Naked-stem Sunflower Helianthus occidentalis

Naked-stem Sunflower is a native herbaceous perennial wildflower found along rocky or sandy riparian areas.  Easy to identify in the wild by the rosette of stalked, basal leaves, 1 1/2 inches across around the base of the plant's 2 to 4 foot stalk and one to four pairs of small, widely spaced, stalkless leaves on the stem. The blades of basal leaves usually have rounded bottom and blunt tips. Their upper blade surfaces are medium green and rough-textured, while their lower surfaces are light green. In addition to their central veins, the basal leaves have 1 to 2 pairs of lateral veins that originate from the bases of their blades. The slender petioles of the basal leaves are 1 to 4 inches long and light green. The flowering stalk is light green to greenish red and glabrous to hairy, mostly naked, except for 1 to 2 pairs of opposite leaves below and a few alternate leaves above. The blades of opposite or alternate leaves are 1 to 3 inches long and 1/4 to 3/4 of an inch across, lanceolate or elliptic in shape and usually smooth (entire) along their margins. The blades surfaces of these leaves are similar to those of the basal leaves, while their petioles are either absent or up to a 1/2 inch long.

The flowering stalk terminates in 1 to 12 flower heads. Individual flower heads are 1 1/2 to 2 1/2 inches across, consisting of 8 to 22 ray florets that surround numerous disk florets. The petaloid rays are yellow and oblong to elliptic in shape. The tiny disk florets have tubular corollas that are yellow and 5-lobed. Around the base of each flower head, there are several overlapping floral bracts. The root system is a narrow taproot with shallow rhizomes that sometimes form vegetative colonies. Plants should be divided every 3 or 4 years to control spread and maintain vigor.

The plant prefers full sun, average dry to medium conditions, and well-drained soil. This wildflower will tolerate partial sun and a wide range of soils, from clay to sand; however, clay soil will need to be amended. On deep fertile soil, it is not competitive with other species of plants and is one of the less aggressive Helianthus spp. (sunflowers).

The genus name is from the Greek helios meaning sun and anthos meaning flower. The species name means west in the sense that North America is west of Europe and not that the plant is native to the west.

Insects, Diseases, and Other Plant Problems:

No serious insect or disease problems; however, you may need to stake taller plants for support.

More information on Helianthus.