Search

Premise of research. The southern conifer family Podocarpaceae inhabits wet environments and is highly diverse in its vegetative and megasporangiate structures. The Podocarpaceae are today divided into a tropical clade and a prumnopityoid clade. We study the morphology and anatomy of leaves and megasporangiate cones at postpollination and the maturity of two native Patagonian Podocarpaceae, Saxegothaea conspicua (tropical clade) and Lepidothamnus fonkii (prumnopityoid clade). We aim to add to the knowledge of the South American Podocarpaceae and to interpret their unique morphologies to aid in our understanding of the deep and cryptic fossil record of the family and its relationships with other conifer families. Methodology. Specimens of S. conspicua and L. fonkii were collected in natural and cultivated populations of southern Chile and imaged using different macro- and microscopic techniques, including epifluorescence, bright-field, and scanning electron microscopy. Pivotal results. Leaf and megasporangiate cone anatomy and morphology are described in detail for both species. For S. conspicua , we observed a helical to slightly planate leaf arrangement with leaf reorientation, expanded leaves without accessory transfusion tissue, an apparent lack of vascularization of the epimatium (which is bikeeled and does not surround the ovule completely), and nonsaccate pollen germinating on the bract toward the protruding nucellus. For L. fonkii , we observed the absence of leaf hypodermis and resin canals, the presence of a micropylar hook in the ovule and seed integument, bisaccate pollen germinating within the ovule, cone bracts reduced in number and size, and a basal receptacle-like structure. Conclusions. Leaf arrangement in Saxegothaea shows an intermediate condition between the primary helical phyllotaxis common in the family and the secondary planate arrangement seen in most podocarps with expanded leaves. Lepidothamnus fonkii was determined to have a false receptacle (i.e., a receptacle-like structure originated from vegetative basal bracts rather than by sterile ovuliferous complexes). The presence of a false receptacle in L. fonkii is a morphological novelty in Podocarpaceae. [ABSTRACT FROM AUTHOR]

Premise of the Study: Seed cone morphology and anatomy reflect some of the most important changes in the phylogeny and evolutionary biology of conifers. Reexamination of the enigmatic Jurassic seed cone Pararaucaria patagonica reveals previously unknown systematically informative characters that demonstrate affinities with the Cheirolepidiaceae. This paper documents, for the first time, internal anatomy for seed cones of this important extinct Mesozoic conifer family, which may represent the ghost lineage leading to modern Pinaceae., Methods: Morphology and anatomy of cones from the Jurassic La Matilde Formation in Patagonia are described from a combination of polished wafers and thin section preparations. New photographic techniques are employed to reveal histological details of thin sections in which organic cell wall remains are not preserved. Specific terminology for conifer seed cones is proposed to help clarify hypotheses of homology for the various structures of the cones., Key Results: Specimens are demonstrated to have trilobed ovuliferous scale tips along with a seed enclosing pocket of ovuliferous scale tissue. Originally thought to represent a seed wing in P. patagonica, this pocket-forming tissue is comparable to the flap of tissue covering seeds of compressed cheirolepidiaceous cones and is probably the most diagnostic character for seed cones of the family., Conclusions: Pararaucaria patagonica is assigned to Cheirolepidiaceae, documenting anatomical features for seed cones of the family and providing evidence for the antiquity of pinoid conifers leading to the origin of Pinaceae. A list of key morphological and anatomical characters for seed cones of Cheirolepidiaceae is developed to facilitate assignment of a much broader range of fossil remains to the family. This confirms the presence of Cheirolepidiaceae in the Jurassic of the Southern Hemisphere, which was previously suspected from palynological records.