Felt Leaved Yerba Santa

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.

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.

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.

Ecology  

Felt leaved yerba santa is visited by a large variety of bees and butterflies^43,59 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.

Human Uses  

The Indian tribes of south coastal California, including the Kumeyaay of San Diego and northern Baha, California^37,272  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.

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.