Pseudopodospermum hispanicum, commonly known as black salsify or Spanish salsify, also known as black oyster plant, serpent root, viper's herb, viper's grass or scorzonera, is a perennial species of plant in the sunflower family (Asteraceae), cultivated as a root vegetable in the same way as purple salsify (Tragopogon porrifolius), also in the sunflower family. It is native to Southern Europe and cultivated as a crop in Southern and Central Europe. It grows on nutrient poor soils, dry pasture, rocky areas, in thickets and on limy or marly soils of temperate zones. The flower-head is terminal and consists of yellow ray florets. The stem is smooth and leafy and the leaves are lanceolate to ovate with entire margins. Black salsify forms a long cylindrical taproot with a brownish to black cork layer. If harvested young, the carrot-like roots are tender, long and tapered with shiny white flesh. By 1683, the use of the root as a garden vegetable is recorded in England.
thumb|Black salsify roots
Preparation
Various parts of the plant can be consumed, including roots, leafy shoots, and open flowers, either cooked or raw.
The thick black skin of the salsify root is usually considered inedible and can be removed either prior to or after boiling. If the skin is removed prior to boiling, the peeled root should be immediately immersed in water mixed with vinegar or lemon juice, in order to prevent discolouring. Since the root contains an extremely sticky latex, it is often more convenient to peel it after boiling the root for 20 to 25 minutes (or less). Residue of the latex can be removed by rubbing with a drop of oil and then washing with soap.
Black salsify is often eaten together with other vegetables, such as peas and carrots. But it is also popular served like asparagus in a white sauce, such as bechamel sauce, mustard sauce or hollandaise sauce. Boiled salsify roots may also be coated with batter and deep fried.
The young roots are used in salads and the salsify latex can be used as chewing gum.
Cultivation
thumb|Commercial production in Germany
Black salsify is hitherto mainly a European crop. Belgium, France and the Netherlands are the world's largest producers of black salsify; significant amounts are also produced in Germany. Some other cultivars are commercially available, but because it was a rather localized crop before being produced for a wider market there are comparatively few landraces. Collections of local races and old cultivars can be found at the Nordic Genetic Resource Center in Sweden and the Vavilov Institute of Plant-Genetic Resources in Russia.
{| class="wikitable"
|+ Table 1: Three common black salsify cultivars and their attributes
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! Cultivar !! Attributes
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| Hoffmanns Schwarzer Pfahl ||
- tried and tested
- good storage
- easy harvest
|-
| Duplex ||
- high yield
- long and straight roots
- great taste
|-
| Einjährige Riesen ||
- long, straight, black roots
- easy to harvest
- nice flavor
|}
Breeding objectives are reduced susceptibility to bolting, low percentage of roots with cavities, improved suitability for mechanical sowing and harvesting, as well as for industrial processing. Sowing too early can result in early flowering and loss of yield. About 12 kg of seeds per hectare are required. The seeds are sown directly into shallow furrows at a depth of 1.5 – 2 cm with 30–50 cm in between them. Plants should stand at a density of 50 plants/m<sup>2</sup> for optimal yield. Because of the seeds’ unusual shape, machine sowing is difficult. Storage of seeds is also a critical point, as germination is usually only guaranteed for 1–2 years. Optimal storage conditions are dry and cool. Generally, the species can grow in a variety of conditions and has potential to be grown as a cash crop in less favorable, marginal environments in temperate zones.
Harvesting and post-harvest treatment
Harvesting takes place from November to March, with the optimum time for high quality being end of December. and will grow well in most cool-temperate climates and usually yield 15–20 tonnes of roots per hectare. In British gardens it is common to profit from its perennial character by leaving it in the ground until its roots have grown to sufficient size for harvesting; this can take two years. Commercially, it can be grown best as the year's second crop. It is recommended to have three to four years in the crop rotation before the cultivation of other Asteraceae.
Pests and diseases
Pests
- Carrot rust fly (Psila rosae): The larvae or maggots of the carrot rust fly eat the plant roots and entrench themselves in the roots. Psila thereby inhibits plant growth and facilitates infection by soft-rot bacteria. Generally root crops are popular for the carrot rust fly.