Lycium ruthenicum Seeds | Black Goji
LATIN NAME: Lycium ruthenicum
COMMON NAME: Black Goji
Plant Profile
The plant is a low, stiffly branched shrub, usually under a metre in the wild, with narrow fleshy leaves bundled on short shoots and slender spines along the older wood. Flowers are borne singly or in pairs, funnel-shaped with five violet lobes, showing the family plainly in their fused corolla and protruding stamens. Fruit is a small glossy black-purple berry with a handful of tiny flattened seeds.
The red wolfberry of Ningxia is a bigger, sweeter berry whose colour comes from carotenoids, chief among them zeaxanthin dipalmitate. The black species is smaller and less sweet, wild-harvested across the deserts and salt flats of the northwest, and coloured by an entirely different class of molecule. Both are thorny shrubs that fruit on the current season’s growth.
In acid solution the pigment reads red-violet; as pH rises it shifts toward blue, which is why the same fruit dyes lemonade pink and a neutral drink a dull slate blue. Acylated anthocyanins also resist fading during heating, and that stability is the commercial argument for using black goji extracts in beverages. Extraction is usually done with acidified water or a water-alcohol mixture.
Science & Biotechnology
The principal anthocyanin of the fruit is petanin, a petunidin glycoside whose sugar chain carries a p-coumaric acid residue. That single acyl group is what makes the pigment so stable: acylated anthocyanins hold colour against heat, light and small shifts in pH far better than the simple glucosides of a raspberry. Chlorogenic acid, rutin and polysaccharide fractions account for most of the rest of the fruit’s studied chemistry.
Uses & Benefits
Most dark fruit is dark only in its skin. Crush a black goji berry and the juice itself is deep violet, because the pigment sits in the flesh too, and a handful in hot water turns the cup to a dark purple infusion within a minute. That property has taken the plant from a thorny desert shrub to a traded crop.
Most of the crop is dried and sold as a berry for infusion, and it travels well because the skin is thick and the seeds are small. The dried berry is also milled as a colouring ingredient, where its pH sensitivity is either the point or the problem. Demand is met largely from wild stands, and cultivation has been expanding on marginal saline land.
For a drink, steep a small spoonful of dried berries in hot water until the liquid turns deep purple; a squeeze of lemon sharpens the colour toward pink, a pinch of soda dulls it toward blue. The same infusion colours rice and desserts without adding much flavour beyond mild acidity. Fresh berries are edible but seedy and bland.
Growing from Seed
Black goji grows where few crop plants will: saline-alkali flats, gravel plains and the edges of sand dunes with a high water table and a long dry season. It survives by taking sodium into the vacuole rather than excluding it, and by adjusting osmotically with soluble sugars and free proline. Deep roots reach moisture below the surface, and its suckering habit helps fix moving sand.
The seeds are small and the seedlings slow, so they are best started in pots and planted out once the stems have stiffened.
A sandy loam with a high pH suits this species better than rich neutral garden soil, and it will grow where lime has been spread or drainage is sharp. Add grit if the bed holds water, because waterlogged winter soil kills more plants than frost. In a container, use a sandy mix and let it dry between waterings.
The shrub fruits on young wood, so an annual tidy pays: cut out a quarter of the oldest stems at the base and shorten long arching shoots in late winter. Suckers appear freely from the roots and can be lifted with a spade as new plants. Gloves are worth wearing, since the thorns are small and stiff.
Coming from continental cold deserts, black goji takes hard winter cold and long dry spells without complaint, and it needs little water. Aphids and psyllids gather on soft growth, powdery mildew appears in still air, and as a solanaceous plant it can carry viruses that also affect tomatoes and potatoes.
Our Take
I grow black goji for the colour of the infusion and the fact that it asks for nothing. Sow it in a sandy mix and plant the seedlings on a hot, limey bank where nothing else thrives. For comparison, the red fruiting species and its relatives are worth a look in Lycium chinense and Lycium berlandieri, while the salt-flat planting idea is taken further by the crystalline ice plant.
Related Reading
More species in the same orbit as Black Goji: