Other names: Local names: hak tin houng,pak sin hung, pak din khii khep, kud nok yung. Thai:kut chong, kut din khouang, kut tin hung, kut sang, tin nok yung, pak nok yung, tu yu la ngi. Vietnamese: quan trong, sam dat rang reung gie, sam bong bong. Chinese: gan zhong, di wu gong. English: fern.
Use: Roots are used in traditional medicine to treat dysentery, also in China and Taiwan where they are used to “cool down the body” (ya yen), and against malaria. Young shoots and young flowers are edible as greens.
Active ingredients:Good source of phosphorus, calcium and iron.
Harvesting: Roots/rootstock is dug out when shoots sprout and the plants become visible. It probably takes 2-3 years to reach minimum harvesting size of 10 cm root length, optimal harvesting size is 30 cm.
Yields, densities: Fresh roots of 160 plants weigh 1 kg. 3 kg of fresh ferns or 500 plants produce 1 kg of dried ferns. Average density found in collection sites was 700 plants/ha. Wild plants yields perhaps 1.5 kg/ha of dried roots. In cultivation, densities of 30 x 30 cm are possible and yield around 220 kg/ha.
Access rules: Natural, open access.
Sustainability:Harvesting destroys the plant, but the upper part of the rhizome can be replanted. Present harvesting intensity leads to rapid depletion. However, it was found that the density of surviving young plants (1,200 plants/ha) was larger than the amount of plants harvested – 700 plants/ha. The high density of young plants seems to indicate that there is active regeneration. It is not known how many of these young plants are produced from leftover rhizomes or from spores. It is possible to harvest the older part of the rhizome with adjacent roots and replant the remaining top part with the active growing buds.
Conservation status: Propagation: Propagation is probably possible by rootstock or by spores has not been tried yet. Transplanting rhizomes in moist, shaded garden tried successfully, and roots can be harvested in 2-3 years.
Enrichment planting of rootstocks in the forest and/or planting bamboo and ferns in agroforestry gardens.
Processing: Sun drying is done at village level.
Quality criteria:The roots should be clean, dry and intact.
Marketing: Commercial exploitation in Lao PDR started sudden in 1995, with stable Chinese demand. Price per kg in 1998 was US$2.3. After 2000 no quotas were given out, possibly due to depleted fern root resources. In China tinhoung is sold in single herb extracts for US$14.5/100 gram. A Chinese medicine shop in the USA was found on the internet offering di wu gong for US$153.00/kg.
Market prospects: Because harvesting is so depletive, prices may go up. Prospects for commercial plantation seem good with possible yields of US$500-1,000 per ha. Propagation techniques need to be developed.
Description: Small erect annual ground fern, 20-50 cm. Leaves lobed pointed, growing in 2 rows, terminal palmate, 5-25 cm by 10-50 mm, tripartate. Inflorescence glabrous, tubular, green and erect, yellowish-green 10-15 cm long, spores white-green. Rhizome, creeping, up to 7 mm in diameter, bearing numerous fleshy roots and a front in each year. Lateral roots grow from the rhizome resembling the legs of a millipede din khii khep.
Distribution & Ecology: Often found under Bambusa arundinaceae (mai phai pa), B. tulda (mai bong) and Bambusa sp. (mai ko) in wet, shaded places near streams, ponds or marshes, in loamy clay soils. It is not clear whether this is an obligatory symbiosis or simply that both species prefer the same habitat. The tuberous prothallus grows subterraneous as a saprophyte, dependent on a fungus. Hak tin houng is found in most of the lowlands, from Vientiane to Attapeu. Found all over SE Asia.