Food uses of ferns in China: a review

Wild gathering, together with hunting, used to be the only food source for our ancestors. Although a total of 82 species commodities (or 103 species taxonomically) contribute 90% of national per capita supplies of food plants in the world [1], wild plant gathering is still a tradition that has endured in many local communities [2]. For example, the indigenous peoples of different countries, like Mexico [3], China [4–6], Ethiopia [7], India [8,9], Kenya [10], Palestine [11], and Thailand [12] collect various wild plants for supplementary diets or substitutes for staple food in famine years. Food uses of wild plants are not only common in developing countries, but also in Japan, Europe and North America. For example many wild plants are still consumed in Spain, Portugal and Italy [13–15]. In some European countries, however, the tradition of wild food plant collection and consumption has been lost for generations. In Poland, for example, among over a hundred wild edible plant species recorded, only a few species are still commonly gathered, including two green vegetables, 15 folk species of fruits and seeds and four taxa used for seasoning, or as preservatives. The traditions of use of other species have either been forgotten or are very rarely used [16]. Both American Indians and white people have collected wild vegetables, fruits and mushrooms for consumption, in the United States and Canada [17–19]. In Japan, wild vegetables used to be important food resources in the cold northern parts. Local communities have developed preservation methods including pickling, salting and drying of edible wild plants to be used throughout all the seasons [20]. The number of edible wild plants occurring in Japan is estimated to be over 1000 species [21], or even around 2000 species [22]. However, only around 25 or less species were utilized on a regional scale [23]. Edible ferns are some of the most common wild food plants collected by people around the world. The fern stems, rhizomes, leaves, young fronds and shoots, and sometimes the whole plants are used for food. As early as the 1940s, Athyrium esculentum, Ceratopteris siliquosa, C. pteridoides, Dryopteris prolifera, Pteretis nodulosa, P. esculenta, and Helminthostachys sp. were reported as consumed by the indigenous Filipino [23]. In recent years, more and more research has reported the food uses of pteridophytes in different parts of the world. The fronds of Ophioglossum polyphyllum and those of O. nudicaule are cooked as a vegetable in Nepal. The fronds of Helminthostachys zeylanica are eaten as a salad in rural areas of Malaysia and the Philippines. Tender leaves of Botrychium lanuginosum are regarded as a delicious vegetable in Nepal [24]. Tree ferns have often been used as food and starch in Hawaii [24]. Both young fronds and underground stems of Asplenium ensiforme are used for food in the Himalayas. In Malaysia, the Blechnum orientalis rhizomes are eaten, and the fronds of Ceratopteris thalictroides and Diplazium esculentum are used as vegetables. The rhizome and young shoots of Nephrolepis biserrata are edible. Ophioglossum reticulatum is also eaten as a salad and as a vegetable [25]. In India, stems of Angiopteris sp. are eaten for starch. Pteris ensiformis, Helminthostachys zeylanica, Phymatosorus longissimus and Microsorum alternifolium fern fronds are also used for food. The Maori and Oceanic precedents collected the rhizomes of Petridium esculentum and made food in spring and early Abstract