INVESTIGADORES
DEL FUEYO Georgina Marisa
artículos
Título:
Permineralized seed fern cupules from the Triassic of Antarctica: Implication for cupule and carpel evolution.
Autor/es:
TAYLOR, T.N., G.M. DEL FUEYO & E. TAYLOR
Revista:
AMERICAN JOURNAL OF BOTANY
Editorial:
Botanical Society of America
Referencias:
Lugar: Saint Louis; Año: 1994 vol. 81 p. 666 - 677
ISSN:
0002-9122
Resumen:
In
this paper we describe the first anatomically preserved Mesozoic seed fern
cupule- Petriellaea. The multiovulate cupules were produced singly at
the end of a short dichotomizing axis. Cupules are bilateral with a dorsal
groove and transverse narrow
ventral opening. The vascular system of the cupule consists of a series of
traces that extend up the dorsal surface of the cupule and down the ventral
face. Ovules are orthotropus, sessile, and borne on the adaxial surface of the
leaflike cupule either singly or in multiple rows. They are up to 1.5 mm long, triangular in
transverse section, and characterized by a multilayered integument. Nucellus
and integument are fused throughout their length, but no pollen chamber is
present. In the chalaza is a small vascular disc of transfusion tracheids that
represents the extent of the ovule vascular system. Ovules are interpreted as
being fossilized at a prepollination stage, although a few possess some
evidence of a cellularized megagametophyte. These permineralized cupules
indicate that in at least one Mesozoic seed fern group, ovule enclosure
resultedfrom
the transverse folding (tip to petiole) of a megasporophyll bearing adaxial
ovules. Cupule morphology and ovule enclosure in other Late Paleozoic and
Mesozoic seed ferns is discussed.