Gomortega

Abstract: Nucleotide sequence data from the chloroplast rbcL gene and the trnL-trnF intergenic spacer of 58 species in 38 genera were used to infer the phylogenetic affinities of Monimiaceae to other Laurales, and to assess whether the family in the traditional wide sense is monophyletic Besides Monimiaceae, the Laurales comprise Calycanthaceae, Gomortegaceae, Hernandiaceae, and Lauraceae Magnoliaceae and Myristicaceae were used as outgroups Based on recent molecular data, Amborellaceae and Chloranthaceae, which have sometimes been included in the order, do not belong in the Laurales, and indeed trnL-trnF sequences of Amborella (Amborellaceae) and Hedyosmum (Chloranthaceae) were too different to be unambiguously aligned with the remaining sequences Parsimony analyses of the trnL-trnF and trnL-trnF-rbcL data groups the genera into five major clades, Calycanthaceae, Atherospermataceae, Gomortega , Siparunaceae, and a weakly supported Monimiaceae sstr-Lauraceae-Hernandiaceae clade RbcL data alone provide no resolution at the family level Many aspects of traditional intra-familiar classification of Monimiaceae are supported except that the sole perfect-flowered member of the family, the monotypic Sri Lankan Hortonia , is not basal (13 of 15–22 genera sampled) Instead, there are two major clades in Monimiaceae One comprises the functionally dioecious monospecific Peumus from Chile plus the morphologically and functionally dioecious small genera Monimia from the Mascarenes and Palmeria from eastern Australia and New Guinea The other consists of Hortonia and all remaining genera The atherospermatoids are supported in their traditional circumscription (14 species, 7 genera, of which 10 and 6 were sampled) The neotropical genus Siparuna , different from recent classifications that have stressed its isolation, is genetically and morphologically very close to the West African species Glossocalyx longicuspis Both taxa have unisexual flowers of the same general morphology, and both have unitegmic ovules From the current data it seems that monoecy is basal in Siparuna , but more complete sampling of species with a faster evolving genetic marker is needed for a fuller understanding of the evolution of monoecy and dioecy in this genus

Abstract: The sporoderm ultrastructure of some genera in theLauraceae, Hernandiaceae andGomortegaceae (Laurales) was re-investigated. This and a comparison with some Zingiberalean genera (Canna, Heliconia, Strelitzia) leads to a re-interpretation of the peculiar pollen wall structure of the Lauralean families recently described in this journal (Kubitzki 1981). Their pollen is now interpreted as being nearly exine-less: The (sporopollenin-containing) exine consists only of a thin, skin-like, coherent layer ornamented with spines and globules. The (cellulosic) intine is composed of an unstratified inner and a thick, channelled outer layer. The striking similarity of the pollen ultrastructure between theLaurales studied and some members of theZingiberales can be interpreted as an example of convergent evolution in angiosperm pollen walls.

Abstract: Embryological characters of Siparunaceae, which are poorly understood, were studied on the basis of two constituent genera, an African Glossocalyx and a South American Siparuna, to better understand their evolution within Laurales. These two genera have many embryological characteristics in common with the other lauralean families. Noticeably, they share the multi-celled ovule archesporium (uncertain in Glossocalyx) as a synapomorphy with all the other lauralean families except Lauraceae, the anthers dehisced by valves as a synspomorphy with all the other lauralean families except Calycanthaceae and Monimiaceae, and the bisporangiate anther as a synapomorphy with Gomortegaceae and Atherospermataceae. Siparunaceae are, however, distinct from all other laularean families in having unitegmic ovules that were derived from bitegmic ovules, probably due to an elimination of the outer integument. Likewise, the lack of the testa (i.e., developed outer integument), the "endotegmic" seed coat, and the perichalazal seed at maturity are also characteristics of Siparunaceae. Within the family, Siparuna differs from Glossocalyx in having plural tetrads of megaspores and plural, starchy-rich, one-nucleate, tubular embryo sacs (autapomorphies). On the other hand, Glossocalyx is characterized by having bilaterally flattened seeds (autapomorphy). Although functional aspects of those autapomorphies are uncertain, both Glossocalyx and Siparuna show evolution in different embryological characters.

Abstract: PREMISE OF THE STUDY The floral history of early angiosperms is far from complete. The fossil discussed here has the potential to expand our knowledge of timing, reproductive biology, and paleobiogeography in early angiosperms. METHODS Cutting-edge methodologies in CT scanning in conjunction with tomography software have opened new possibilities for discovering details in amber-preserved fossils that were inaccessible for meaningful study in the past. KEY RESULTS The fossil is small and complex, cupulate, with numerous stamens and a suite of characters distributed in the modern families of Laurales. The most parsimonious placement of the fossil based on morphology is as a sister taxon of Atherospermataceae + Gomortega (Gomortegaceae). CONCLUSIONS This fossil taxon, a Laurasian Lauralean from the mid-Cretaceous, is an important example of fossil Laurales with implications for biogeography and timing in the radiation and extinction in this group.