to the drying prairie, the blossoms of downy gentian stand out like lush blue stars. photo by Tim Burke The sapphire color of the downy gentian makes it one of the most beloved prairie blossoms. photo by Tim Burke