• Double O Arch


    National Park Utah

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Hoary Spine Aster

Machaeranthera canescens

Machaeranthera canescens

Family: Asteraceae (A Utah Flora – Compositae) – Sunflower Family

Biennial (winter annual) or short-lived perennial herbs from taproots; stems 3.2” to 2' (8 to 60 cm) tall or more

Leaves: alternate; simple; entire or pinnatifid to toothed or lobed; 0.4” to 4” (1 to 10 cm) long, 0.04” to 0.88” (1 to 22 mm) wide

Flowers: 15 to 25 pink to pink-purple or white rays, 0.2” to 0.48” (5 to 12 mm) long, 0.06” to 0.1” (1.5 to 2.5 mm) wide ; involucres 0.24” 0.48” (6 to 12 mm) high, 0.24” to 0.72” (6 to 18 mm) wide; flower head appears to be a single flower, but is composed of several flowers (a composite)

Pollinators: other genera in this family are pollinated by insects

Fruits: achene – 1 seeded with hard shell

Blooms in Arches National Park: late April, May, June, July, August, September, October, November

Habitat in Arches National Park: desert shrub and pinyon-juniper communities

Location seen: upper Courthouse wash, Windows road, outside Arches National Park in Bull Canyon (near Gemini Bridges)

Other: The genus name, “Machaeranthera”, means “sickle anther” and refers to the shape of the anthers. The species name, “canescens” means “gray hairs or grayish”.

This plant is an endemic.

This family is the most advanced and complex of the dicots. The family is rich in oils and resins and is found in every part of the world, but is infrequent in the tropical rainforest. Aquatic or semi-aquatic species are also uncommon.

Did You Know?

Ed Abbey

Edward Abbey worked as a seasonal park ranger at Arches in the late 1950s. His 1968 memoir of this experience, "Desert Solitaire," has become a classic of desert literature.