Abstract
Hypoxidia (Hypoxidaceae) is endemic to the Seychelles islands. The two species H. rhizophylla and H. maheensis have rarely been studied. The first studies of floral ecology are described based on 19 years of observations of cultivated (1992–1994) and wild (1998–2011) plants of H. rhizophylla and a single flowering event of cultivated H. maheensis. In H. rhizophylla, heavy rainfall acts as a trigger to flowering, with flowers opening 14 days after heavy rain. This can occur in any month and local rainfall can act as a trigger even in generally dry conditions. Flowers are only open for a few hours, usually in the morning. Pollinators have not been identified but only one specie has been seen visiting flowers regularly; the fly Dichaetomyia fasciculifera (Muscidae) is common on Silhouette island where 12% of flowers are pollinated but very scarce on Mahé where fruiting of H. rhizophylla is rarely recorded. Low rates of pollination and limited dispersal is thought to result in effective isolation of most populations which probably mainly reproduce clonally. Clarification of this requires further research into genetic structuring of the populations.
Highlights
Hypoxidia is an isolated genus of the family Hypoxidaceae
The Seychelles Hypoxidaceae are unusual in that they can be argued to form a major part of the forest ecosystems, being among the few herbaceous plants to be found in the closed woodlands of the larger Seychelles islands
H. rhizophylla is highly variable in leaf shape and size but always shows the ability to reproduce with epiphyllous buds
Summary
Hypoxidia is an isolated genus of the family Hypoxidaceae. It comprises two species, restricted to the Seychelles islands and forms a monophyletic Seychelles clade with the species “Curucligo” seychellensis [1]. Friedmann is the most widespread of the Seychelles Hypoxidaceae, being recorded from Mahe, Silhouette, Praslin, La Digue, Curieuse, and Felicite [2, 3] On these islands it is rarely found below 150 m a.s.l. but can be found from sea level to 900 m a.s.l. H. rhizophylla is highly variable in leaf shape and size but always shows the ability to reproduce with epiphyllous buds As a result it frequently forms what are probably clonal clumps. A high degree of geographical variation in floral characters has been observed in H. rhizophylla [4, 5], at least some of this variation appears to be genetic (being retained by cultivated plants), but whether these differences represent geographic genetic structuring or individual variation of clonal populations is not known. Ecological reports are limited to observations of their habitats [5, 9] and observation of synchronous flowering [10]
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