Common Name: sulphur flower
Type: Herbaceous perennial
Family: Polygonaceae
Native Range: Southwestern North America
Zone: 4 to 8
Height: 0.50 to 1.00 feet
Spread: 1.00 to 3.00 feet
Bloom Time: May to July
Bloom Description: Yellow to cream
Sun: Full sun
Water: Dry to medium
Maintenance: Low
Suggested Use: Ground Cover
Flower: Showy, Fragrant
Attracts: Birds, Butterflies
Culture
Grow in lean, gritty, lime-free, dry to medium, well-drained soils in full sun. Sharp soil drainage is important. Wet soils in winter can be fatal. Plants have good tolerance for drought, poor soils, rocky soils and high heat. Plants may be grown from seed and may self-seed in the garden. Notwithstanding its natural habitat in western alpine areas, this species adapts to eastern U.S. gardens at lower altitudes better than most of the eriogonums. Basal foliage is evergreen to semi-evergreen.
Noteworthy Characteristics
Eriogonum umbellatum, commonly called sulphur flower, is a highly variable wildflower that is native to dry rocky soils in rocky forests, foothills, mountain slopes and mountain ridges from British Columbia and Alberta south to southern California, Arizona and the eastern edge of the Rocky Mountains in Colorado. Flora of North America lists 41 different varieties of this plant. This is a spreading, mat-forming perennial that is noted for its tiny sulphur yellow flowers which bloom from late spring into summer in compound umbels (rounded flower clusters to 4" wide) located atop leafless flowering stalks rising to 12" tall. Each umbel is subtended by a whorl of leaf-like bracts. Flowering stalks rise well above low-growing basal mounds of leathery, spatula-shaped, gray-green leaves (each 1/2" to 1.5" long). Leaves appear both in a basal rosette below the primary flowering stalk and as whorls at the ends of short woody stems emanating from the woody plant base. Leaves acquire red tones in fall. Each bell-shaped flower (to 1/4" long) has 6 petal-like lobes. Flowers emerge sulphur yellow to cream, but age to an orange-yellow. Flowers ultimately age to brown and are attractive in dried arrangements. Plants will spread over time to 1-3' wide. Flowers are attractive to a large number of butterflies and bees. Birds are attracted to any seed that develops. This plant is also commonly called sulphur buckwheat.
Genus name comes from the Greek words erion meaning wool and gony meaning a knee for the "wooly" nodes.
Specific epithet is in reference to the almost umbrella-like arrangement of the flowers.
Problems
No serious insect or disease problems. Rust and powdery mildew may occur.
Uses
Excellent selection for dry areas of the landscape. Effective in rock gardens and butterfly gardens. Mounds, banks or slopes. Ground cover.