Amphineuron terminans (PROSEA)
Amphineuron terminans (Hook.) Holttum
- Protologue: Amer. Fern Journ. 63: 82 (1973).
- Family: Thelypteridaceae
- Chromosome number: 2n= 144 (tetraploid)
- Nephrodium terminans Hook. (1862),
- Cyclosorus interruptus sensu Holttum (1955),
- Thelypteris terminans (Hook.) Tagawa & K. Iwatsuki (1975).
- Philippines: lokdo.
Origin and geographic distribution
A. terminans is distributed from southern India, Sri Lanka and southern China (Hainan, Macao) throughout South-East Asia to Australia (Queensland to 18°S). Sporadically, it has also been found in Central Africa and Fernando Poo.
In some parts of the Philippines, the stems of A. terminans are crushed and the vascular strands extracted for use as decorative weaves in baskets.
The vascular strands of A. terminans which are used for decorative weaves in baskets are of inferior quality and are not strong.
Rhizome long-creeping, 5 mm in diameter (dry); scales narrow, setiferous, up to 6 mm long, brown. Leaves tufted, pinnately compound; petiole up to 50 cm long, flushed dull reddish, minutely hairy, glabrescent abaxially, basal scales about 8 mm long; lamina subelliptical in outline, up to about 80 cm × 40 cm, pinnate, apex similar to the lateral pinnae or somewhat broadened and few lobed at the base; abaxial surfaceof costae, costules and veins bearing short acicular hairs, longer hairs usually lacking; subsessile, almost spherical, rather pale glandular hairs abundant on distal veins, usually few and smaller on lower veins; very short acicular hairs often present between veins; adaxial surface of costae bearing antrorse pale acicular hairs, similar hairs scattered on costules and veins, some hairs also on surfaces in exposed plants; copious, small, yellow glands present along veins near segment margins; up to 25 pairs of pinnae; rachis bearing short acicular hairs; pinnae oblique, always distinctly narrowed at their bases, 17-20(-29) cm × 1.7 cm, if longer not more than 2 cm wide; basal pair somewhat reduced, rarely very small; base of middle pinnae broadly cuneate to truncate, lobed 1/3 towards costa or less deeply, apex acuminate; lobes as wide as long or wider with forward pointing tip, apex broad asymmetrical; venation costules 4-5 mm apart, usually at a less than 60°angle to costa; veins 6-9 pairs, basal pairs spreading at a broad angle to their costules and always anastomosing, uniting to form a rather long excurrent vein to the sinus; next veins very oblique; 1 or 2 ending beside the sinus-membrane. Sori orbicular, supramedial, confined to the upper veins, thus occupying only the lobes of the pinnae leaving a broad sterile zone on either side of the costa; indusium reniform, persistent, setulose , large, thin, often with some short acicular hairs and a few small, yellow, glandular hairs which are not marginal. Spores dark, irregularly rugose or with irregular thick and more or less branched ridges.
Growth and development
The gametophyte of A. terminans is symmetrically cordate, with on all parts unicellular chlorophyllous hairs with swollen, rounded tips that become wax-encrusted.
Other botanical information
The family Thelypteridaceae has no close living relatives and its affinities are not known for certain. Some authors have argued that the family is closest to the genus Cyathea J.E. Smith because of several common characters. Others, however, have pointed to other contradictory characteristics. Cladistic research based on morphological as well as molecular characters strongly support the relationship with the polypodioid ferns. The taxonomy of the family is confusing because there are many different opinions about the number and delimitation of genera. Here the Flora Malesiana (Holttum) view is followed, in which the family is subdivided into 25 genera (for the Old World species). Often the differences between genera are vague and include characters of minute glands and hairs, requiring 30 × magnification or greater for observation. Moreover, hybrids between genera seem to exist (having intermediate characters of the genera), which would favour a much wider genus concept. Amphineuron Holttum comprises about 12 species, all occurring in South-East Asia; other authors include Amphineuron in Cyclosorus Link or in Thelypteris Schmidel. Amphineuron is closely related to the genus Christella Léveillé (about 50 species, distributed in tropical Asia and Africa). The two most widely distributed Amphineuron species, A. terminans and A. opulentum (Kaulf.) Holttum, are both variable and have a complex nomenclatural and taxonomic history. They probably also hybridize (possible examples have been found in Thailand). A. opulentum seems to be adapted to semi-exposed locations among rocks, especially in areas with a dry season; it can be distinguished from A. terminans by its shorter creeping rhizome and its pinnae that are lobed more than halfway to the costa.
A. terminans is a terrestrial fern, common in thickets on hillsides, in localized wet patches along river banks and in valleys at low and medium altitudes. It occurs abundantly in areas with a distinct dry season, in rather open but not too dry locations.
Propagation and planting
Although A. terminans is hardly cultivated commercially, it can be propagated by spores, and more easily by rhizome cuttings. In natural habitats it spreads quickly due to its long creeping rhizomes. The plants can be grown in large pots but are best suited to culture in the field.
Genetic resources and breeding
Its wide distribution and abundance in certain habitats more or less guarantees the survival of A. terminans , for which neither germplasm collections nor breeding programmes are known to exist.
It is not expected that A. terminans will become more important in the future; possibly its ornamental value deserves better investigation.
- Holttum, R.E., 1966. A revised flora of Malaya. 2nd Edition. Vol. 2. Ferns of Malaya. Government Printing Office, Singapore. pp. 262-264.
- Holttum, R.E., 1982. Thelypteridaceae. In: van Steenis, C.G.G.J. & Holttum, R.E. (General editors): Flora Malesiana, Series 2. Pteridophyta (Ferns & fern allies). Vol. 1, part 5. Martinus Nijhoff / Dr W. Junk Publishers, The Hague, The Netherlands. pp. 545-547.
- Smith, A.R., 1990. Thelypteridaceae. In: Kramer, K.U. & Green, P.S. (Volume editors): Pteridophytes and gymnosperms. In: Kubitzki, K. (Series editor): The families and genera of vascular plants. Vol. 1. Springer-Verlag, Berlin, Germany. pp. 263-272.
- Zamora, P.M. & Co, L., 1986. Economic ferns, endemic ferns, gymnosperms. In: Umali, R.M. et al. (Editors): Guide to Philippine flora and fauna. Vol. 2. Natural Resources Management Center, Ministry of Natural Resources and University of the Philippines, Quezon City, Philippines. p. 34.
W. P. de Winter