Hedysarum mongolicum Seeds | Mongolian Sweetvetch
LATIN NAME: Hedysarum mongolicum
COMMON NAME: Mongolian Sweetvetch
Plant Profile
Mongolian sweetvetch is a shrubby perennial of the pea family, native to the sandy steppes, dune margins and dry riverbeds of Mongolia and northern China. It grows sixty to a hundred and fifty centimetres, with upright, woody-based stems, pinnate leaves of small oval leaflets and spikes of pink-purple pea flowers in June and July.
The pods are jointed, breaking into flat, one-seeded segments when they ripen, and each segment is covered with short hairs that catch on fur and clothing. The plant is deep-rooted and long-lived, and its roots carry nitrogen-fixing nodules, so it improves the sand it grows in. It is one of the shrubs used to hold the edges of moving dunes in the Ordos and the Horqin.
Science & Biotechnology
Hedysarum is a genus of some two hundred species, mostly Asian, and it sits in the tribe Hedysareae with the sweetvetches and the sainfoins. Mongolian sweetvetch has been studied mainly for its root system: the taproot goes down two metres or more, and the lateral roots spread widely through sandy soil, which is what makes it useful for stabilisation.
The genus is also known for the compounds in its roots. Hedysarum polybotrys, a close relative, is the source of hong qi, a regional tonic in Chinese medicine, and the flavones and saponins of that species have been investigated for effects on the heart and on the immune system. Mongolian sweetvetch has a similar chemistry but is used far less, and it is mainly a forage and sand-fixing plant.
Uses & Benefits
It is cut for hay and grazed by sheep and goats in the steppe, and it is sown in mixtures for dune fixation, for roadside banks and for the reclamation of sandy farmland that has blown out. It is also a honey plant, and beekeepers move hives to stands in July, when the spikes are in full flower.
In a garden it is a good shrub for a dry, sandy bank, where its deep roots and grey-green foliage cope with drought and its pink spikes feed bees. It needs space, since it reaches a metre and a half, and it is best at the back of a border or in a wilder part of the garden. It is fully hardy and needs no feeding once established.
Growing from Seed
Scarify the seed lightly and soak it overnight, then sow two centimetres deep in a sandy mix at 20-25 °C. Germination is uneven and may take three to five weeks, with some seed waiting until the following spring. Inoculate with the Hedysarum strain of Rhizobium if the ground has not grown this genus before.
Plant out in full sun in poor, free-draining soil, and water through the first summer only. The plant resents wet feet and will die in heavy clay. Cut it back hard in late winter to keep it bushy, and do not feed it with nitrogen, which encourages soft growth at the expense of flowers. It can be raised from root cuttings as well as from seed.
Our Take
A steppe shrub for a dry sandy bank: pink spikes in midsummer, deep roots below, and nitrogen in the soil for whatever follows.
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