Tragopogon porrifolius is a plant cultivated for its ornamental flower and edible root. It also grows wild in many places and is one of the most widely known species of the salsify genus, Tragopogon. It is commonly known as purple or common salsify, oyster plant, vegetable oyster, Jerusalem star, Jack go to bed, goatsbeard or simply salsify.
Origin and distribution
Tragopogon porrifolius is a common biennial wildflower, native to southeast Europe and north Africa, but introduced elsewhere, for example, into the British Isles, other parts of northern Europe, North America, and southern Africa and in Australia. In the United States, it is now found growing wild in almost every state, including Hawaii, except in the extreme south-east.
Morphology
The plant grows to around in height. As with other Tragopogon species, its stem is largely unbranched, and the leaves are somewhat grasslike. It exudes a milky juice from the stems. The taproots can become 6–12 in. long and 1–2 in thick. In the UK it flowers from May to September, but in warmer areas such as California it can be found in bloom from April. The flower head is about across, and each is surrounded by green bracts which are longer than the petals. The flowers are like that of Tragopogon pratensis, but are larger and dull purple, across. The flowers are hermaphroditic, and pollination is by insects. The fruits are ockery achenes, rod-shaped and with light ribs. They have a length of 10-17mm and a width of 1-3mm without counting the beak. When going to fruit, a ball of fluff gives the plant its name "goatsbeard".
Cultivation
The root and the young shoots of T. porrifolius can be eaten. The freshly grown leaves can be eaten cooked or raw. Historically, the plant was cultivated for that purpose; it is mentioned by classical authors such as Pliny the Elder. Cultivation in Europe began in the 16th century in France and Italy. In the United Kingdom it was initially grown for its flower and later became a mildly popular vegetable in the 18th century but then declined in popularity. Presently the root is cultivated and eaten most frequently in France, Germany, Italy and Russia. However, in modern times it has tended to be replaced by Spanish salsify as a cultivated crop. Cultivated varieties include 'White French', 'Gian French', 'Mammoth Sandwich Island', 'Improved Mammoth Sandwich Island', 'Blauetikett', and 'Lüthy'; they are generally characterised by larger or better-shaped roots. To maintain the purity of the cultivar a distance of 500 ft has to be met. When T. porrifolius is grown for seed, it is harvested in the second season from midsummer to early autumn to select for bolt resistance. The root becomes discolored and spoils quickly if broken, which can easily happen since it is difficult to remove from the soil without damage.
Salsify is grown similarly to other root vegetables like parsnip and carrots and thus require similar attention. Sowing can be done in late summer or early winter to foster an early growth. Planting can also be done in early spring about 100 days before the first frosts in a well prepared soil, preferably a loam or silt-loam. It should be done at the depth of 1.3 to 2 cm. Spacing between rows should be around 45 to 60 cm and the seeds should be separated by 3 cm approximately. This represent 12 g of seeds per 10 m of row for the cultivar 'Mammoth Sandwich Island'. A thinning to 5 cm between the plants is needed when the seedlings reach 5 cm. T. porrifolius needs deep and loose soils which are not too dry for a good development of the taproot. Stony or waterlogged soils have negative effects on yields and hamper harvesting. Other root crops, legumes and cereals have been mentioned as possible preculture. T. porrifolius is a moderate feeder, therefore the application of fresh manure does not benefit yields. During the main growing period a good water supply prevents potential branching of the taproot.
Climate requirements
There are no specific requirements known for the cultivation of T. porrifolius, but they have been successfully cultivated in temperate climate zones. The seedlings need a temperature between 8-16 °C to germinate and the plant will freeze between -1.1 and -1.6 °C. T. porrifolius can cope with low temperatures and is not injured by light freezing.
Growth and development
The seeds need 8–10 days of germination time. T. porrifolius is a biennial plant. In the first year only the vegetative parts of the plant are developed. In autumn, the energy is stored in the root system, which is depending on the variety more or less branched. In the second season the generative purple flowers envolve. They bloom from early to mid summer.
Harvest and storage
The harvest of the taproots should be from late autumn on and during winter. Harvesting after a frost is favouring the taste of the root. After the flowering, the taproot becomes stringy and inedible. The taproots can be stored in traditional clamps, refrigerated storage was recommended at 0 °C and 90-95% relative humidity for 2–4 months.
Pests and diseases
Pests and diseases affecting T. porrifolius are rather scarce. When the roots are let in the ground during the winter period mice and root voles nibble on it. When the rows are planted too narrow, powdery mildew can affect the plant. The white rust of salsify is the most common diseases on T. porrifolius. Closely related wild species, black salsify, Gerbera and sunflower are also found to be hosts of this pest. In an early stage chlorotic spotting is visible on leaves and stems. They develop during the course of disease into small white blisters. Occasional problems are reported with rust diseases namely Puccinia hystericum, Puccinia jackyana and Puccinia scorzonera. Mulching with oats, and the use of spring vetch or tansy phacelia as cover crops reduces the number of fungi infecting seedlings and roots. The following fungi were isolated from T. porrifolius seedlings and roots: Alternaria alternata, Fusarium culmorum, Fusarium oxysporum, Penicillium spp., Rhizoctonia solani and Sclerotinia sclerotiorum.
As food
The root is noted for tasting of oysters, from which the plant derives its alternative name of oyster plant; young roots can be grated for use in salads, but older roots are better cooked, and they are usually used in soups or stews. It is recommended that when using the root that, if cut, its color be preserved in acidulated water. A latex derived from the root can be used as a chewing gum. The flowering shoots can be used like asparagus, either raw or cooked, and the flowers can be added to salad, while the sprouted seeds can be used in salads or sandwiches.
T. porrifolius contains polyphenol phytochemicals which are under preliminary research for their potential biological effects. Tragopogon species are being studied at the biochemical level for their novel enzyme forms and genetic polymorphism.
