Pronounciation: Te-tra-ne-UR-is a-ca-UL-is
Sunset 7-13, 18-21
Landscape Use: Border edging, flowering accent, xeriscape, small intimate desert gardens. Most attractive when planted in mass at about 18 inches on center.
Form & Character: Herbaceous perennial, stem less, tufted, free flowering.
Growth Habit: This is a short lived perennial with a compact and basal branching habit to 10 inches tall with a spread of up to 18 inches wide.
Foliage/Texture: Small, linear, glabrous to 2 inches long, some abaxial pubescence; very fine texture.
Flowers & Fruits: Bright yellow ray flowers to 1 inch across on a 12 inches tall scape. Fruits are fuzzy achenes (one seed attached to inside of ovary at one point) about 1/8 inch long. Senescent fruit stalks are unsightly.
Seasonal Color: Yellow flowers throughout the year; however, most prolific during winter and spring.
Temperature: Hardy to 0oF, but struggles in mid-summer when daytime temperatures are consistently above 105oF.
Light: Full sun
Soil: Well-drained soils are needed.
Watering: Apply water on a regular intervals, but allow to dry in between water applications.
Disease and pests: Basal fungal root rot in poorly drained soil is common.
Additional comments: Commercially introduced as a landscape perennial to the Phoenix area in the 1990's. Generic name compounded from Greek word humen "membrane" and oxys "sour", likely derived from translucent scales at base of flower and bitter taste of several species in the genus. Acaulis means without a stem. This plant was first described by Frederick Pursh (1774-1815). Has a relatively significant taproot and will not transplant. In the end it seems to only last about 3 to 4 years in Phoenix landscapes because of heat sensitivities.