Black Sage

Black sage (Salvia mellifera) is a dominant shrub of the coastal sage scrub, where it is a major contributor to the characteristic pungent aroma. It has small dark green, resinous leaves and numerous pale lavender flowers, which occur in whirls around the upright stalks.

Like many plants of the coastal sage scrub, black sage is seasonally dimorphic. During the rainy period, leaves are relatively large. These are replaced during the dry summer months with smaller leaves that tend to be curled to reduce transpiration. These summer leaves can respond quickly to a summer shower, but the lush green leaves of winter and spring do not reappear until winter rains begin.

Description ^2,4,11,59

Black sage is an aromatic perennial subshrub, generally less than 5 feet (1.5 m) high. Leaves are yellow green to green, oval, to 3 inches (7.5 cm) long and 3/4 inches (1.8 cm) broad; margins have small, rounded teeth. Leaves are opposite on the stems; leaf surfaces are conspicuously rugose. Stems are square in cross section. Plants are drought-deciduous or semi-deciduous but may be evergreen in more moist habitats.⁴

Flowers range from white to blue- lavender; in the Reserve, they are usually pale lavender. They are arranged in dense whirls along a stem that often rises above the vegetation. Flowers are  bilaterally symmetrical. Five petals are fused at the base into a tube; the outer portions are fused into lips. Two petals form the upper lip, which has two rounded lobes and flares outward and upward. The middle petal of the lower lip is large with two lobes; the two lateral petals of the lower lip appear as smaller “ears”. The style extends from the throat and is split into two unequal branches; the lower, longer branch is curved downward. There are four stamens fused to upper portion of the flower throat; two of these are short and sterile; the anthers of the other two extend outward. Major bloom time is April – July.¹

Each flower produces a fruit with 1-4 seeds. Whirls of dried fruits remain on the stem for some months after the seeds are gone.

Classification ^44,59

Black sage is a dicot angiosperm in the mint family (Lamiaceae). Members of this family often contain essential oils that give a strong scent, which may vary from pleasantly minty, to pungent and less pleasant. Typically, stems are square and leaves arranged in opposite pairs along the stem. Flowers are strongly bilateral, with both sepals and petals fused into two lips.  Flowers are often arranged in whirls. Many of our important culinary herbs belong to this family, including oregano, thyme, rosemary, basil, mint and lavender. There are no poisonous plants in the mint family.³⁴

The Salvia is the largest genus in the family and contains the true sages. Species in the genus are distinguished by details of flower structure, especially the staminal lever mechanism that causes the stamens to pivot downward and deposit pollen on the backs of pollinators. Species often have flowers arranged in distinct whirls. Two other sages are found in the Reserve: white sage (Salvia apiana) and Cleveland sage (Salvia clevlandii).

Several varieties of S. mellifera have been described. Currently, none are considered valid.

Ecology

Like many plants of the drought-adapted coastal sage scrub, black sage is seasonally dimorphic, producing larger leaves during the wet periods and replacing them with smaller leaves during the dry months. The area of a summer leaf is about 20% that of a winter leaf.⁶ The root system is branched and fibrous; most roots are within 5 inches (13 cm) of the soil surface, but they may extend laterally twice the height of the parent plant.³⁸ This root structure allows black sage to take advantage of early winter rains.⁵

Although the abundant nectar attracts a large variety of pollinators, from small solitary bees and flies to butterflies and hummingbirds, the relatively narrow-necked, long tube of the black sage flower deters the larger pollinators.⁷² The pollen of black sage begins to mature before the female style is receptive, reducing the chance of self-fertilization.⁷² Each fertile anther is fused at the base to a sterile one, forming an L shape. As an insect enters the corolla tube, it brushes against a shorter stamen which acts as a trigger, bending the fertile stamen down to touch the insect’s back, thereby depositing pollen for transport to another flower.¹¹The pollen of black sage begins to mature before the female style is receptive, reducing the chance of self-fertilization.⁷²

Populations of black sage are decreasing due to loss of habitat, and competition from non-native grasses which are favored by increasing fire frequency and increasing nitrogen input.¹¹ The plant is also sensitive to air pollution from sulphur dioxide and possibly ozone⁵ and has been recommended for use as a pollution monitor.⁵

Human Uses

The Kumeyaay bathed with a tea of stems and leaves as a treatment for flu, rheumatism and arthritis,¹⁶ and Luiseño harvested the tiny high-protein seeds for food.¹⁷ Numerous other medicinal uses have been described, including treatment for ulcers and stomach inflammations, sore throats, and mucous secretions of the sinuses, throat, and lungs.³⁴

Leaves can be used as a seasoning; flavors tend to be stronger than those of the culinary sage (Salvia officianalis) and there is considerable variability among plants. Honey from black sage is considered one of the best.^5,34

Black sage is used in native plant gardens,⁷⁹ although not as often as its more spectacular relatives such as white sage (S. apiana) and Cleveland sage (S. clevelandii). Several low-growing cultivars make good ground covers.²⁴ Black sage is recommended for erosion control in coastal sage scrub habitats.⁵

Interesting Facts

The origin of the common name, black sage, is disputed. Most sources give one or more of three explanations: the dark leaves look black from a distance, especially during dry conditions; the stems dry dark and look black; the whirls of dried seedpods look black.^23,59 None are completely satisfying. An interesting alternative is offered by a gardener who found her hands dyed black after a few hours of pruning black sage.⁷³

The Latin species name, mellifera, means “honey bearing”,²¹ referring either to the prodigious amount of nectar produced under favorable conditions or the high quality of black sage honey – or both.