This species is often confused with Mahonia trifoliolata, which differs in only ever having 3 leaflets per leaf[].
The genus Mahonia is not universally accepted. Many botanists prefer to treat it as part of Berberis - as per the Flora of N. America[]. However, although they are very closely related (and there are some intergeneric hybrids), from the point of view of the gardener they are quite distinct genera. We are therefore following the treatment in the Flora of China[] which treats them as distinct. There is, however, at least one major revision (of the Chinese genera) currently (2016) in preparation and we will review the position of Mahonia once we have seen that revision[].

Common Name: Mahonia

General Information

Mahonia fremontii is an evergreen shrub growing from 1 - 4.5 metres tall. The stems have elongate primary shoots and short to somewhat elongate axillary shoots[].
The plant is harvested from the wild for local use as a food, medicine and source of a dye. It is grown as an ornamental in gardens.

Known Hazards

All parts of the plant contain the alkaloid berberine - this is most concentrated in the roots, stems and inner bark, and least concentrated in the fruits. In small quantities berberine has a range of effective medicinal applications but, in excess, can cause vomiting, lowered blood pressure, reduced heart rate, lethargy, and other ill-effects.
The fruit of most, if not all, members of this genus are more or less edible and can be eaten in quantity since the levels of berberine in the fruit are very low.

Botanical References

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Range

South-western N. America - California, Nevada, Utah, Colorado, Arizona, New Mexico

Habitat

Dry rocky places, especially in piñon-juniper woods, often in gravelly soils[, ]. Slopes and flats in desert grassland and pinyon-juniper woodland; at elevations from 1,100 - 2,400 metres, occasionally to 3,400 metres[].

Properties

Edibility Rating
Medicinal Rating
Habit	Evergreen Shrub
Height	2.50 m
Growth Rate	Slow
Pollinators	Bees
Cultivation Status	Wild

Cultivation Details

Mahonia fremontii is native to the hot and semi-arid regions of southwestern N. America and often does not grow so well in more humid climates. It can tolerate temperatures down to about -10°c[].
Unlike most members of this genus, this species requires a dry, perfectly drained position in full sun, a gritty slightly acid soil is best[, ]. It grows best on a sunny south facing wall in Britain[] and does well in a hot, dry position[]. It requires a position sheltered from strong or cold winds[].
Plants are slow-growing[].
Hybridizes freely with other members of this genus[].
The flowers are refreshingly fragrant[].
Some named forms have been developed for their ornamental value[].
Some Berberis/Mahonia species (especially Berberis vulgaris) harbour the black stem-rust fungus (Puccinia graminis Persoon). This is a major disease of wheat and barley crops and can spread from infected barberries to the grain crop. The sale or transport of susceptible or untested species of Berberis is illegal in the United States and Canada[]. This species is susceptible to infection by the fungus[].

Edible Uses

Fruit - raw or cooked[]. It is usually cooked[]. An acid flavour but it is rather nice raw, especially when added to muesli or porridge[]. Unfortunately, there is relatively little flesh and a lot of seeds[]. The ovoid fruit is about 15mm long[].

A beverage has been made from the fruit[].

Medicinal

The plant has been used as an aid for the gums[].

The roots are bitter tonic, hepatic and laxative[]. An infusion has been used to promote digestion[].


This is one of several species closely related to the Oregon Grape (Mahonia aquifolium) and with very similar medicinal uses[]. These uses are:-

Oregon grape was often used by several native North American Indian tribes to treat loss of appetite and debility[]. It is still a popular remedy in modern herbalism, being used mainly in the treatment of gastritis and general digestive weakness, to stimulate liver, kidney and gallbladder function and to reduce catarrhal problems[, , ]. Extensive trials have shown that a cream containing the root or stem extract is a safe and effective treatment for psoriasis and other skin conditions.

The root and root bark are alterative, antibacterial, antioxidant, blood tonic, cholagogue, diuretic, laxative and tonic[, , , ]. It improves the digestion and absorption and is taken internally in the treatment of psoriasis, syphilis, haemorrhages, stomach complaints and impure blood conditions[, , ].
Externally, it is used in the form of a cream to treat skin conditions such as psoriasis, whilst a decoction has been used as a gargle for treating sore throats and as a wash for blurry or bloodshot eyes[].
The roots are harvested in late autumn or early spring and dried for later use[].

The fruit is an excellent gentle and safe laxative[].

In Germany, several studies have indicated that Mahonia aquifolium exerts anti-psoriasis activities though inhibiting antiinflammation and hyperproliferation of keratinocytes, and that alkaloids may be responsible for the anti-psoriasis activity of this plant[].
Mahonia species have a long history of medicinal usage, with several members of the genus being commonly used in traditional medicine and also in modern herbalism. They are employed in the treatment of a wide range of conditions and have, in particular, been demonstrated to exert good efficacy in the clinical treatment of dysentery, internal and external haemorrhage, acne vulgaris and chronic pharyngitis amongst other diseases. Phytochemical research into this genus has resulted in the identification of more than 150 chemical constituents, amongst which alkaloids are predominant. The isolated compounds and crude extracts have been shown to exhibit a wide spectrum of in vitro and in vivo pharmacological effects, including antimicrobial, anti-inflammatory, hepatoprotective, antioxidant, antimutagenic and analgesic properties[]
Berberine, an alkaloid that is universally present in the rhizomes and stems of Mahonia species, has been shown to have a marked antibacterial effect[] and is also used as a bitter tonic[]. Since it is not appreciably absorbed by the body, it can be used orally in the treatment of various enteric infections, especially bacterial dysentery[].
Berberine has also shown antitumour activity[].
The plant should not be used with Glycyrrhiza species (Liquorice) because this nullifies the effects of the berberine[].

Other Uses

A yellow dye has been obtained from the roots[].
A purple dye has been obtained from the fruit[].

Propagation

Seed - best sown as soon as it is ripe in a greenhouse[]. It usually germinates in the spring[]. 'Green' seed (harvested when the embryo has fully developed but before the seed case has dried) should be sown as soon as it is harvested and germinates within 6 weeks[]. Stored seed should be sown as soon as possible in late winter or spring. 3 weeks cold stratification will improve its germination, which should take place in 3 - 6 months at 10°c. Prick out the seedlings when they are large enough to handle and grow them on in the greenhouse for at least their first winter. Plant them out in late spring or early summer and consider giving them some protection from the cold for their next winter.
Division of suckers in spring[]. Whilst they can be placed direct into their permanent positions, better results are achieved if they are potted up and placed in a frame until established[].
Leaf cuttings in the autumn.