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Abstract Detail

Paleobotany

Martinez, Leandro [1], Stevenson, Dennis [2].

Cycad or Cycadeoid?

Cycad or Cycadeoid? The Cycadales and Cycadeoidales (Bennettitales) co-existed during Mesozoic era. Their fossils are easily distinguished from each other on the basis reproductive characters, particularly in phylogenetic analyses. However, their vegetative organs appear very similar, especially foliar features. Stems can generally be assigned based upon anatomy in that cycads have apomorphic structures not found in Bennies. One caveat here is that one must have sections of the lateral buds of a trunk to show that they are or are not reproductive branches. The assignment of isolated leaves is quite a different situation. For fossils, it is usually characters of the epidermal cell patterns and walls and presumed development of stomata and stomatal complexes. It appears that some features of internal leaf and leaflet anatomy could be diagnostic if present or at least looked for in fragments. Among these characters are: Articulate and Decurrent Leaflets, Midribs from Dichotomies, Callus Region at Leaflet Base, Anticlinal Wall Pegs, Perforated Epidermal Cells, Anastomosing of Vein Dichotomies, etc. The aim of this research is to evaluate some of these foliar characters that traditionally separate cycads from bennies.

1 - Instituto de Botánica Darwinion (ANCEFN - CONICET), Labardén 200, San Isidro, Buenos Aires, , CC22 - B1642HYD, Argentina
2 - New York Botanical Garden, 2900 Southern Blvd, Bronx, NY, 10458, United States

Keywords:
Cycadales
Cycadeoidales
Bennettitiales.

Presentation Type: Oral Paper
Session: PAL2, Paleobotany II: Paleozoic and Mesozoic Paleobotany
Location: Tucson G/Starr Pass
Date: Monday, July 29th, 2019
Time: 4:45 PM
Number: PAL2005
Abstract ID:467
Candidate for Awards:None