Psilostrophe cooperi (A. Gray) Greene
Whitestem Paperflower, White-stem Paper-flower, Yellow Paper Daisy
Asteraceae (Aster Family)
Synonym(s): Riddellia cooperi
USDA Symbol: PSCO2
White-stem paper-flower is a small, deciduous sub-shrub with many erect, white-woolly stems rising 8-20 in. from the base. Flowers are showy and yellow, terminating the upper branches. Many well-branched leafy stems, woolly at the base, form a nearly round plant covered with loose wool, usually bearing only one yellow flower head at the end of each branch. The ray flowers turn papery and persist long after they have lost their yellow color.
White-stem Paperflower forms brilliant yellow globes. Its rays become dry and papery, remaining on the plant long after flowering. There are several closely related species.
From the Image Gallery
Plant CharacteristicsDuration: Perennial
Habit: Subshrub , Shrub
Leaf Retention: Deciduous
Size Notes: Up to about 20 inches tall.
Fruit: Fruit is a cypsela (pl. cypselae). Though technically incorrect, the fruit is often referred to as an achene.
Bloom InformationBloom Color: Yellow
Bloom Time: Feb , Mar , Apr , May , Jun , Jul , Aug , Sep , Oct , Nov , Dec
DistributionUSA: AZ , CA , NM , NV , UT
Native Distribution: Extreme s.w. UT & w. NM to s. CA & n.w. Mex.
Native Habitat: Deserts & mesas; 2000-5000 ft.
Growing ConditionsLight Requirement: Sun
Soil Moisture: Dry
Soil Description: Rocky soils.
Conditions Comments: The main bloom period is in spring, but if summer rains have been good, the plants will flower again in fall.
Web ReferenceWebref 38 - Flora of North America (2019) Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
Webref 23 - Southwest Environmental Information Network (2009) SEINet - Arizona Chapter
Additional resourcesUSDA: Find Psilostrophe cooperi in USDA Plants
FNA: Find Psilostrophe cooperi in the Flora of North America (if available)
Google: Search Google for Psilostrophe cooperi
MetadataRecord Modified: 2023-01-13
Research By: TWC Staff