Anatomy of the invasive orchid Oeceoclades maculata: ecological implications.
Oeceoclades maculata is the most successful invasive orchid in the Neotropics. The anatomy of the vegetative organs, peduncle and seeds of O. maculata was characterized to identify features of possible physiological and ecological importance. Plants from four locations in Soconusco, Chiapas, Mexico were selected. Transverse, longitudinal and paradermal sections of vegetative organs were observed using light and scanning electron microscopes. Oeceoclades maculata has amphistomatous leaves, with smooth and a thin to slightly thickened cuticle, a single-layered epidermis, a low density of small stomata (<13 mm-2) and numerous sunken glandular hairs on both surfaces. Mesophyll is homogeneous with abundant extravascular fibre bundles. The root has a multilayered velamen with abundant tilosomes. Numerous idioblasts with raphides were observed in leaves, pseudobulbs and roots. The seeds are fusiform, with smooth surfaces and transverse folds. Some of these traits link O. maculata with terrestrial and epiphytic habits and with xerophytic habits, with humid and high light intensity and humid environments. This combination of traits might be a key factor behind the success and expansion of O. maculata. Nonetheless, a detailed characterization of the microhabitats occupied, demography, reproductive strategies and mycorrhizal associations will be essential for understanding the behaviour of this invasive species and, if necessary, designing strategies for its control.