Scarlet Gilia

Ipomopsis aggregata (Polemoniaceae)

Photo from RMBL Archives
Scarlet gilia is a perennial wildflower of western North America. Many of its common names, including skyrocket, fairy trumpet, and rocket flower, derive from characteristics of its flowers. The flowers are trumpet-shaped, typically 5-8 cm (2-3 in.) long with red petals that are fused into a long tube at the base and divide into a 5-pointed star shape at the tip. Flower clusters and leaves typically are displayed on a single flowering stalk that ranges from 30-90 cm (1-3 ft) tall, although multiple stalks sometimes are produced. Scarlet gilia is sometimes called skunkweed for the skunky smell produced by oils secreted by glandular hairs on sepals and stems. The oil helps to repel ants that can damage the sex parts inside flowers.

Scarlet gilia prefers well-drained soils in full sun. It commonly occurs in dry meadows and disturbed areas around the Rocky Mountain Biological Lab, and is common from sagebrush flats to montane and alpine meadows throughout the West. This species commonly occurs with big sagebrush, lupine, delphinium, and penstemon.

Life History
Scarlet gilia is a monocarpic perennial, meaning it grows for several years as a cluster of leaves close to the ground, flowers in a single summer, and then dies after flowering. In the high-elevation setting of the RMBL, individuals grow for 1-8 years before they flower, producing anything from a few to hundreds of flowers and seeds. Their flowering season last about six weeks, from late June to early August. Because individuals flower only once, scientists can estimate a plant’s entire lifetime reproductive success in one field season, making scarlet gilia a favorite subject of study by pollination biologists at RMBL.

I. aggregata flowers contain both male and female sex parts. Each flower sheds pollen before the female part (the stigma) matures. Nectar is produced by glands at the base of each flower tube. The red, tubular flowers are mainly pollinated by broad-tailed (Selasphorus platycercus) and rufous (S. rufus) hummingbirds at the RMBL, although in some years butterflies, hawkmoths, bumble bees, and solitary bees can be important pollinators. Hawkmoths are a particularly important pollinator in other parts of scarlet gilia’s range.

Other Interactions
Although pollinators that visit I. aggregata benefit the plant by moving pollen from individual to individual and thus enabling sexual reproduction, other animals are enemies. In addition to ants that may damage sex parts, deer and elk, along with some smaller mammals, browse the flowering stalks. Boring insects may tunnel into the roots or stem and kill a plant. Small flies lay eggs on flower buds, and the larval flies that hatch from the eggs consume the developing seeds. One species of bumble bee “robs” nectar from flowers by biting a hole at the base of the flower tube and licking it out, without moving any pollen. These nectar robbers cause the flowers to be less attractive to “legitimate” pollinators such as hummingbirds.

Encyclopedia of Life
See images and distribution maps of Ipomopsis aggregata at the Encyclopedia of Life.

Learn More
Explore Selected RMBL Pollination Research to learn about some of the RMBL research involving this model organism.