Comparative vegetative anatomy of Neotropical Goodyerinae Klotzsch (Orchidaceae Juss.: Orchidoideae Lindl.)

Abstract

ABSTRACT The Neotropical genera Aspidogyne and Microchilus (Goodyerinae, Cranichideae, Orchidaceae) comprise ca. 200 rainforests terrestrial species. Although species of Goodyerinae are described with similar anatomy to other taxa of Cranichideae, some anatomical characteristics appear to be specific to the subtribe. Our goal was to characterise the anatomical structure of the vegetative organs of Aspidogyne and Microchilus to identify specific characters of Goodyerinae. Root, stem and leaf samples from eleven species were analysed using light and scanning electron microscopy. The leaves are hypostomatic and glabrous with predominantly anisocytic or tetracytic stomata, thin cuticle, homogeneous mesophyll with chromoplast and raphides, and collateral vascular bundles with parenchyma sheath and collenchyma in the midrib. Spiranthosomes were cofirmed for all species and some specific characteristics were identified in the root, such as the presence of collenchyma in both the cortex and the stele, vascular tissue with fibre-tracheids in the centre of the vascular cylinder, and the presence of a true endodermis with Casparian strips in the stem. Therefore, the root and stem were the organs that showed more taxon-specific characteristics for Goodyerinae, which can be used to better delimited the subtribe.

Keywords

• Aspidogyne
• jewel orchids
• Microchilus
• neotropical orchids
• vegetative anatomy