Holboellia latifolia Seeds | Blue Sausage Fruit
LATIN NAME: Holboellia latifolia
COMMON NAME: Blue Sausage Fruit
Plant Profile
Blue sausage fruit is an evergreen twining climber that will run three to six metres up a wall, a tree trunk or a sturdy pergola, and it does so with a quiet, dense persistence rather than with the flamboyance of a clematis. The leaves are palmate, made up of three to seven leathery leaflets, each one glossy dark green above and paler beneath, with a wavy margin and a network of pale veins. The stems are slender and twine tightly, and the plant builds a thick curtain of foliage that is handsome all year and useful for screening.
The flowers appear in early spring, in short races hanging from the leaf axils, and they are the plant’s best-kept secret. The species is monoecious, with small greenish-purple male flowers and larger, deeper purple-brown female flowers on the same plant, and the whole cluster has a faint, sweet, spicy scent. They are followed by the fruits that give the plant its name: long, cylindrical, slightly lumpy berries, five to ten centimetres long, which turn from green to blue-violet with a white bloom as they ripen in autumn. Inside, the pulp is pale, soft and sweet, surrounding dark seed, and it is edible when fully ripe. The species is native to the forests of the Himalaya and southwestern China, from Nepal and Bhutan through Yunnan and Sichuan, generally between twelve hundred and twenty-seven hundred metres.
Science & Biotechnology
Holboellia sits in the Lardizabalaceae, a small family of vines and shrubs that also includes Akebia, Stauntonia and Decaisnea, and the group is of interest because its floral structure is unusual among the eudicots. The flowers have six tepals in two whorls, and the male and female flowers differ in the way the stamens and carpels are arrested during development, which makes the family a useful subject for studies of sex determination in plants. Molecular work has clarified the relationships within the family and confirmed that Holboellia is close to Stauntonia, with which it is sometimes confused in cultivation.
The fruit has been examined for its pigments, which are anthocyanins responsible for the blue-violet colour, and for its sugar and organic acid profile, which is mild and low in acidity compared with most berries. Seed biology is the practical difficulty: the seed has an underdeveloped embryo and a tough coat, so it needs a period of cold, moist stratification and germinates slowly and unevenly. There is also a safety point worth making about the family. Akebia, a close relative, is the source of the Chinese drug Mu Tong, which has been associated with aristolochic acid nephropathy when adulterated or substituted, and although Holboellia is not implicated in that, the confusion is a reminder that the family contains both food plants and medicinal ones that must not be mixed.
Uses & Benefits
The fruit is the reason the plant is grown in its native range, where it is collected from the wild and eaten fresh. The pulp is sweet and mild, with a texture somewhere between a melon and a custard apple, and it is best when the fruit is fully coloured and slightly soft; picked early, it is bland and astringent. It does not travel well and is rarely seen in markets outside the region. In the garden the vine is grown as an ornamental and a screen, and it is one of the best evergreen climbers for a north or east wall, since it tolerates shade and does not mind root competition.
The plant is also useful for covering an unsightly structure quickly, and it can be trained along a fence or through a large shrub. It is not invasive in the way that some vines are, and it responds well to pruning after flowering, which keeps it within bounds and encourages flowering wood. In cool climates it is hardy to about minus fifteen degrees once established, though late frost can damage young growth. It is a plant for a woodland garden or a shaded boundary rather than for a hot, sunny border.
Growing from Seed
Sow fresh seed, cleaned of pulp, into a mix of leaf mould, coarse sand and loam, and give it four to six weeks of cold, moist stratification at four degrees before moving it to fifteen to eighteen degrees. Germination takes four to ten weeks and is uneven. Keep the mix moist but not wet, and shade the tray from direct sun. Seed that has been dried and stored is much slower and may not come up at all, so freshness matters more than technique.
Prick the seedlings out into deep pots once they have two true leaves, and give them a cool, shaded frame for their first year. Plant out in spring or autumn into humus-rich, well-drained soil, with the root in shade and the top in light, and provide a support from the start. Mulch thickly to keep the roots cool and moist, and water through the first two summers. Prune after flowering to keep the vine within its space, cutting back the oldest stems to the base every few years to encourage new growth. Several plants are needed for reliable fruit set, since the flowers are not self-fertile.
Our Take
A quiet, useful climber rather than a showstopper, and all the better for it. Give it shade at the root, a support to climb and a little patience, and it will fruit in the third or fourth year.
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