The new genus, Morenoa fertilis from the early Cretaceous beds of the Baqueró Formation (Santa Cruz Province, Argentina) is here described. This conifer is referred to the family Podocarpaceae on account of its vegetative as well as reproductive male organs that include bisaccate pollen grains. The ultrastructure of the leaf cuticle (of the Elatocldus type) and the pollen grains (of the Podocarpidites type) was studied with transmission electron microscopy. Comparision with fossil and extant taxa of the family are also made, including the other three fossil genera known in fertile state from the same formation. The excellent preservation of the closed pollen sacs permitted the recognition of still inmature tetrads and a high inner content of Ubisch bodies. Epiphyllous fungi were also recognized on the leaf epidermis suggesting a mild and humid climatic regime.Some degradation of the leaf cuticles was observed, possibly related in part to fungal activity.
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"The studies on the fossil leaf cuticular ultrastructure using transmission electron microscopy started with the pioneer work of Archangelsky et al. (1986). Since then, the leaf cuticular ultrastructure is known for a number of fossil taxa or groups, including pteridosperms (Taylor et al., 1989; Baldoni and Barale, 1996; Labe and Barale, 1996; Maheshwari and Bajpai, 1996; Bajpai, 1997; Guignard et al., 2001), bennettitaleans (Barale and Baldoni, 1993; Villar de Seoane, 2001), cycadaleans (Artabe and Archangelsky, 1992; Villar de Seoane , 1997b), ginkgoaleans (Taylor et al., 1989; Villar de Seoane , 1997a; Guignard and Zhou, in press), czekanowskialeans (Zhou and Guignard, 1998), as well as conifers (Archangelsky and Taylor, 1986; Archangelsky et al., 1986; Del Fueyo et al., 1990; Barale et al., 1992; Guignard et al., 1998; Villar de Seoane, 1998; Zhou et al., 2000). Most of the cuticle is marked [Vol. "
[Show abstract][Hide abstract] ABSTRACT: Sphenobaiera huangii (Sze) Hsü is typical Early Mesozoic fossil foliage of Ginkgoales in China. It has been recorded from the Upper Triassic to the Lower Jurassic. The cuticular anatomy is investigated based on material from the type locality, Lower Jurassic Hsiangchi Formation, Zigui County, Hubei Province. The specimens are similar to S. huangii, but contain new information about leaf morphology and cuticular anatomy. Lower and upper cuticle is investigated using light and electron microscopy (LM, SEM, and TEM). Many features are described for the first time, including general structures of lower and upper cuticle, stomata, papillae, and cuticular ultrastructure. At the ultrastructural level, two layers have been distinguished in both lower and upper cuticle, including a homogeneous outer layer with granules and a heterogeneous inner layer with fibrils. Based on a literature comparison between S. huangii and other relevant species of Sphenobaiera, S. huangii may represent the best-known taxon in the genus Sphenobaiera in both leaf morphology and cuticular structures. This study provides the first detailed ultrastructural data on the leaf cuticle of Sphenobaiera, one of the oldest foliage taxa of Ginkgoales, and offers further evidence for potential discussion on the taxonomic relationships of S. huangii with other ginkgoalean taxa.
American Journal of Botany 04/2005; 92(4):709-21. DOI:10.3732/ajb.92.4.709 · 2.60 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Leaf cuticles of Phoenicopsis and Arctobaiera collected from the Middle Jurassic Yima Formation, Henan Province, Central China were studied with transmission electron microscopy. The upper and lower cuticles are generally similar in ultrastructure. The cuticle is usually composed of two parts. The upper part is finely granular. The lower part is mainly fibrillar. In the upper cuticle there is normally a thin basal granular layer. The structure appears to be close to Type 3 of Holloway, but it has an inner granular layer and the fibrillae are usually more parallel in orientation. This type of cuticle is also different from those of the other fossil plants. This is the first time the ultrastructure of leaf cuticles of the Czekanowskiales has been studied. It is of interest that the two taxa of the same plant group bear a similar cuticular ultrastructure.
Review of Palaeobotany and Palynology 08/1998; 102(3):179-187. DOI:10.1016/S0034-6667(98)80018-3 · 1.94 Impact Factor