Common Name: California Laurel

General Information

Umbellularia californica is a much-branched evergreen shrub or a tree with a dense, rounded to pyramidal crown; it usually grows from 3 - 25 metres tall. The smallest forms are found under dry conditions, the plants reaching their greatest size on deep alluvial soils near rivers[, , ].
A multipurpose plant it was commonly used by native N. Americans to provide food, medicines and a range of products. The wood is highly valued and is often harvested for commercial use; the plant is used in modern herbalism; it is a popular wild-harvested food; whilst the leaves are sold commercially as a food flavouring. The plant is often grown as an ornamental, where it can be used as a hedge.

Known Hazards

The foliage can cause skin irritations[, ]. A volatile oil in the leaves can cause sneezing and headaches if inhaled[].

Botanical References

,

Range

South-western N. America - California to Oregon

Habitat

Canyons and valleys, lower mountain slopes, flatlands, alluvial flood plains, hillsides etc, on various soils and often in shade; at elevations up to 1,500 metres[, , , ]. The best specimens are found in deep rich soils of valley bottoms[].

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Evergreen Tree
Height	25.00 m
Growth Rate	Medium
Cultivation Status	Ornamental, Wild

Cultivation Details

Umbellularia californica grows in the cool, humid maritime climate of dense coastal forests in Oregon and in the mediterranean climate of Californian hardwood forests and chaparral[]. Older plants are hardy to about -15°c when growing in a position that is sheltered from cold drying winds, and have been known to tolerate short-lived extremes down to -25°c in their native environment, but young plants require some frost protection[, ]. Even mature plants can be damaged in severe winters[]. Mean annual rainfall can range from 338 - 2,118mm in its native range[].
The plant tolerates a wide range of conditions and does well in full sun to deep shade, though it grows fastest and tallest in deep, fertile soils that are well drained, with regular water availability[]. It requires a well-drained moisture retentive lime-free soil in a sunny position[]. Prefers an abundant supply of moisture in the growing season[]. In the wild the plants are found on loam, sandy-loam, or clay soils, with a pH ranging from 5.7 to 7.4[].
The leaves are harvested commercially in California and sold as a bay-leaf substitute[].
The leaves emit a powerful camphor-like scent when bruised[]. So strong is the aroma that it can cause headaches and dizziness[].
Plants can take 30 - 40 years from seed before they begin to produce seed, they then usually fruit abundantly[].
A very large and beautiful tree fruited regularly at Kew Gardens in London, England, producing viable seed, until it was blown down in the severe storms of October 1987[].
The plant can regenerate after fires of light to moderate intensity. The trees can sprout from the root crown and seed germination may increase following fires[].
A serious management problem of this species is heart rot. The fungus Ganoderma applanatum, which causes this
disease, canl infect even young trees. Heart rot can be virtually eliminated from a stand by cutting down trees to stumps of less than 20cm in height in order to promote root crown sprouting. These root crown sprouts have a very low incidence of heart rot[].
The tree is allelopathic - the leaves contain water-soluble terpenes which are leached out by rain and enter the soil where they retard the root elongation of neighbouring plants. This has been shown to severely reduce the growth of conifer seedlings, for example[].

Edible Uses

Seed - cooked[]. It can be roasted and eaten or can be ground into a powder that is used with cereal flours in making bread[, , , ]. The seeds were roasted until they were crisp and brown - this roasting removes much of the pungency, with just a hint of acridity remaining, and gives the roasted nuts a spicy or coffee-like flavour. The parched nuts can then be shelled and either eaten whole or pounded into a meal[]. The roasted seeds were eaten as an accompaniment with clover in order to prevent bloating[]. The oily meal is easily pressed into small cakes that are then sun-dried and stored for use in the winter[].
The seed meal was also made into a beverage that was said to taste like chocolate[].
A bitter quality in the seed is dispensed by roasting or parching the seed[, ].

Fruit - raw or cooked[]. The fruits were sun dried until the fleshy outer part had split and loosened from the pit. The dried flesh was removed from the seeds ready to eat. Only the thicker portion (the bottom third of the outer dried fruit) was eaten as the upper, thinner part contains a higher concentration of the acrid oil that is a component of all parts of the tree[]. The deep brown-purple fruits are around 10 - 25mm in diameter, containing a single, large seed[].

The leaves are used as a condiment in cooked foods. They are a bayleaf substitute but with a much stronger flavour[, , ]. Used for flavouring soups, stews etc[].

A tea is obtained from the leaves[].

A coffee substitute is obtained from the root bark[, ].

Medicinal

California laurel was employed medicinally by some native North American Indian tribes who used it particularly as an analgesic to treat a variety of complaints[]. It is still occasionally used in modern herbalism, being valued for its beneficial effect upon the digestive system.

The leaves are analgesic, antirheumatic, nervine and stomachic[, , , , ]. Although the aroma of the leaves is known to cause headaches, they have also been used as an infusion and a poultice to treat this affliction[, , , , ]. The leaves are also used internally to treat neuralgia; intestinal cramps and gastro-enteritis; colds; sore throats; and to clear up mucus in the lungs[, ]. An infusion has been used by women to ease the pains of afterbirth[].
Externally, an infusion has been used as a bath in the treatment of rheumatism and neuralgia[, ]. A decoction of the leaves has been used as a wash on sores and to remove vermin from the head[]. The leaves have been tucked into and under hats or into headbands made of laurel twigs in order to relieve headaches[]. A hot poultice of laurel leaves mixed with nutmeg, cinnamon, and olive oil, has been applied repeatedly to the head of persons suffering fits until they regained consciousness[].
They are harvested as required and can be used fresh or dried[].

The seeds have been eaten as a stimulant[].
A poultice of the ground seeds has been used to treat sores[].

Agroforestry Uses:

The plant can be trimmed and is sometimes grown as a hedge[].
California laurel is used for a variety of rehabilitative purposes within its native range. It has been utilized in riparian and wildlife habitat reclamation projects in Berkeley, the Santa Clara Valley, and Los Angeles County, California. It has also been used in watershed projects for flood control and stream channel restoration[].

Other Uses

All parts of the plant, but especially the leaves, contain an aromatic camphor-like essential oil that has cooling, irritant, insecticidal and germicidal qualities[]. It is obtained from the leaves by steam distillation[, , , ].

The leaves are used as an insect repellent, they are especially effective against fleas[, , , , ]. They have disinfectant properties and contain small quantities of the essential oil camphor[, ]. The leaves are burnt as a fumigant to get rid of fleas[].

The leaves have been hung in bunches to freshen the air[]. Some caution should be taken here - the aroma of the leaves can give some people headaches[].

Beige and green dyes are obtained from the fruits (used without the seeds). Very aromatic, the dye retains its fragrance for many years[].

The seeds, which can be up to 20mm in diameter, are used traditionally as beads in necklaces[].

Wood - hard, close grained, heavy, strong, takes a high polish. A beautifully textured, high quality wood, it is used for high quality cabinet making, furniture, panelling etc[, , , , ]. Burls, and other growths with unusual grain, are especially prized for making gifts, novelties, and wood carvings, they are marketed as 'myrtlewood'[, ].

Propagation

Seed - it has a limited viability and is best sown as soon as it is ripe in the autumn in a greenhouse[]. Stored seed should be sown as early in the year as possible in the cold frame because a period of cold stratification can improve germination rates[]. In the wild the seed germinates as soon as it falls to the ground in the autumn[]. When they are large enough to handle, prick the seedlings out into deep, individual pots to allow for root development and grow them on in the greenhouse or cold frame for at least their first winter. Plant them out into their permanent positions in late spring or early summer, after the last expected frosts.
Cuttings of half-ripe wood, 7 - 10cm with a heel, mid summer in a shaded frame. Pot up in spring. Good percentage[, ].
Layering.