Dendrobium

Pignal, Marc & Munzinger, Jérôme, 2020, Morphological and anatomical investigation of New Caledonian graminoid Dendrobium (Orchidaceae) with the description of two new species, European Journal of Taxonomy 633, pp. 1-26 : 21-22

Key based on leaf anatomy (transverse section) to the graminoid species of Dendrobium in New Caledonia

1. Leaves thick, vascular bundles in two parallel lines, very numerous (> 32), largest with diameter <½ the thickness of the leaf blade ......................................................................... D. crassifolium Schltr.

– Leaves thin, vascular bundles in one line, less numerous (<30), largest with diameter> ¾ the thickness of the leaf blade ................................................................................................................. 2

2. Vascular bundles <15, midrib prominent or not, largest bundles in position 2 or 3(–4–5) .............. 3 – Vascular bundles> 22, midrib prominent, largest bundle in position 5(–6) ..................................... 4

3. Supernumerary fibre bundles numerous on both sides (> 35), large ( Fig. 4A ), largest vascular bundle in position 2, midrib prominent in leaf section ............................................. D. unicarinatum Kores

– Supernumerary fibre bundles only on abaxial side, few (<15), small, largest vascular bundle in position 3(–4–5), midrib not prominent in leaf section ....................................................................... ......................................................................................... D. butinii M.Pignal & Munzinger sp. nov.

4. Margins obtuse in transverse section ( Fig. 4 Ba) ................................................................................. .............................................................................. D. letocartiorum Munzinger & M.Pignal sp. nov. – Margins truncate in transverse section ( Fig. 4 Bb) .................................... D. camaridiorum Rchb. f.

Figures

Fig. 4. Drawing of transverse sections of leaves of three graminoid species of Dendrobium. A. Total section of D. unicarinatum Kores (H.S. MacKee 44925).Vascular bundles arerepresented by empty circles and are numbered starting from the lamina margin, black spots indicate fibre bundles. B. Leaf margins sections, a. D. letocartiorum Munzinger & M.Pignal sp. nov. (H.S. MacKee 37760); b. D. camaridiorum Rchb.f. (H.S. MacKee 24639). Scale bar = 1 mm.