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Abstract Detail


Stevenson, Dennis [1].

Cycad Teratology: Leaves. .

Cycad Teratology: Leaves. Leaf teratologies are uncommon in cycads. These are most often seen in clustering of pinnae along the rachis as in some species of Ceratozamia or dichotomously divided pinnae as in Macrozamia. Then there is the so-called twisted rachis in C. norstogii that is actually the result of pinna pairs initiated in a helix. In contrast to the twisted rachis seen in several species of Macrozamia. Undulate pinnae margins are found intermittently in the pinnae of some Cycas species. Although not strictly a teratism in sense of a misshaped or misplaced organ(s), 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 a lack of manganese. There is variegation in Zamia variegata that based upon the presumption of 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.

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Presentation Type: Oral Paper
Session: PL8, Paleobotany: Patterns & Trends
Location: /
Date: Thursday, July 22nd, 2021
Time: 3:00 PM(EDT)
Number: PL8001
Abstract ID:55
Candidate for Awards:None

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