Abstract Detail

Development and Structure

Matel, Theodore [1], Gandolfo, Alejandra [2].

Leaf epidermal micromorphology of South American Anacardiaceae.

Anacardiaceae, the cashew family, comprise around 80 genera and 600 species and include trees, shrubs and lianas. They are well-known for their crop (cashew, pistachio, mango, pink peppercorn) and dermatitis causing species (poison sumac, poison ivy) and occur in tropical wet, tropical dry, and temperate regions throughout the world. The Anacardiaceae have a convoluted taxonomic history, but at least two subfamilies—Anacardioideae and Spondioideae— have been consistently distinguished by the number of locules per ovary, single and 2-5 respectively. Molecular phylogenetic studies from ETS, trnL, trnL-F, and rps16 sequence data corroborate a two-subfamily classification system. Additionally, it was suggested that trichome morphology characterizes the two subfamilial clades, with the Spondioideae united by multicellular stalked trichomes and the Anacardioideae by unicellular stalked trichomes. In a cladistic analysis of Pseudosmodingium and some closely related genera, it was also found trichomes to be a useful morphological character in delineating individual genera. Despite its significance as a taxonomic character for the intrafamilial classification of the family, trichome morphology has been systematically studied for few groups of related genera or species in the Anacardiaceae. At present, published studies have been limited to the five North American species of Rhus subgenus Rhus, and select species from the genera Bonetiella, Cardenasiodendron, Cotinus, Pseudosmodingium, Spondias, and Toxicodendron. A more comprehensive study of leaf epidermal characters at the generic level will improve our understanding of the relationships between taxa, both living and fossil, within the family. Fossil leaves of Anacardiaceae are reportedly abundant and widespread in the Miocene to Eocene fossil floras of Central and South America; while unconfirmed records of fossil leaves with putative affinity to extant genera Astronium, Schinopsis, and Schinus have been reported from the Eocene Rio Pichileufu paleoflora.The goal of our study is to describe micromorphological characters of the leaf epidermis in various South and Central American genera of Anacardiaceae using scanning electron and light microscopy and to place these characters in a phylogenetic context. The focal point of the study is a putative natural group (Anacardioideae 2) which comprises the genera Amphipterygium, Apterokarpus, Astronium, Cardenasiodendron, Euroschinus, Lithraea, Loxopterygium, Mauria, Myracrudon, Ochoterenea, Orthopterygium, Schinus, Schinopsis, and Thyrsodium. Preliminary observations indicate that multicellular glandular hairs and filiform, unicellular hairs with an ornamented surface are common on the abaxial surface of the leaf. Most genera are hypostomous with paracytic stomata. Although some species of Schinus and Schinopsis are amphistomous, and stomata are commonly anomocytic in Schinus.

1 - Cornell University, Plant Biology, 406 Mann Library, Ithaca, NY, 14850, United States
2 - Cornell University, Plant Biology Section, 512 Mann Library , Ithaca, New York, 14853, United States

Keywords:
Anacardiaceae
trichomes
Stomata
South America
Rio Pichileufu
Schinus
Glandular Hairs.

Presentation Type: Oral Paper
Number: DS2004
Abstract ID:485
Candidate for Awards:Maynard F. Moseley Award,Developmental and Structural Section Undergraduate Student Registration Award