Orchid Biology: Darwin`s Contrivances 150 Years Later
Carlsward, Barbara .
Vegetative anatomy of Orchidaceae: How I stopped worrying about losing my fingers and learned to love the microtome in the era of molecular phylogenetics.
Vegetative anatomy has been utilized for over a century as a systematic tool in Orchidaceae. There are several anatomical features found in leaves and roots that are systematically useful in diagnosing large clades. These include features such as the presence of stegmata and shape/texture of their included silica bodies; presence and form of tilosomes associated with passage cells of the exodermis; presence and distribution of fiber bundles in leaves and stems; configuration of the mesophyll; and patterns of wall thickenings in cells of the exodermis and endodermis. As anatomically diverse as Orchidaceae are, though, they show many constants in their vegetative anatomy. Among the epiphytic taxa, for example, these constants include: adaxial epidermal cells of leaves larger than abaxial epidermal cells; collateral vascular bundles in leaves and stems; velamen cell walls marked by various thickening patterns; unicellular root hairs; heterogeneous root cortex; thick-walled longcells of the exodermis; raphide bundles in idioblasts; when present, stegmata appearing alongside sclerified cells (e.g., fibers); and walls variously thickened in water-storage cells scattered throughout the ground tissues. In spite of these consistencies, there are other diagnostic anatomical features yet to be assessed and applied where appropriate in outlining the systematics of Orchidaceae.
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1 - Eastern Illinois University, Department Of Botany, Life Sciences Bldg. 2070, 600 Lincoln Ave., Charleston, IL, 61920, USA
Presentation Type: Symposium or Colloquium Presentation
Location: Franklin B/Hyatt
Date: Wednesday, July 11th, 2012
Time: 1:30 PM