Fiesta Flower

Pholistoma auritum

bright purple Fiesta Flowers five round petals
Photo credit: Professor David Checkley | Rios trailhead | March 2015

Fiesta flower (Pholistoma auritum) is a sprawling, branching annual vine that blooms in the spring. The long weak stems grow up through surrounding plants, covering the less exuberant shrubs with tangles of cheerful purple flowers.

The stems and leaves of fiesta flower are covered with hairs that are bent backward, allowing the plant to cling and climb. It is said that Spanish señoritas decorated their party skirts and blouses with sprigs of fiesta flowers, which stuck tightly to the fabric. This gives rise to the flower’s common name.

Other Common Names:

Blue Fiesta Flower

Description 3,4,11,23,59

Fiesta flower is a trailing, weak-stemmed annual that uses woody shrubs for support. Stems are square and up to about 5 feet (1.5 m) in length. Stems and leaves are provided with small, stiff, downward-directed prickles that give the plant a grabby, sticky feeling.

Leaves are pinnately divided into 5-9 lobes; lobe margins are smooth. Individual lobes often point toward the base of the leaf. The leaf petioles have broad leafy flaps that wrap around the plant stem.

The showy flowers occur in loose clusters, opening one-at-a-time at the top of a coiled stem that gradually unfurls. Flowers are bisexual and radially symmetrical, broadly cup-shaped, usually less than 1 inch (25 mm) wide. Petals are purple to lavender (rarely blue), paler near the base. In the throat of the flower, five small purple scales surround the base of the stamens, closing the throat and giving the flower a dark eye. Stamens have violet filaments and dark purple anthers which protrude from the flower cup and split longitudinally to release pollen. Sepals have small, leafy appendages that curl outward in the gaps between the unfused sepal tips. Peak bloom is March to May.1

There are one to four seeds in two-chambered, subspheroid capsules. Sepals enclose the developing capsule. With the curling appendages, the structure looks a bit like a green lantern.

Bush with small purple flowers

Santa Carina trailhead | April 2010

Purple flowers on stems with small stiff hairs

Downward-directed spines facilitate climbing | Rios trailhead | March 2014

Unopened flower with short spines

Developing fruit | Rios trailhead | March 2014

Distribution 7,11,59

Fiesta flower is a California native that is restricted to the western United States. In California, it occurs primarily south of San Francisco and below 6000 feet (1800 m). It is found in chaparral, sage scrub, and oak woodlands, especially in damper areas, such as canyons and north-facing slopes.

Fiesta flower occurs sporadically in the Reserve; the best display is found along the south side of Central Basin, between the Rios trailhead and the Gemma Parks loop trail.

Classification 2,59

Fiesta flower is a dicot angiosperm in the borage family (Boraginaceae).2 Plants in this family often have flowers produced along a coiled stalk (a “scorpioid cyme”). As the stalk unfurls, new flowers open just below the coil while seedpods develop along the older stalk. Plants often have small, stiff hairs. Perhaps the best-known members of the Boraginaceae are borage, which is an annual herb native to Central and Eastern Europe and used in soups and salads, and the garden forget-me-not.41Other plants in the borage family that are found in the Reserve include Common Phacelia (Phacelia distans), Coast Fiddleneck (Amsinkia intermedia) and Popcorn flower (Cryptantha intermedia).48

Plants in the borage family are coated by small, stiff hairs, and have flowers that are often located along a coiled stalk. Species of Pholistoma were previously placed in the waterleaf family (Hydrophyllaceae), based on similar morphological characteristics. Subsequently, the availability of molecular data led to several reinterpretations of these plants including the merging of the waterleaf family into the borage family. This is the system currently used by Jepson,2 the authority for this Plant Guide. In 2016, the Boraginales Working Group re-evaluated the borage complex and recommended a separate waterleaf family.422 Many botanists have accepted this revision and Pholistoma is found listed in the Hydrophyllaceae in both the oldest and most recent literature. Research into the relationships between the two families is continuing and the systematics may still be evolving.

The genus Pholistoma is a small genus with just three species. All three occur in the Reserve; the other two (San Diego fiesta flower, P. racemosum and white fiesta flower, P. membranaceum) have small white flowers. Two varieties of blue fiesta flower are recognized. Ours is P. auritum var. auritum. A second variety (var. arizonicum) is not found in the Reserve and is classified by the California Native Plant Society as rare in California but possibly common elsewhere (2B.3).45

Jepson eFlora Taxon Page
spikey green leaf stalk of the Fiesta Flower

Rios trailhead | March 2011

spikey green back of the Fiesta Flower

Rios trailhead | March 2014

a pair of blooming Fiesta Flowers

Rios trailhead | April 2008

Ecology

The small, stiff, downward-directed prickles that cover stems and leaves help fiesta flower cling to and scramble through the surrounding vegetation.59

Fiesta flower is reported to be more abundant after a fire.23

bee enjoying the nectar of a single purple Fiesta Flower

Rios trailhead | March 2014

close up of single purple Fiesta Flower in sun

Rios trailhead | March 2011

free growing purple Fiesta Floweres

Rios trailhead | April 2010

Human Uses

Sources attribute the common name to the story that young Spanish señoritas decorated their party gowns with sprays of fiesta flowers, which, because of their peculiar spiny hairs, adhere tightly to fabric.23,35,174

side shot of purple Fiesta flower

Rios trailhead | March 2014

two small purple fiesta flowers with five round petals

Santa Carina trailhead | April 2010

cluster of purple Fiesta Flowers growing up tree

Santa Carina trailhead | April 2010

Interesting Facts

The scientific name, Pholistoma auritum, loosely translates as “scaly mouth with ears”.21 Pholis is Greek for scale and stoma for mouth. Together they refer to the dark purple scales that close the throat of the flower; auritum is Latin for eared, a reference to the wing-like ears at the base of the leaf.

cluster of free growing Fiesta flowers surrounded by lush greenery

Rios trailhead | April 2010

close up of single purple Fiesta Flower with dark purple center

Photo credit: Denise Stillinger | April 2008

the spikey leaves of the Fiesta Flower resemble arugula

Ear-like hyphenated at the base of the leaf | Rios trailhead | March 2014

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