Felt Leaved Yerba Santa

Eriodictyon crassifolia

Small light purple flowers on green branch
Holmwood Canyon | March 2010

Felt leaved yerba santa (Eriodictyon crassifolium) is an open shrub with large, wooly leaves and attractive clusters of lilac flowers. It can reproduce underground stems, producing dense patches.

This is one of several species of Eriodictyon often simply called “yerba santa”. The common name comes from the Spanish padres and means holy herb. As this suggests, these species of yerba santa have impressive medicinal uses. Native Americans made a tea or syrup of the leaves for treatment of respiratory illnesses, coughs and fevers, or they made a poultice for external ailments. Similar uses are advised today by modern herbalists.

Other Common Names:

thick-leaved yerba santa, yerba santa

Description 2,11,23,26,59,174

Felt-leaved yerba santa is an erect, evergreen, clone-forming shrub less than 12 feet (4 m) high, somewhat woody at the base. It often has a pleasant scent.23,59 Gray-green leaves are oval, up to six inches (16 cm) in length, margins somewhat scalloped or toothed. Underground stems (rhizomes) up to 10 feet (3 m) or more in length produce additional upright stems apart from the parent plant, gradually building up a thicket of genetically identical plants. All parts of the plant are densely hairy with white, woolly hairs, giving the plant a grayish appearance.

Lavender flowers are produced from uncoiling flower stalks in clusters at ends of branches. Flowers are bisexual and radially symmetrical, about 1/2 inch (1 – 1.3 cm) across. The calyx is deeply cut into five narrow segments that may be tinged with dark red. The corolla is bell-shaped, the tube opening into five broad lobes. There are five stamens of different lengths that do not emerge beyond the flower throat; anthers are globular and purple with whitish pollen. The pistil has a superior, two-chambered ovary with two slim lavender styles, each topped with a tiny white stigma. Felt-leaved yerba santa blooms mainly between March and June, earlier with early rains.468

The fruit is a dry capsule that splits open in the summer, releasing a few tiny seeds.

Bunches of purple trumpet flowers

Holmwood Canyon | March 2010

Long oval green leaves with serrated edges

Oval leaves with toothed margins | Holmwood Canyon | December 2019

Branches with green leaves and purple flowers

Stand of Yerba santa | Holmwood Canyon | March 2019

Distribution 7,89

Felt leaved yerba santa is native to southern California west of the mountains and south of Point Conception, most often below 4000 feet (1300 m). It can be common in chaparral vegetation and washes and is also found in coastal sage scrub and juniper piñon woodlands. It may be abundant after a fire.

In the Reserve, it is found along the higher trails, especially Holmwood Canyon and Solana Hills. The locations are both near trailheads, which suggests that these were planted, but we have no confirmation.

Reserve map of chaparral, coastal sage scrub and grassland

Classification 2,59

Felt Leaved Yerba Santa is a dicot angiosperm in the borage family (Boraginaceae). Plants in this family often have flowers produced along a coiled stalk (a “scorpioid cyme”). As the stalk unfurls, new flowers open while seed pods 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.41 Other plants in the borage family that are found in the Reserve include  common phacelia (Phacelia distans), coast fiddleneck (Amsinkia intermedia) and fiesta flower (Pholistoma auritum).48

Species of Eriodictyon were previously placed in the waterleaf family (Hydrophyllaceae), based on morphological characteristics. Subsequently, 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 we use for Plant Guide. In 2016, the Boraginales Working Group re-evaluated the borage complex and recommended reclassification into several families.422 Under this scheme, Eriodictyonwould be placed in a small family, the Namaceae. Many botanists have accepted this revision and Eriodictyon is found listed in the Namaceae in the most recent literature.468

The genus Eriodictyon is a small genus with eleven species.  Two varieties of felt-leaved yerba santa are recognized,2,26distinguished mainly by the abundance and characteristics of the hairs on the upper leaf surface. Ours is E. crassifolium var crassifolium.

Jepson eFlora Taxon Page
Purple trumpet flowers

Flowers along an unfurling stalk | Holmwood Canyon | March 2019

Closeup of purple calyx of flower

Magnified calyx, all parts of plant covered with stiff hairs | Holmwood Canyon | March 2019

Closeup of bright purple flowers

Flower with purple anthers, white pollen and paired styles | Holmwood Canyon | March 2019

Ecology  

Felt leaved yerba santa is visited by a large variety of bees and butterflies43,59 that aid pollen exchange between widely separated patches from different clones. Seeds, however, are primarily dispersed by gravity. The seed capsules hang near the ends of branches, several feet above the ground, on flexible brancelets. When disturbed by a bird or a breeze, the springy branchlets shake the tiny seeds out of the capsules.43 Thus, stands of yerba santa are often composed of genetically identical and genetically mixed plants.

Light purple flowers surrounded by soft green leaves

Solana Hills road | March 2019

Purple trumpet flowers with five petals

Solana Hills road | January 2011

Bush with light green leaves

Holmwood Canyon | January 2019

Human Uses  

The Indian tribes of south coastal California, including the Kumeyaay of San Diego and northern Baha, California37,272  and the Chumash of the Santa Barbara area,15,360  used several species of yerba santa extensively for respiratory ailments and general aches and pains. Leaves were boiled into a tea or syrup for colds, coughs, and fever; sometimes the steam was inhaled. The warm tea or a poultice of cooked leaves was sometimes applied to sore joints or other ailments.

Early Padres named the plant “holy herb” for the amazing curative powers, giving this name to several species of Eriodictyon that were used interchangeably – including E. californicum and E. trichocalyx, as well as our species, E. crassifolium. The Spanish adopted these medicinal practices, sometimes improvising by making their yerba santa tea with whiskey.15

Today, similar medicinal uses are still recommended, both by Indians and by herbalists and a variety of preparations from smudge sticks to dried leaves to syrup preparations are available commercially.

Very recently481 researchers at Salk Institute have isolated a compound from felt leaved yerba santa that shows promise for the treatment of Alzheimer’s.

Purple trumpet flowers

Solana Hills road | January 2019

Closeup of green leaf cluster

Holmwood Canyon | March 2019

Tall branches with light green leaves

Solana Hills road | January 2019

Interesting Facts 24

The six-syllable genus name Eriodictyon comes from Greek words meaning “hairy net”, referring to the dense, woolly covering on the leaves of some species.

Bush of green leaves and purple flowers

Holmwood Canyon | March 2010

Small purple flowers

Solana Hills road | January 2019

Underside of leaf coated in short fuzzy hairs

Lower leaf surface covered with a "hairy net" | Holmwood Canyon | March 2018

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