Abstract Detail

Paleobotany

Cycad Teratology.

Teratisms are often viewed as glimpses of the future; conversely, glimpses of the past; or simply, as failed experiments. Regardless, they are interesting objects of study. In cycads, the most common teratologies are fasciated vegetative shoots and pollen strobili, dichotomously branched strobili, and ovulate strobili developing a vegetative terminal shoot. Less common is the occurrence of more that two ovules on a sporophyll in ovulate strobili and ovules protruding from between peltate megasporophylls with the micropyle external. Although not strictly a teratism in sense of a misshaped organ, chimeras that result in variegation do result in mutations that effect organ appearance and function. In cycads, leaf variegation is rare but when occurring they are usually white or more commonly yellow. Because there is no tunica, there can be no periclinal chimeras. Cycad chimeras are either mericlinal or sectorial. Most are the latter. However those where variegation is limited to leaflet tips are probably mericlinal. There is variegation in Zamia variegata that based upon the presence of a virus. In Cycas seemanii the leaves are entirely yellow when emergent and young and remain that way as they mature and only become green when shaded by new emergent flushes as those mature.

Related Links:
Cycad Pages
World List of Cycads

1 - New York Botanical Garden, 2900 Southern Blvd, Bronx, NY, 10458, United States

Keywords:
cycads
teratism
fasciation
chimera.

Presentation Type: Oral Paper
Session: PAL5, Paleobotany III: Patterns and trends
Location: Virtual/Virtual
Date: Tuesday, July 28th, 2020
Time: 3:00 PM
Number: PAL5001
Abstract ID:115
Candidate for Awards:None