Fall means yellow flowers — goldenrods by the dozen, sunflowers, sneezeweed, and many, many more — but not all fall wildflowers are yellow.

There are several deep blue flowers with interesting shapes and habitats. First and foremost, think gentians. They’re found all over the world, except in Antarctica. Here, in Virginia, there are 10 species.

Gentians grow in a wide range of habitats. Some prefer boggy wooded areas. Some grow in full sun in dry areas, and some even grow in the desert. Gentians range in size from short herbaceous plants to tall trees that grow in the rainforest.

Many gentians have trumpet-shaped blooms, and the buds of some species don’t open. They remain closed, and insects must force their way inside. Bumblebees have been observed chewing through to the inside.

With one exception, all of the gentians found in Virginia are pale to deep purplish blue. Most have solid colored blooms, but several have contrasting stripes. In other geographic areas, there are gentians with red and white flowers. Gentians are never shy, retiring plants.

For hundreds of years, humans have used gentians to treat many ailments, flavor liqueurs, help make perfumes. According to Dioscórides and Pliny, Gentius, the last king of Illyria was the first person to discover the many uses of gentians and so the genus was named in his honor.

Research on the phylogeny of gentians has shown that they evolved in the tropics and then spread to northern temperate regions. Some of the oldest gentians are found in tropical Latin America, but most species are now found in the temperate regions of North America, Europe, and Asia.

Fall in our area is the perfect time to look for gentians. The striped gentian (Gentiana villosa) is found at both Holliday Lake State Park and the High Bridge Trail State Park. It’s the only gentian found in Virginia that isn’t bluish purple. The blooms are usually cream to purplish green colored and have green or lilac colored stripes, hence the common name striped gentian. It grows in dry to mesic forests and clearings.

The soapwort gentian (Gentiana Saponaria) is aIso found in our area. It has pale blue to purplish flowers that develop in the axils of the leaves and are funnel-shaped. Like the flowers of other gentians, these are closed or nearly so. Each flower has five lobes that are connected by lighter colored membranes. The soapwort gentian is pollinated by bumblebees. It grows in boggy areas with acidic, nutrient poor soil. There are some in a very wet, boggy area at Holliday Lake State Park.

DR. CYNTHIA WOOD is a master gardener who writes two columns for The Herald. Her email address is cynthia.crewe23930@gmail.com.