Saturday, October 10, 2015

Native Spotlight: Gentiana andrewsii

Guest Blog by Rachel Shaw

Gentiana andrewsii, commonly called Closed Gentian or Bottle Gentian, is a gorgeous, late-blooming garden treat. The petals of the beautiful blue flowers remain tightly closed, looking like large buds on the verge of bursting into full bloom.

This is a plant that likes relatively moist rich soil. This summer’s extremely dry weather was harder on my Closed Gentians than on most of my native plants, even with some supplemental watering. I worried that they wouldn’t flower this year. The tiny immature flower buds seemed to stay that way for weeks, although perhaps that is usually the case and I just hadn’t noticed. But I needn’t have worried. Even before the recent days of steady rain, the flowers seemed almost overnight to have grown and plumped up. The foliage is red-tinged rather than the deep green of previous years. But the rich blue of the flowers is stunning, and even more so on gray dreary days.

Closed Gentians are pollinated by bumble bees, said to be the only pollinators strong enough to force their way into the tops of the tightly closed flowers to get to the nectar. I was surprised when I first learned this, because most of the bumble bees I’ve seen on these plants have been on the outside facing down, clasping the base of the flower.

Just recently I just came across a link to a book, Bumble Bees of North America: An Identification Guide by Paul H. Williams, et al., with a fascinating observation. The authors note that bumble bee species with long tongues are better than short-tongued species at reaching nectar in long tubular flowers such as Closed Gentians. However, some short-tongued bumble bee species have learned to pierce the base of the Closed Gentian flower to get at the nectar. I have no idea if that’s what I’ve been observing. Maybe the bees are just resting after a difficult fight into the top of the flower! Please let me know if you have any knowledge or observations about this. 

About the author:
Rachel Shaw focuses on vegetable gardening and growing native plants in her small yard in Rockville, MD. She blogs at

This guest blog post is part of a monthly Native Plants series posted around the 10th of each month.


TiiuGardens said...

Hi Rachel -

Thanks for highlighting this particular flower. I've never paid attention to it but the fact that it's a native will make me take a closer look and consider it for my own garden.

As for the bees, I have noticed that they do indeed pierce through the bottom of a blossom rather than enter from the top of the open bloom. I've seen this on my Salvia guaranitica 'Black and Blue' which is too small to let a fat bumblebee in from the top and think I have seen it happening on other blooms also, I just can't recall which at the moment., possibly South African foxglove which has a long tube.

Happy gardening!

Tiiu in Baldwin, MD

Botania said...

With further observation I see that smaller bumble bees force their way into the top of the flower but leave after a few seconds. According to what I was reading, bumble bees that get inside the flower stay for about a minute to gather nectar; I haven't seen this. Maybe the flower-piercing bees are getting all the nectar. It's fascinating.