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Ophioglossum reticulatum L.

Protologue
Sp. pl. 2: 1063 (1753).
Family
Ophioglossaceae
Chromosome number
n = 240, 360, 480, 510, 435–570, 630
Synonyms
Ophioglossum vulgatum L. var. reticulatum (L.) Luerss. (1875).
Vernacular names
Adder’s tongue fern (En). Langue de serpent, ophioglosse (Fr). Lingua de cobra (Po).
Origin and geographic distribution
Ophioglossum reticulatum is a pantropical species that is widespread in tropical Africa: from Sierra Leone east to Ethiopia, and south to South Africa. It also occurs in Madagascar and other Indian Ocean islands.
Uses
The leaves of Ophioglossum reticulatum are eaten as a salad or cooked vegetable in Zanzibar (Tanzania). In Indonesia it is locally an appreciated vegetable, collected sedulously wherever it is common. The leaves should be blanched only; if boiled too much they turn into slime. In Madagascar the related Ophioglossum ovatum Bory is eaten boiled, and is especially sought by the Antandroy tribe.
A warm decoction of the rhizome of Ophioglossum reticulatum is used topically in Lesotho on boils. In Tanzania, the leaf juice is drunk against spasms of the heart. A report from Nigeria mentions two useful Ophioglossum species, called Ophioglossum grande and Ophioglossum vulgatum, but these species do not occur in West Africa. The first one possibly refers to Ophioglossum reticulatum, and it is stated that the young fronds are used as fodder for livestock (goats), and that the retted leaves are used as garden manure. Extracts of the rhizomes are used as antidote for snakebites. The second one possibly concerns the other most frequent Ophioglossum in the area, Ophioglossum costatum R.Br. A decoction of the rhizomes of these plants is taken internally to treat lung and heart diseases. The dried and pulverized rhizome is applied externally to sores, wounds and burns.
In the Philippines Ophioglossum reticulatum is used as an anti-inflammatory medicine; leaves boiled in oil are applied to wounds.
Properties
Young leaves of Ophioglossum taste sweet. The presence of alkaloids, arbutin, amygdalin, saponin, formic acid and oxalic acid has been shown.
Botany
Small erect fern 5–30 cm tall, with 1–2 leaves on a 1–2 cm long and about 2 mm thick rhizome with few fleshy roots. Leaves with up to 15 cm long petiole, blade cordate, rarely broadly elliptical or ovate, 3–7 cm × 3–8 cm, apex rounded with or without a small mucro, entire, with prominent anastomosing venation in a polygonal pattern. Fertile part of leaf spikelike, up to 25 cm long, arising from the base of the blade, bearing up to 45 pairs of sporangia in the upper quarter or less, apex acute; sporangia opening by a transverse slit. Spores subglobose, blackish, surface finely reticulate of two types, one alete with a diameter of 42–50 μm, the other trilete and 25–38 μm in diameter.
Ophioglossum reticulatum is quite uniform in Africa and can be satisfactorily characterized by the clearly cordate base of the blade in combination with the absence of a tuber. Worldwide, many varieties and subspecies have been described, causing much confusion. It seems best to regard them as one variable pantropical species.
The plants are only present above ground in the rainy season. They can form stolons and form rather extensive colonies.
Ecology
Ophioglossum reticulatum grows in moist sandy soils, seasonally wet soils, along roads, on termite hills, in montane grassland among rocks and forest margins, from sea-level up to 2500 m altitude.
Management
The plants are collected from the wild and traded locally. Commercial cultivation of Ophioglossum reticulatum is not practised, but for medicinal use it is often grown in pots. It can be propagated from spores and by rhizome cuttings. When grown from spores, plants can be harvested for their leaves after 1–2 years. When grown from rhizomes collected from the wild, harvesting may start after about 6 months. In agriculture it can become a weed, but does little harm because of its small size.
Genetic resources and breeding
Ophioglossum reticulatum is found all over the tropics and is in no danger of genetic erosion. More research on the large variability seems appropriate.
Prospects
Ophioglossum reticulatum has nutritional, medicinal and ornamental value, but it does not seem to be widely used in Africa. Because of the close resemblance of Ophioglossum species and their variability, it may very well be that other species are also consumed or used in similar ways. It seems worthwhile investigating the possibilities of cultivation and breeding.
Major references
• Burkill, H.M., 2000. The useful plants of West Tropical Africa. 2nd Edition. Volume 5, Families S–Z, Addenda. Royal Botanic Gardens, Kew, United Kingdom. 686 pp.
• Decary, R., 1946. Plantes et animaux utiles de Madagascar. Annales du Musée Colonial de Marseille, 54e année, 6e série, 4e volume, 1er et dernier fascicule. 234 pp.
• Haerdi, F., 1964. Die Eingeborenen-Heilpflanzen des Ulanga-Distriktes Tanganjikas (Ostafrika). In: Haerdi, F., Kerharo, J. & Adam, J.G. (Editors). Afrikanische Heilpflanzen / Plantes médicinales africaines. Acta Tropica Supplementum 8: 1–278.
• Nwosu, M.O., 2002. Ethnobotanical studies on some Pteridophytes of Southern Nigeria. Economic Botany 56(3): 255–259.
• Williams, R.O., 1949. The useful and ornamental plants in Zanzibar and Pemba. Zanzibar, Tanzania. 497 pp.
Other references
• Alston, A.H.G., 1959. The ferns and fern-allies of West Tropical Africa. Crown Agents for Oversea Governments and Administrations, London, United Kingdom. 89 pp.
• Amoroso, V.B. & Ong, H.C., 2003. Ophioglossum reticulatum L. In: de Winter, W.P. & Amoroso, V.B. (Editors). Plant Resources of South East Asia No 15(2). Cryptogams: ferns and fern allies. Backhuys Publishers, Leiden, Netherlands. pp. 153–155.
• Burrows, J.E. & Johns, R.J., 2001. Ophioglossaceae. In: Beentje, H.J. (Editor). Flora of tropical East Africa, A.A. Balkema, Rotterdam, Netherlands. 19 pp.
• Khandelwal, S., 1990. Chromosome evolution in the genus Ophioglossum L. Botanical Journal of the Linnean Society 102(3): 205–217.
• Schelpe, E.A.C.L.E., 1970. Ophioglossaceae. In: Exell, A.W. & Launert, E. (Editors). Flora Zambesiaca. Pteridophyta. Crown Agents for Oversea Governments and Administrations, London, United Kingdom. pp. 34–38.
• Tardieu-Blot, M.L., 1964. Ophioglossaceae. Flore du Gabon. Volume 8. Muséum National d’Histoire Naturelle, Paris, France. pp. 29–31.
Sources of illustration
• Amoroso, V.B. & Ong, H.C., 2003. Ophioglossum reticulatum L. In: de Winter, W.P. & Amoroso, V.B. (Editors). Plant Resources of South East Asia No 15(2). Cryptogams: ferns and fern allies. Backhuys Publishers, Leiden, Netherlands. pp. 153–155.
Author(s)
W.J. van der Burg
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
Based on PROSEA 15(2): ‘Cryptogams: Ferns and fern allies’.

Editors
G.J.H. Grubben
Prins Hendriklaan 24, 1401 AT Bussum, Netherlands
O.A. Denton
National Horticultural Research Institute, P.M.B. 5432, Idi-Ishin, Ibadan, Nigeria
Associate Editors
C.-M. Messiaen
Bat. B 3, Résidence La Guirlande, 75, rue de Fontcarrade, 34070 Montpellier, France
R.R. Schippers
De Boeier 7, 3742 GD Baarn, Netherlands
General editors
R.H.M.J. Lemmens
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
L.P.A. Oyen
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
Illustrator
PROSEA
PROSEA Network Office, Herbarium Bogoriense, P.O. Box 234, Bogor 16122, Indonesia

Correct citation of this article:
van der Burg, W.J., 2004. Ophioglossum reticulatum L. In: Grubben, G.J.H. & Denton, O.A. (Editors). PROTA 2: Vegetables/Légumes. [CD-Rom]. PROTA, Wageningen, Netherlands.
1, plant habit; 2, plants connected by stolons; 3, fertile part of leaf.
Source: PROSEA