The Experts below are selected from a list of 1407 Experts worldwide ranked by ideXlab platform
P B Tomlinson - One of the best experts on this subject based on the ideXlab platform.
-
seed cone and ovule ontogeny in metasequoia sequoia and sequoiadendron Taxodiaceae coniferales
Botanical Journal of the Linnean Society, 1992Co-Authors: T. Takaso, P B TomlinsonAbstract:TAKASO, T. & TOMUNSON, P. B., 1992. Seed cone and ovule ontogeny in Metasequoia, Sequoia and Sequoiadendron (Taxodiaceae–Coniferales). Structural features of seed cones, up to the initiation of ovules, are developed in the three genera in the summer and late fall prior to pollination in the following spring, when cones renew their further development. Bracts are initiated in a decussate manner in Metasequoia but spirally in Sequoia and Sequoiadendron. No ovuliferous scale is initiated, at most there is a shallow mound of tissue on the adaxial surface of the bract from which the ovules are developed. Metasequoia produces a single series of up to eight ovules in acropetal (centripetal order), Sequoia and Sequoiadendron produce a double series of six to nine ovules, also in acropetal order, since a second series of ovules appear distal to and alternate with the first series. Common features that unite the genera are the somewhat peltate configuration of the cone scales due to late intercalary expansion, the derivation of the vascular supply to the bract-ovule complex from a single bundle and the usual inversion of the seed during late development, to which can be added developmental features. The absence of tooth-like structures, present in some other Taxodiaceae, is discussed in relation to cone evolution in the family being determined by changes in developmental timing. Emphasis is made on the way in which features of morphogenesis, determine cone organization in the three genera independent of an interpretation that relies solely on hypothetical ancestral forms.
-
Seed cone and ovule ontogeny in Metasequoia, Sequoia and Sequoiadendron (Taxodiaceae–Coniferales)
Botanical Journal of the Linnean Society, 1992Co-Authors: T. Takaso, P B TomlinsonAbstract:TAKASO, T. & TOMUNSON, P. B., 1992. Seed cone and ovule ontogeny in Metasequoia, Sequoia and Sequoiadendron (Taxodiaceae–Coniferales). Structural features of seed cones, up to the initiation of ovules, are developed in the three genera in the summer and late fall prior to pollination in the following spring, when cones renew their further development. Bracts are initiated in a decussate manner in Metasequoia but spirally in Sequoia and Sequoiadendron. No ovuliferous scale is initiated, at most there is a shallow mound of tissue on the adaxial surface of the bract from which the ovules are developed. Metasequoia produces a single series of up to eight ovules in acropetal (centripetal order), Sequoia and Sequoiadendron produce a double series of six to nine ovules, also in acropetal order, since a second series of ovules appear distal to and alternate with the first series. Common features that unite the genera are the somewhat peltate configuration of the cone scales due to late intercalary expansion, the derivation of the vascular supply to the bract-ovule complex from a single bundle and the usual inversion of the seed during late development, to which can be added developmental features. The absence of tooth-like structures, present in some other Taxodiaceae, is discussed in relation to cone evolution in the family being determined by changes in developmental timing. Emphasis is made on the way in which features of morphogenesis, determine cone organization in the three genera independent of an interpretation that relies solely on hypothetical ancestral forms.
-
CONE AND OVULE DEVELOPMENT IN SCIADOPITYS (Taxodiaceae‐CONIFERALES)
American Journal of Botany, 1991Co-Authors: Tokushiro Takaso, P B TomlinsonAbstract:Ontogeny of seed cones of Sciadopitys, with special reference to the ovule-supporting structure, is studied in material collected in Japan and Massachusetts. Cones are initiated as lateral or terminal structures in summer and complete the formation of most organs before winter. Bract development is well advanced before ovule-supporting structures are initiated. Continued cone development involves the formation of a narrow ridge of tissue in the axil of each fertile bract. This ridge develops a series of nine (but up to 12) apical lobes in centrifugal order, each of which is the primordium of a future tooth on the ovuliferous scale. Ovules are initiated as outgrowths of the adaxial surface of each lobe so that there is a one-to-one ratio between lobes and ovules. Intercalary extension of the ovuliferous scale itself (distally) and the common base of the bract and ovuliferous scale (proximally) greatly extends the complex. The ovuliferous scale eventually exceeds the subtending bract and its apex becomes recurved. Bracts each have a single trace, but each ovuliferous scale has a pair of traces that proliferate distally to irrigate ovule and scale lobe. Intercalary growth results in recurvature of the ovule trace. The organization of the cone is directly comparable with certain Permian fossils. Sciadopitys also seems unique within the Taxodiaceae in its centrifugal development of the ovule-supporting complex.
-
cone and ovule development in sciadopitys Taxodiaceae coniferales
American Journal of Botany, 1991Co-Authors: Tokushiro Takaso, P B TomlinsonAbstract:Ontogeny of seed cones of Sciadopitys, with special reference to the ovule-supporting structure, is studied in material collected in Japan and Massachusetts. Cones are initiated as lateral or terminal structures in summer and complete the formation of most organs before winter. Bract development is well advanced before ovule-supporting structures are initiated. Continued cone development involves the formation of a narrow ridge of tissue in the axil of each fertile bract. This ridge develops a series of nine (but up to 12) apical lobes in centrifugal order, each of which is the primordium of a future tooth on the ovuliferous scale. Ovules are initiated as outgrowths of the adaxial surface of each lobe so that there is a one-to-one ratio between lobes and ovules. Intercalary extension of the ovuliferous scale itself (distally) and the common base of the bract and ovuliferous scale (proximally) greatly extends the complex. The ovuliferous scale eventually exceeds the subtending bract and its apex becomes recurved. Bracts each have a single trace, but each ovuliferous scale has a pair of traces that proliferate distally to irrigate ovule and scale lobe. Intercalary growth results in recurvature of the ovule trace. The organization of the cone is directly comparable with certain Permian fossils. Sciadopitys also seems unique within the Taxodiaceae in its centrifugal development of the ovule-supporting complex.
Makoto Nishida - One of the best experts on this subject based on the ideXlab platform.
-
Structure and affinities of the petrified plants from the cretaceous of Northern Japan and Saghalien XIIIYubaristrobus gen. nov., A new Taxodiaceous cone from the upper cretaceous of Hokkaido
Journal of Plant Research, 1993Co-Authors: Takeshi Ohsawa, Harufumi Nishida, Makoto NishidaAbstract:Yubaristrobus is a new genus of the Taxodiaceae based on a permineralized seed cone from the Upper Cretaceous of Hokkaido. The type species, Y. nakajimae sp. nov., is characterized by peltate bract-scale complexes consisting of a completely-fused bract and scale. The bract-scale complexes are spirally arranged as in most taxodiaceous genera. Their vascular arrangement is specialized and unique in the Taxodiaceae and suggests a relationship with the Cupressaceae.
-
Structure and affinities of the petrified plants from the cretaceous of Northern Japan and Saghalien. XII.Obirastrobus gen. nov., petrified pinaceous cones from the Upper Cretaceous of Hokkaido
Journal of Plant Research, 1992Co-Authors: Takeshi A. Ohsawa, Harufumi Nishida, Makoto NishidaAbstract:Yubaristrobus is a new genus of the Taxodiaceae based on a permineralized seed cone from the Upper Cretaceous of Hokkaido. The type species,Y. nakajimae sp. nov., is characterized by peltate bract-scale complexes consisting of a completely-fused bract and scale. The bract-scale complexes are spirally arranged as in most taxodiaceous genera. Their vascular arrangement is specialized and unique in the Taxodiaceae and suggests a relationship with the Cupressaceae.
Peter B. Mcquillan - One of the best experts on this subject based on the ideXlab platform.
-
athrotaxivora tasmanica gen sp nov lepidoptera gelechioidea an unusual moth associated with king william pine athrotaxis selaginoides d don Taxodiaceae in tasmanian montane rainforests
Australian Journal of Entomology, 1998Co-Authors: Peter B. McquillanAbstract:The adult, final-instar larva and pupa of Athrotaxivora tasmanica gen. n. and.sp. n. are described. Although a member of the superfamily Gelechioidea, it does not clearly conform to any of the existing gelechioid families or subfamilies but is here tentatively associated with the Xyloryctinae. Larvae are external feeders on the foliage of the King William pine, Athrotaxis selaginoides, in the cool temperate rainforests of western Tasmania. This is the first record of the coniferous family Taxodiaceae as a foodplant for Gelechioidea in the southern hemisphere.
-
Athrotaxivora tasmanica gen. & sp. nov. (Lepidoptera: Gelechioidea): an unusual moth associated with King William pine (Athrotaxis selaginoides D. Don., Taxodiaceae) in Tasmanian montane rainforests
Australian Journal of Entomology, 1998Co-Authors: Peter B. McquillanAbstract:The adult, final-instar larva and pupa of Athrotaxivora tasmanica gen. n. and.sp. n. are described. Although a member of the superfamily Gelechioidea, it does not clearly conform to any of the existing gelechioid families or subfamilies but is here tentatively associated with the Xyloryctinae. Larvae are external feeders on the foliage of the King William pine, Athrotaxis selaginoides, in the cool temperate rainforests of western Tasmania. This is the first record of the coniferous family Taxodiaceae as a foodplant for Gelechioidea in the southern hemisphere.
Takeshi A. Ohsawa - One of the best experts on this subject based on the ideXlab platform.
-
Anatomy and Relationships of Petrified Seed Cones of the Cupressaceae, Taxodiaceae, and Sciadopityaceae
Journal of Plant Research, 1994Co-Authors: Takeshi A. OhsawaAbstract:Morphological features and the affinities of petrified seed cones of the Taxodiaceae, Cupressaceae, and Sciadopityaceae are reevaluated. TheCunninghamia-like plants are the earliest record of the families.Parataiwania explains the divergence ofTaiwania from aCunninghamia-like ancestral form by loss of ovuliferous scale and sclerenchyma.Sequoia-like allies probably diverged from a Cretaceous transitional plant likeYezosequoia and are most diversified in the Late Cretaceous.Yubaristrobus andArchicupressus suggest monophyly ofTaxodium and its allied genera of the Taxodiaceae and the Cupressaceae. The Cupressaceae may be derived from a taxodiaceous plant with orthotropous seeds, acquiring a reniform arrangement of the vascular bundles of the bract-scale complex, decussate or whorled phyllotaxis, and spherical cones consisting of a small number of bract-scale complexes. The Cretaceous fossils of the Sciadopityaceae suggest the ancient origin of the family.
-
Structure and affinities of the petrified plants from the cretaceous of Northern Japan and Saghalien. XII.Obirastrobus gen. nov., petrified pinaceous cones from the Upper Cretaceous of Hokkaido
Journal of Plant Research, 1992Co-Authors: Takeshi A. Ohsawa, Harufumi Nishida, Makoto NishidaAbstract:Yubaristrobus is a new genus of the Taxodiaceae based on a permineralized seed cone from the Upper Cretaceous of Hokkaido. The type species,Y. nakajimae sp. nov., is characterized by peltate bract-scale complexes consisting of a completely-fused bract and scale. The bract-scale complexes are spirally arranged as in most taxodiaceous genera. Their vascular arrangement is specialized and unique in the Taxodiaceae and suggests a relationship with the Cupressaceae.
P-f Tsai - One of the best experts on this subject based on the ideXlab platform.
-
Study of male sterility in Taiwania cryptomerioides Hayata (Taxodiaceae).
Protoplasma, 2006Co-Authors: S.-h. Chen, N-j Chung, Y.-n. Wang, P-f TsaiAbstract:A study of male sterility over a period of three consecutive years on a conifer species endemic to Taiwan, Taiwania cryptomerioides Hayata (Taxodiaceae), was done for this article. With the aids of fluorescence and electron microscopic observations, the ontogenic processes in the fertile and sterile microsporangia are compared, using samples collected from Chitou Experimental Forest and Yeou-Shoei-Keng Clonal Orchard of the National Taiwan University, Nantou, Taiwan. The development of male strobili occurred from August to the end of March. Microsporogenesis starts with the formation of the archesporium and ends with the maturation of 2-celled pollen grains within the dehiscing microsporangium. Before meiosis, there was no significant difference in ultrastructure between the fertile and sterile microsporangia. Asynchronous pollen development with various tetrad forms may occur in the same microsporangium of either fertile or sterile strobili. However, a callose wall was observable in the fertile dyad and tetrad, but not in the sterile one. After dissolution of the callose wall, the fertile microspores were released into the locule, while some sterile microspores still retained as tetrads or dyads with intertwining of exine walls in the proximal faces. As a result, there was no well developed lamellated endexine and no granulate ectexine or intine in the sterile microspores. Eventually, the intracellular structures in sterile microspores were dramatically collapsed before anthesis. The present study shows that the abortion in pollen development is possibly attributed to the absence of the callose wall. The importance of this structure to the male sterility of T. cryptomerioides is discussed.
