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

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.

摘要 新热带区的盾柱兰属（Aspidogyne）与小唇兰属（Microchilus）隶属于兰科（Orchidaceae）头蕊兰族（Cranichideae）斑叶兰亚族（Goodyerinae），共计约200种雨林陆生物种。尽管斑叶兰亚族物种的解剖结构与头蕊兰族其他类群相似，但部分解剖特征似乎为该亚族所特有。本研究旨在阐明盾柱兰属与小唇兰属营养器官的解剖结构，以识别斑叶兰亚族的特有特征。本研究通过光学显微镜（light microscopy）与扫描电子显微镜（scanning electron microscopy），对11个物种的根、茎、叶样本展开分析。叶片为下生气孔式（hypostomatic）且无毛，气孔类型以平列型（anisocytic）或四列型（tetracytic）为主，角质层较薄，叶肉组织均质且含有色质体（chromoplast）与针晶束（raphides）；叶脉具外韧维管束，中脉处带有薄壁组织鞘与厚角组织（collenchyma）。所有供试物种均确认存在螺旋体结构（Spiranthosomes）；根部还存在若干特异性特征：皮层与中柱均含有厚角组织，维管柱中央的维管组织具有纤维管胞，茎部则存在带有凯氏带（Casparian strips）的真正内皮层（true endodermis）。综上，根与茎是展现出更多斑叶兰亚族类群特异性特征的器官，这些特征可用于更精准地界定该亚族。