Triuridaceae

Ecology

The Triuridaceae are a small family (c. 6 genera, and c. 45 spp.) of very delicate, saprophytic, terrestrial, mostly dark-red coloured herbs growing in the deep shade of everwet tropical forest, entering the subtropics only in Japan and the Bonin Is. They are in Africa confined to restricted areas in the West and includes part of East Africa (see Kew Bull. 36 (1982) 733), and are also in continental Southeast Asia remarkably rare, as yet only known from two localities in Assam and N. Thailand respectively. . The nearest localities to Indochina and China are in Hainan and Botel Tobago Is. (southeast off Taiwan). In Australia they are only found in the Bellenden Ker Range in NE. Queensland, showing their aversion to dry and seasonal climates.

By their small stature (10-40 cm), dark colour, and very small flowers they are evasive to collectors; the only one reaching some size (45-140 cm) is Sciaphila purpurea which is found in Peru, according to GIESEN mainly in termite nests in hollow trunks. During exploration, trip stops, either for felling or climbing trees, or for culinary or sanitary purposes, offer the best opportunity to observe them.
Flowering specimens can probably be found throughout the year, as it appeared that of common species such as Sciaphila arfakiana, specimens have been collected in all months of the year.

Taxonomy

Formerly Triuridaceae were usually placed in the affinity with Liliaceae by BENTHAM& HOOKER and by ENGLER& PRANTL. HUTCHINSON (1934) raised the family to the order Triuridales, alongside Alismatales to which he also reckoned the saprophytic genus Petrosavia, which usually was accommodated in Liliaceae, but deviates from Liliaceae in having an apocarpous gynoecium. He recognized Petrosavia as representing a distinct family Petrosaviaceae.
Recently this controversial matter was further elaborated by CRONQUIST (1981), who also recognized Triuridaceae in the rank of an order, Triuridales, but more closely associated Petrosaviaceae with Triuridaceae and finds 'the resemblance so complete that I would have no hesitation in placing Petrosavia in the family Triuridaceae on the basis of anatomical evidence.' This view is shared by DAHLGREN& CLIFFORD (1982). The removal of Petrosavia from Liliaceae to the affinity of Triuridaceae is here also supported by MULLER (vide infra) who found that the pollen of Triuridaceae shows some similarity to that of Petrosavia and Vallisneria and does not suit that of Liliaceae.
The family was meticulously revised by H. GIESEN (1938) who had the rich material (much on liquid) of Herbarium Bogoriense. In addition, the great value of his work is the fact that he reported in detail on many type specimens, of which some in Berlin are now lost and also on those of Florence, which were not sent to me on loan. This enabled me to reach a satisfactory interpretation.
From Malesia GIESEN had some 130 collections at his disposal. The present revision is based on 300 collections. This increase led to a better insight in the variability of characters and made it possible to select those that are reliable, which in turn led to a rather heavy reduction in the number of species and more critical generic and specific delimitations.
As to the genera, Sciaphila (incl. Andruris) is by far the largest (c. 35 spp.), and covers the entire range. Three small genera (1 or 2 spp. each) are neotropical, a fifth is confined to the Malagasian area, and the sixth is endemic in the Deccan and Ceylon; both are monotypic.

Synonymy

Triuridaceae