Systematics/Phytogeography / Taxonomie/ Section
Horn, James W. , Fisher, Jack B. , Tomlinson, P. Barry .
The construction and evolution of palm leaves from an anatomical perspective (Arecaceae)Â .
In surveying the vegetative anatomy of palms for the second edition of the 1961 volume “Palmae” for the series Anatomy of Monocotyledons leaf material of all genera has been studied. Observations are based on wet preparations of sections, macerations and lamina scrapes; these are fully supplemented by lamina clearings. The wealth of new structural data obtained, when analyzed in a comparative phylogenetic framework, yields new insight at all hierarchical levels regarding structural diversification of palm leaves. Here we present our major findings at the family level, with emphasis on characters pertaining to the architecture of the lamina. This larger view reveals distinct changes in lamina construction from early- to later-diverging subfamilial clades. Calamoideae and Nypoideae—successively sister to all other palms—have pinnae with longitudinal veins bridged to the adaxial surface layers by a palisade of ad/abaxially elongate sclereids. In contrast, the crown clade of Coryphoideae, Ceroxyloideae, and Arecoideae possess the derived character state of vein bridging (when present) by proximodistally elongate fibers. Other lamina characters that show fundamental differences within palms include: the type and distribution of expansion tissue, architecture and sheathing of transverse commissures, construction of the surface layers (epidermis and hypodermis) and midrib constriction. The synthesis of these results will be emphasized and discussed.
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Fairchild Guide to Palms
1 - Fairchild Tropical Botanic Garden, Center for Tropical Plant Conservation, 11935 Old Cutler Road, Coral Gables, Miami, Florida, 33156-4242, USA
2 - Fairchild Tropical Botanic Garden, Center for Tropical Plant Conservation, 11935 Old Cutler Rd., Coral Gables, FL, 33156-4242
3 - National Tropical Botanical Garden, The Kampong, Coconut Grove, Florida, 33133, USA
Presentation Type: Oral Paper:Papers for Sections
Date: Tuesday, July 29th, 2008
Time: 8:15 AM