Vladimariales ordo nov. (Gymnospermae) from the Middle Jurassic deposits of the Mikhailovskii rudnik locality (Kursk Region,European Russia)

Composite seed-bearing capsules (formed by fusion of eight radially arranged elementary capsules), assigned to a new monotypic order Vladimariales ordo nov., were found in the Upper Bathonian deposits of the Mikhailovskii rudnik locality (Zheleznogorsk town, Kursk Region). In its morphology, the new order demonstrates valuable, phylogenetically conditioned similarity to Peltaspermales and Umkomasiales, but it is evolutionarily more advanced than these latter. A base of the composite capsule is supported by a collar on a stalk, which in external appearance is not different from collar of Ginkgo L., but has stalk, vascularized in a different way (its conducting tissue consisted of eight radially arranged collateral vascular bundles; each vascular bundle correspond to one of eight fused elementary capsules, each of which contain a solitary seed). Capsules and seeds are inverted relative to the collar; as a result, collar protects micropilar tips of seeds. The presence of collar and whole aspect of the new plant composite capsules give them the significant superficial similarity with seed-bearing organs of modern Ginkgo. Mature composite capsule in Vladimariales ordo nov. dehisced along the lines of fusion of elementary capsules, forming the composite capsule, and scattered seeds; opened composite capsule detached from axis. The significance of the new order for gymnosperm phylogeny is discussed.     

Aspects of permian palaeobotany and palynology,VII. the majonicaceae,a new family of late permian conifers

On the basis of rich vegetative and fertile material from the Val Gardena Formation in the Dolomites and the Vicentinian Alps, coniferous remains have been studied in detail with the aid of cuticle analysis. Except the genus Ortiseia Florin, three other natural genera can be distinguished: Majonica nov. gen, Dolomitia nov. gen. and Pseudovoltzia Florin. Within both Majonica and Dolomitia a single species is recognized, Majonica alpina nov. sp. and Dolomitia cittertiae nov. sp., respectively. Within Pseudovoltzia two species can be recognized: P. liebeana (Geinitz) Florin and P. sjerpii nov. sp.The genera Majonica, Dolomitia and Pseudovoltzia are associated with ovuliferous fructifications and Majonica even with polliniferous cones and bisaccoid bitaeniate pollen grains.A new family—the Majonicaceae—is proposed to include the genera Majonica, Dolomitia and Pseudovoltzia. The family is characterized by a peculiar organization of the ovuliferous dwarf-shoots, i.e. the places of ovule-attachment on the lateral fertile scales varying from explicitly laterally situated to more or less shifted to the adaxial side of the dwarf-shoot.     

A new genus <Emphasis Type="Italic">Navipelta</Emphasis> (Peltaspermales,Pteridospermae) from the Permian/Triassic boundary deposits of the Moscow syneclise

A new genus of peltaspermalean ovuliferous organs Navipelta gen. nov. is described from the terrestrial deposits of the Nedubrovo locality (village of Nedubrovo, Vologda Region, Russia), belonging to the base of Vetlugian Group (Upper Permian-Lower Triassic). Data on the anatomy of the peltate bilateral ovuliferous organs are obtained for the first time. Vascular strands in the peltoid depart from that of a stalk and branch up to three times distally. Transfusion tissue around the vascular strands is well developed. The new genus had a system of radially arranged resin canals, broaden into large secretory cavities.     

MORPHOLOGICAL STUDIES OF THE NYMPHAEACEAE SENSU LATO. XVII. FLORAL ANATOMY OF ONDINEA PURPUREA SUBSPECIES PURPUREA (NYMPHAEACEAE)

Classification and phylogeny of the Nymphaeaceae are unresolved. This study provides floral anatomical data that will assist in elucidating generic interrelationships and systematic relationships to other taxa of angiosperms. The floral anatomy of Ondinea purpurea den Hartog subsp. purpurea has been examined utilizing light microscopy. The peduncle possesses stelar vascular bundle complexes and cortical vascular bundles. Cortical bundles terminate within the peduncle. Each bundle complex consists of 2 collateral bundles on the same radius, the inner bundle inverted; 2 protoxylary lacunae occur yet differ in structure and function. Progressing acropetally, the inner xylary lacunae become discrete mesarch strands surrounded centrifugally by a vascular cylinder formed by divisions and anastomosing of the bundle complexes. Together these become the massive receptacular vascular plexus. The plexus provides collateral traces to the floral organs. Each sepal receives 3 traces that separate from the plexus as 1–3 lateral traces. Petals are absent and no vestigial petal traces have been observed. Distally, the plexus forms several large strands of connate gynoecial and androecial traces termed the principal vascular bundles (PVBs). Ventral veins separate from the PVBs and the latter extend acropetally through the outer ovary wall. Branches of the ventrals and PVBs contribute to septal vascular reticula from which each ovule is supplied by one vascular bundle. Each stamen receives 1 trace from branches of the PVBs. The ventrals and PVBs terminate within the carpellary lobes. A comparative anatomical study is offered that supports the inclusion of Ondinea in the Nymphaeaceae sensu stricto.     

铁筷子(毛茛科)营养器官的结构及其系统学意义

应用解剖学方法,对铁筷子(Helleborus thibetanusFranch.)(毛茛科)营养器官的结构进行了研究。结果表明,铁筷子根的初生结构观察到三原型、四原型和六原型。营养器官中的维管束在横切面上木质部中的导管分子不呈“V”字形排列;根状茎的次生结构由外向内为表皮、皮层和维管柱,髓射线发达。茎的初生结构中多个维管束排列成环状,维管束鞘分化不明显,节部为单隙三迹,叶迹分别来自于3条维管束或同一条维管束。叶为两面叶,表皮细胞不规则;气孔器只分布于下表皮,为毛茛科典型的无规则型气孔。从铁筷子营养器官的解剖学特点来看,与毛茛科其它植物基本相同,但在营养器官中维管束木质部不呈“V”字形、维管束鞘分化不明显、节部具单叶隙等特征上与其它毛茛科植物不同。     

A NEW SCIADOPITYACEOUS SEED CONE FROM THE UPPER CRETACEOUS OF HOKKAIDO,JAPAN

A sciadopityaceous seed cone, Sciadopityostrobus kerae, gen. et sp. nov., is described on the basis of a permineralized specimen from the Upper Cretaceous (Cenomanian–Coniacian) of Hokkaido, Japan. The peel method was applied for anatomical observations. The seed cone consists of a cone axis receiving numerous cone scale complexes that are arranged helically. Each complex generally has five inverted ovules that are oriented adaxially. The cone is similar to those of living Sciadopitys verticillata with respect to its peltate cone scale complex, with free apices of both bract and ovuliferous scale, trichomes on the bract, and a trifurcated ovuliferous scale strand. In the fossil, the bract and ovuliferous scale strands fuse with each other in the basal part of the cone scale complex, while S. verticillata bract and ovuliferous scale strands are derived separately from the vascular cylinder and remain separate throughout their length. The present specimen is one of the oldest records of structurally preserved cones that can be assigned to the family Sciadopityaceae.     

Novel double wing morphology revealed in a South African ovuliferous glossopterid fructification: Bifariala intermittens (Plumstead 1958) comb. nov.

Plumstead (1958) established Hirsutum intermittens for glossopterid fructifications with a putative bi-sporangiate, bi-valved architecture but later workers reinterpreted the fossils predominantly as ovuliferous, dorsiventrally flattened, bilaterally symmetrical organs, with a central seed-bearing receptacle and a single finely striate peripheral wing. The wing morphology is central to both the generic and specific diagnoses. New analysis of many South African impressions reveals the presence of two superposed wings flanking the flattened receptacle of H. intermittens. One wing is radially fluted and striated with rounded basal lobes, whereas the other has distinctive distally arched striations and an extended apex. The double-winged structure is unlike that of other glossopterid fertile organs and probably accounts for Plumstead's misinterpretation of the fructification as bivalvate. The specimens are assigned to Bifariala intermittens (Plumstead, 1958) comb. nov., emend. Prevec because Hirsutum is unacceptable according to ICBN rules. Revelation of novel architectural details highlights the value of impression fossils for resolving the gross structure of gymnosperm fertile organs. The newly defined second wing provides an additional character to be considered in the search for homologies of the ovule outer integument or cupules in derived seed-plants.     

VEGETATIVE AND FERTILE STRUCTURES OF CYATHOTHECA VENTILARIA FROM THE UPPER PENNSYLVANIAN OF THE APPALACHIAN BASIN

Permineralized stems, leaves and a fertile structure assignable to Cyathotheca Taylor are described from the Late Pennsylvanian Duquesne Coal of eastern Ohio. The new material, C. ventilaria sp. nov., provides the first evidence of vegetative structures for the genus. Vegetative parts are referred to the fertile fragments based upon distinctive vascular morphology, common histological features, and close association. Stems are up to 5.0 mm in diam and have an apparently endarch dictyostele with scalariform metaxylem tracheids. Secondary xylem consists of tracheids with bordered pitting and uniseriate, parenchymatous rays 1–9 cells high. Leaves are arranged in a 3/8 pattern. They are small, pinnately-lobed, and vascularized by an U-shaped bundle. Distal to divergence, one of the apparent leaf traces becomes radial to resemble the base of a fertile structure. This implies a mode of attachment for the fructification and suggests evidence to interpret its homologies. The fertile specimen consists of laminae that diverge from a short stalk, and bifurcate distally. Laminae bear sporangia 0.6–0.7 mm in diam attached adaxially by vascularized pedicels. Spores average 36 μm in diam and are of the Kewaneesporites type. The combination of features now known for Cyathotheca exclude it from assignment to a currently-recognized major group of vascular plants, thus emphasizing that the Pennsylvanian coal swamp flora included a greater diversity than commonly is interpreted.     

Yezonia,a new section ofAraucaria (Araucariaceae) based on permineralized vegetative and reproductive organs ofA. vulgaris comb. nov. from the upper cretaceous of Hokkaido,Japan

A new specimen of an araucarian cone,Araucaria nihongii, was found attached to the vegetative organs ofYezonia vulgaris, and is described asAraucaria vulgaris comb. nov. Thick branches show characteristic bark structure with lenticular patches. Secondary wood is usually araucarioid. Leaves are arranged helically on shoots, which are imbricate, appressed and fused to surface of the stem. External and anatomical features of leaves closely resembleBrachyphyllum. The seed cone is spherical with winged bracts and thin ovuliferous scales. One seed is borne per cone-scale complex. The seed coat and nucellus wall show typical araucarian structure. An araucarian plant that boreBrachyphyllum-like foliage and aEutacta-like seed cone was predicted by Harris in 1979. This reconstructed plant,Araucaria vulgaris, supports this theory and proves the presence of an extinct characteristic-form of the genus. A new section of the genus was proposed forAraucaria vulgaris. Structure and Affinities of the Petrified Plants from the Cretaceous of Northern Japan and Saghalien XV, Consecutive number from previous paper (Nishidaet al. 1993).     

A new Late Cretaceous ginkgoalean reproductive structure Nehvizdyella gen. nov. from the Czech Republic and its whole-plant reconstruction

During the Mesozoic Era, gingkoaleans comprised a diverse and widespread group. Here we describe ginkgoalean fossils in their facies context from the Late Cretaceous (Cenomanian) Peruc-Korycany Formation of the Czech Republic and present a reconstruction of tree architecture and ecology. Newly described in this study is the ovuliferous reproductive structure, Nehvizdyella bipartita gen. et sp. nov. (Ginkgoales). This ovuliferous organ consists of a bifurcating axis, terminated by large cupule-like structures, probably homologous to the collar of the recent Ginkgo. Each cupule encloses an orthotropous ovule. In specimens with the early developmental stages preserved, the entire ovule and young seed, with the exception of the micropylar area, is embedded in the cupule. Mature seeds consist of sclerotesta and sarcotesta. Monosulcate pollen grains of Cycadopites-type are found adhering to the seeds. Although similar to Ginkgo in terms of its large size and reduced number of seeds, N. bipartita differs from the extant genus in having ovules completely enclosed in a cupule-like structure. The co-occurrence of N. bipartita with ginkgoalean leaves of Eretmophyllum obtusum (Velenovsky) Kva?ek, J., ginkgoalean short shoots of Pecinovicladus kvacekii Falcon-Lang, and ginkgoalean trunk wood of Ginkgoxylon gruettii Pons and Vozenin-Serra in monodominant taphocoenoses at four geographically distant localities suggests that these remains all belong to one plant. This is supported by the close morphological and anatomical similarity between the different organs. Facies analysis of plant assemblages indicates that our Cretaceous tree occupied a water-stressed coastal salt marsh environment. It therefore represents the first unequivocal halophyte among the Ginkgoales.     

A New Morphological Interpretation of the Female Reproductive Organs in Ginkgo biloba L., with a Phylogenetic Consideration on Gymnosperms

The ovuliferous structure of Ginkgo biloba L. has been variously interpreted morphologically. As a result the systematic position and the relationship with other gymnosperms of this ancestral gymnosperm have long been under dispute. In the present paper, a brief survey of the main views as to the nature of the ovuliferous structure is givcn. Based on morphological and teratological data previously reported, a new interpretation is proposed. The essential points are summarized as follows: 1. In morphological essence, a fertile dwarf shoot with some ovuliferous structures in Ginkgo biloba L. might as a whole be nothing but a megasporophyll strobilus (female cone), which is shared actually by all the conifers in the gymnosperms. The fertile dwarf shoot has appearance extremely similar to that of the vegetative dwarf shoot, suggesting that in Ginkgo biloba L. the vegetative organs and the reproductive organs have not been yet well differentiated, and thus its megasporophyll strobilus might represent one of the most primitive compound strobilus types. 2. In Ginkgo biloba, the ovuliferous structure borne in the axil of a scale leaf (sometimes a normal leaf) on the dwarf shoot, together with the scale leaf itself, might be the homogenous organ corresponding to the bract-scale and seed-scale complex of the compound female strobilus of the typical conifers. The complex is a relatively isolated reproductive unit on the strobilus. The normal leaves and the scale leaves on the dwarf shoot might be equivalent to the bract-scales in the typical cones, though the normal leaves still retain the vegetative nature as the foliage leaves on the vegetative shoot. The stalk hearing ovules at its top might be equivalent to a seed-scale of the typical cones. 3. The megasporophyll strobilus in Ginkgo biloba, namely a whole fertile dwarf shoot as mentioned above, seems to show much more primitive characteristics than those of typical conifers. In this plant it is very difficult to distinguish the fertile dwarf shoot from the common vegetative dwarf shoot before reproduction time. Moreover, its megasporophyll strobilus often exhibits more atavistic abnormalities than those of other conifers. All the evidence indicates that the primitive ancestor of conifers might have had the fertile organs which might be of basically identical morphology as vegetative shoots, except that in the fertile organs there might exist numerous fertile leaves bearing one or many ovules. 4. The longer stalk of the ovuliferous structure in Ginkgo biloba might have come from mainly a secondary elongation growth of the seed scale, and only a little part of it might be the remains of the original shoot. The fork structure bearing ovules at the top of the stalk might be the rudementary part of the petioles of the only two extremely reduced megasporophylls. The collar around the base of the ovule might be a secondary protective structure. 5. A correct morphological interpretation of the female strobilus in Ginkgo biloba is doubtless of important significance for our better understanding of the evolution of the female reproductive organs in conifers. According to our interpretation mentioned above, together with the concept of the bractscale and seed-scale complex proposed in the present paper, which is mainly based on the concept of the seed-scale complex propose by Florin, here we put forward an evolutionary theory of the bract-scale and seed-scale complex. According to this theory, the female reproductive organs of the ancestral conifers should be very similar, as mentioned above, to the sterile foliage shoot except that the former might have some fertile leaves which could produce ovules at reproduction time. This ancestral female reproductive organ type might have had evolved towards two directions and thus formed two main evolutionary lines. One is represented by the genus Cycas and we may call it the Cycas Evolutionary Line (C-line), in which the megasporophyll strobilus is monopodial, with the fertile leaves and sterile bracts occurring directly on the main axis. The Cycadaceae is the only living gymnosperm member along this evolutionary line. The second line is represented by all the conifers including Ginkgo, which all have the structure of the bract-scale and seed-scale complex, and thus we called it the "Bract-scale and Seed-scale Complex Evolutionary Line" (BS-line). The members along this line have multipodial female strobilus, i.e. compound strobilus. On the main axis occur some sterile vegetative bracts. In the axils of some or most of the bracts occur the seed-scales. The seed-scales are actually the remains of the extremely, or smetimes completely reduced fertile shoots. Each part of the bractt-scale and seed-scale complex and the main axis of the strobilus could have undergone independent or correlated changes, and thus have had formed various types of strobilus which are found in the living conifers. 6. Our theory on the evolution of the bract-scale and seed-scale complex seems to support the division of all the gymnosperms into two major groups as proposed by Chamberlain, and is also in favour of the placement of Ginkgo biloba into the conifers as the most primitive member along BS-line. 7. Based on their similar morphological characters, it can be considered that Ginkgo biloba might have close relationships with the Nageiaceae, Ephedraceae, Welwitschiaceae and Araucariaceae. All these groups have multinerved leaves without costa. These living gymnosperms might have a more direct relationship withthe ancestral cordaites.     

六盘山鸡爪大黄蒽醌类化合物积累特征的研究

采用多种组织化学方法研究了六盘山鸡爪大黄营养器官中蒽醌类化合物的积累特征.结果显示:蒽醌类化合物在根中分布于周皮的木栓层和栓内层、次生维管组织的维管射线和根中央的部分木薄壁细胞内,且维管射线是根中贮藏和积累蒽醌类化合物的主要组织;在根茎中分布于周皮的木栓层和栓内层、次生维管组织的形成层和维管射线,以及髓的异常维管束射线中,且维管射线是根茎中贮藏和积累蒽醌类化合物的主要组织;在茎中主要分布于表皮、近表皮皮层和维管束的维管束鞘及其薄壁细胞,大型和小型维管束之间和周围的部分薄壁细胞,以及髓射线中有不同程度的分布;在叶中主要积累在叶柄的表皮、叶柄和大叶脉的部分基本组织、维管束的部分薄壁细胞等部位.结果表明,六盘山鸡爪大黄的根和根茎是蒽醌类化合物贮藏和积累的主要器官,维管射线是其贮藏和积累的主要组织,而且各营养器官中蒽醌类化合物积累的数量与植物各相关器官组织的发育程度、细胞中含淀粉粒的多少存在着一定的相关性.     

AGAMOUS subfamily MADS-box genes and the evolution of seed cone morphology in Cupressaceae and Taxodiaceae

In this comparative developmental genetics study, we test hypotheses based on fossil and morphological data on reproductive organ morphology and evolution in conifers--specifically, the ovule-bearing organ in Cupressaceae and Taxodiaceae. Genes homologous to the Arabidopsis gene AGAMOUS are expressed in ovuliferous scales of spruces (Picea) throughout development. Previous studies have shown that the AGAMOUS subfamily of MADS-box genes predates the split between angiosperms and gymnosperms, and that these genes have in part conserved functions in reproductive development among seed plants, especially in the specification of identity of the ovule-bearing organs. These data indicate that their expression in conifer families other than Pinaceae might be used as markers for organs homologous to the Pinaceae ovuliferous scale. Here we have isolated putative AGAMOUS orthologs from Cupressaceae and Taxodiaceae and analyzed their expression pattern in seed cones to test for the presence of morphological homologs of ovuliferous scales. Our results were not congruent with the hypothesis that the tooth of the Cryptomeria seed cone is homologous to the Picea ovuliferous scale. Likewise, the hypothesis that the bracts of Thujopsis and Juniperus contain fused ovuliferous scales was not supported. However, we found expression of AGAMOUS homologs in the sterile bracts of Cupressaceae seed cones at late developmental stages. This expression probably represents a novel gene function in these conifer families, since no corresponding expression has been identified in Pinaceae. Our study suggests that the evolutionary history of modern conifer cones is more diverse than previously thought.     

Zhutheca Liu, Li et Hilton gen. nov., the fertile pinnules of Fascipteris densata Gu et Zhi and their significance in marattialean evolution

The morphology of the fertile pinnules of Fascipteris densata Gu et Zhi have been subjected to a detailed morphological investigation based on recently collected specimens from the Upper Permian of Yunnan Province, south China. These investigations have revealed that this species possesses synangia of the Asterotheca-type, situated in two or three rows either side of the midrib on a Fascipteris-type pinnule. This arrangement of Asterotheca-type synangia is extremely unusual considering that all other reports of this genus are with a single row of synangia located on each side of the midrib of a pecopteroid-type pinnule. As a consequence of this unique morphological arrangement, a new genus, Zhutheca densata Liu, Li et Hilton gen. et comb. nov. has been created to distinguish this material from other specimens of the Asterotheca and Fascipteris types. The structure and arrangement of the fertile pinnule of Zhutheca are compared with other Palaeozoic and Mesozoic marattialean taxa with which it shares certain features of its morphology. In addition, the stratigraphic, evolutionary and phylogenetic significance of Zhutheca are considered in detail.     

A taxodiaceous seed cone from the Triassic of Antarctica

A silicified seed cone is described from the lower Middle Triassic of A silicified seed cone is described from the lower Middle Triassic of Antarctica. The cone measures up to 3.4 cm long and 1.4 cm wide, and consists of helically arranged cone scales attached to a eustelic axis. Bract and ovuliferous scale are approximately of equal length and fused at the base. The bract is entire and vascularized by a single trace. The ovuliferous scale contains five distal lobes, each vascularized by a terete strand that divides to form a smaller trace to each of the five inverted ovules. Ovules are small and flattened with the three-parted integument attenuated into oppositely positioned lateral wings. The Triassic specimens are compared with both extant and fossil conifer seed cones and believed to have their closest affinities within the Taxodiaceae.     

THE ORGANIZATION OF THE VASCULAR SYSTEM IN THE STEMS OF THE NYMPHAEACEAE. II. NYMPHAEA SUBGENERA ANECPHYA,LOTOS, AND BRACHYCERAS

The anatomy and organization of the stem vascular system was analyzed in representative taxa of Nymphaea (subgenera Anecphya, Lotos, and Brachyceras). The stem vascular system consists of a series of concentric axial stem bundles from which traces to lateral organs depart. At the node each leaf is supplied with a median and two lateral leaf traces. At the same level a root trace supplies vascular tissue to adventitious roots borne on the leaf base. Flowers and vegetative buds occupy leaf sites in the genetic spiral and in the parastichies seen on the stem exterior. Certain leaves have flowers related to them spatially and by vascular association. Flowers (and similarly vegetative buds) are vascularized by a peduncle trace that arises from a peduncle fusion bundle located in the pith. The peduncle fusion bundle is formed by the fusion of vascular tissue derived from axial stem bundles that supply traces to certain leaves. The organization of the vascular system in the investigated taxa of Nymphaea is unique to angiosperms but similar to other subgenera of Nymphaea.     

Frenelopsis alata and its microsporangiate and ovuliferous reproductive structures from the Cenomanian of Bohemia (Czech Republic, Central Europe)

The conifer, Frenelopsis alata (K. Feistmantel) E. Knobloch (Cheirolepidiaceae), occurring mostly in the Cenomanian of Europe, is revised on the basis of the type material. Its comparison with relevant species of Frenelopsis is discussed.The ovuliferous cone associated with the genus Frenelopsis is recorded for the first time. For the associated ovuliferous cones of Frenelopsis, a new genus, Alvinia, is introduced in a new combination for the type: Alvinia bohemica (Velenovsky) comb. n. Its association with Frenelopsis alata is based on the presence of Classopollis pollen adhering to ovuliferous cone scales, and the same type of pollen found in the microsporangiate cone of F. alata, the same cuticle pattern present on ovuliferous cones, sterile twigs and microsporangiate cones of F. alata, and also the co-occurrence of ovuliferous cones or their scales and sterile twigs of F. alata.Large ovuliferous cones of Alvinia bohemica are formed by helically arranged ovuliferous scales subtended by bracts. Each ovuliferous cone scale displays one or two seeds covered by a covering flap, and three appendages, which form distally a funnel-like structure lined in its inner part by long trichomes. Numerous pollen grains of Classopollis adhere to the trichomes, and the structure is considered to function as a protostigmatic area.The ovuliferous cones of Alvinia differ from similar cones of the Cheirolepidiaceae, Hirmeriella and Tomaxellia, mainly in a high state of unification of the ovuliferous cone scale, reduction of appendages and in a presence of the protostigmatic funnel-like structure.The ovuliferous cones, Alvinia bohemica, rarely occur intact, so it is assumed that they disintegrate when mature. It seems likely that they were not woody. This assumption is supported by the flattened appearance of cones and their cone scales in the sediment, their flexibility and the absence of massive coaly matter known from cones of the Taxodiaceae and Cupressaceae. It is proposed that this type of ovuliferous cone scale indicates a specialized type of pollination. In addition, it is suggested that cone scales enclosing seeds play an important role in propagation.     

DEVELOPMENT OF THE EPIPHYLLOUS INFLORESCENCE OF HELWINGIA JAPONICA (HELWINGIACEAE)

The inflorescence of Helwingia japonica (Thunb.) Dietr. is initiated adjacent to the leaf axil on the adaxial side of the base of a leaf primordium during its second plastochron. The inflorescence which develops from the resulting primordium comes to be situated on the midrib of the mature fertile leaf, through the action of a basal, intercalary meristem. In fertile leaves this meristem develops beneath, as well as above, the insertion of the inflorescence primordium on the leaf primordium. The same meristem is present in sterile leaves as well. A separate, adaxial vascular bundle departs from the leaf trace in the base of the petiole and leads to the inflorescence, in the mature fertile leaf. This adaxial vascular bundle is absent in sterile leaves. It is argued that the vascular anatomy does not conclusively confirm the hypothesis that the epiphyllous inflorescence is the congenital fusion product of a leaf and an axillary inflorescence. Instead, it is suggested that the interplay of changes in the position of primordium initiation, and intercalary growth, offers an ontogenetic explanation of the situation, which in turn may be related to the phylogeny of the species in question. It appears to be misguided and futile to look for homologies (i.e., 1:1 correspondences) between fertile and sterile leaves, since 1:1 correspondences do not exist in this case.     

A NEW TAXODIACEOUS SEED CONE FROM THE OLIGOCENE OF WASHINGTON

Cunninghamiostrobus goedertii is described as a new species based on permineralized seed cones from the Early Oligocene of Washington. The fossils come from the Makah Formation and were found on the northern shore of the Olympic Peninsula. The cone consists of numerous bract-scale complexes arranged helically around a central axis. Each bract-scale complex has a large bract bearing a small flap of tissue adaxially that represents the ovuliferous scale. Up to three seeds were produced on each complex. The vascular trace to the bract-scale complex diverges from the vascular cylinder of the cone axis as a concentric strand. This divides in the outer cortex of the axis to form a large collateral bract tract abaxially and a minute scale trace adaxially. The latter continues outward to supply the ovuliferous scale. The bract trace divides, forming many strands outward which occur in a row with transfusion tissue between them. Many resin canals also occur in the bract. The new cone combines features found in modern cones of Athrolaxis, Cunninghamia, and Taiwania but is most similar to Cunninghamiostrobus yubariensis from the Late Cretaceous of Japan.     

CONE AND OVULE DEVELOPMENT IN SCIADOPITYS (TAXODIACEAE-CONIFERALES)

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.