A new genus of male cones of voltzialean affinity,Uralostrobus voltzioides nov. gen., nov. sp., from the Lower Permian of the Urals (Russia)

A new genus and species of male cones of coniferophyte from the Lower Permian (Artinskian and Kungurian) deposits of the Urals, Russia is described: Uralostrobus voltzioides Naugolnykh nov. gen., nov. sp. The cone shows characters typical of some representatives of conifers belonging to the order Voltziales: more or less isometrical bracts of rhombic shape, prolonged sporangia with attenuate apices, and bisaccate pollen of Illinites-type. General information on the associated female seed scales and vegetative leafy shoots is given as well.     

Morphological and ontogenetic studies on southern African podocarps. Shoot apex morphology and ovuliferous cone initiation

STOFFBERG, E., 1991. Morphological and ontogenetic studies on southern African podocarps. Shoot apex morphology and ovuliferous cone initiation. Four species of Podocarpus indigenous to southern Africa were investigated. The morphology of the primordium of the female cone is compared with that of the shoot apex. Rhythmic growth occurs in Podocarpus. The external morphology of bud scales protecting dormant shoot apices is described and illustrated. Female strobili of the three species of section Podocarpus studied are initiated in the axils of euphylls during the spring growth flush as laterally flattened triangular structures. The axillary position of a female cone indicates that it is a modified shoot. The first two cone bracts (prophylls) are formed approximately at right angles to the subtending bract (one or both are fertile), while the 3rd and 4th bracts originate on the anterior and posterior sides of the strobilus respectively. Two to four bracts per cone are formed, not in pairs–the phyllotaxis is spiral. In P.falcatus primordia of female strobili and vegetative branches could be distinguished only after emergence of the seed scale complex. Based on cell differentiation, well-defined cytological zones can be distinguished in the shoot apex and it is classified as being of the Abies-Cryptomeria-lype. Meristematic zones of cone primordia and vegetative branches are basically similar, although the former are less well defined. No gradual transition from a vegetative to a reproductive apex could be identified and it would seem that the fate of axillary buds are determined at the time of their origination or even before.     

MORE EVIDENCE FOR CONIFER DIVERSITY IN THE UPPER TRIASSIC OF NORTH CAROLINA

An ovulate strobilus from the Upper Triassic Deep River Basin, North Carolina, has helically arranged, loosely aggregated, elongated, spatulate bracts with axillary ovule-bearing appendages with about 8–10 ovules attached in two lateral rows, with outwardly directed micropyles. The axillary ovuliferous appendage is homologous with the voltzialean fertile dwarf shoot, but probably not directly evolved from it. More credible is a suggested origin from a completely fertile axillary appendage such as that of the Lower Permian Trichopitys. The occurrence of this cone, Metridiostrobus palissyaeoides, gen. and sp. nov., along with Compsostrobus neotericus and Voltzia andrewsii, reflects considerable diversity among conifer ovulate cones during the Upper Triassic.     

The seed cone Eathiestrobus gen. nov.: Fossil evidence for a Jurassic origin of Pinaceae

? Premise of the study: Pinaceae and nonpinoid species are sister groups within the conifer clade as inferred from molecular systematic comparisons of living species and therefore should have comparable geological ages. However, the fossil record for the nonpinoid lineage of extant conifer families is Triassic, nearly 100 million years older than the oldest widely accepted Lower Cretaceous record for Pinaceae. An anatomically preserved fossil conifer seed cone described here extends the stratigraphic range of Pinaceae nearly 30 million years, thus reducing the apparent discrepancy between evidence from the fossil record and inferences from systematic studies of living species. ? Methods: Material was prepared as serial thin sections by the cellulose acetate peel technique, mounted on microscope slides, and viewed and photographed using transmitted light. ? Key results: A large cylindrical cone consisting of bract-scale complexes that diverge from the cone axis in a helical phyllotaxis has bracts and scales that separate from each other in the midregion and are of equal length and of nearly equal width. The cone has two inverted and winged seeds that are attached to the adaxial surface of each cone scale and, thus, represents an early member of the Pinaceae. ? Conclusions: Eathiestrobus mackenziei gen. et sp. nov. extends the fossil record for well-documented members of the family Pinaceae from the Lower Cretaceous to the Kimmeridgian Stage of the Upper Jurassic. This species also clarifies the set of characters that are diagnostic for seed cones of Pinaceae and reveals possible plesiomorphic characters for seed cones of the family.     

CONE DEVELOPMENT IN LIBOCEDRUS (CUPRESSACEAE)—PHENOLOGICAL AND MORPHOLOGICAL ASPECTS

Cones in Libocedrus plumosa are initiated in New Zealand in February (late summer) and continue to develop through winter. The ultimate pair of bracts protrude and continue extension growth while the apex remains flat. Ovules are initiated in two pairs in July on the cone apex (i.e., are axial in origin), alternate with the upper two pairs of bracts. Ovule differentiation proceeds rapidly to the stage of pollination; the cone apex may develop further as a short columella. Soon after ovule initiation an adaxial ligulelike outgrowth of each member of the upper two pairs of bracts is initiated, that of the ultimate pair being broader than that of the lower pair. By intercalary growth of each ligule base an enlarged structure is developed, displacing the bract into a lateral position and forming the four scales that enclose the developing seeds in a valvate manner. Cone and seed maturation follows with seed dispersal in March, approximately 1 year after cone initiation. The results show that there is no morphologically discrete ovuliferous scale, and there is no ontogenetic fusion of discrete separate structures. The vascular system of the scale complex develops after the ovules are initiated and forms a single series of vascular bundles with inversely oriented xylem and phloem; this and other histological changes are the result of the activity of the intercalary growth process and do not relate to primary structures. The results are discussed in relation to existing knowledge of cone development in Cupressaceae, in which axially borne ovules are common.     

Shoot apex and spathella: two problematical structures of Podostemaceae–Podostemoideae

The presence of a shoot apex and shoot apical meristem (SAM), said to be absent in subfamily Podostemoideae (Podostemaceae), is confirmed for Marathrum utile and M. foeniculaceum. The vegetative shoot axis is terminated by a small group of meristematic cells which are surrounded by the tissue of the adnate bases of foliage leaves. The slightly bulged tip of the shoot apex is embraced by the youngest leaf, facing the apex with its adaxial side. The study also refers to the spathella, a cup-shaped structure covering obligatorily the young flower bud in Podostemoideae. The occurrence of two separate peaks in the young spathella of M. foeniculaceum supports the view that the spathella is formed by two fused bracts (hypsophylls). The two bracts are perpendicular to the distichous foliage leaves below the spathella. The scaly leaflet on the spathella of A. latifolia apparently does not represent a rudimentary blade of the spathella, but is interpreted as a separate bract. The occasional occurrence of scales below or above the spathella points to a reduction of bracts that were originally present in greater number on the pedicels.     

A PENNSYLVANIAN CALAMITEAN CONE WITH ELATERITES TRIFERENS SPORES

In 1943 L. R. Wilson described some scattered elater-bearing spores found in a Middle Pennsylvanian coal ball from What Cheer, Iowa, as Elaterites triferens. The spores, averaging 60 μ in diameter, with a trilete scar on the proximal surface and three conspicuous elaters attached to their distal surface, have now been found in a fragment of a cone from the same locality. The cone is similar to Calamostachys in having whorls of sporangiophores, each with four adaxial sporangia, and some secondary xylem at the nodes, but it possibly differs in lacking sterile bracts.     

SILICIFIED PINUS REMAINS FROM THE MIOCENE OF WASHINGTON

Silicified leaves, dwarf shoots, pollen cones, and seed cones of Pinus from a Late Miocene chert bed within the Yakima Basalt Formation near Yakima, Washington are interpreted as coming from a single new species, P. foisyi. The needles and dwarf shoots are those of a three-needle pine. The needles contain two to four medial resin canals, a biform hypodermis, and endodermal cells with uniformly thickened walls. The pollen cones are ellipsoidal and about 1 cm long, and many contain bisaccate pollen grains. The seed cones are at least 6 cm long and are slightly asymmetrical. The cone axis has a broad sclerotic outer cortex, and the seed wing extends from a thick parenchymatous base. The scale apex bears a conspicuously swollen projection. The foliage and seed cones are identifiable with the Subgenus Pinus, Section Pinus, Subsection Oocarpae independently of one another, and together indicate a fossil species related to the modem Californian closed cone pines. Pinus foisyi represents one of the earliest occurrences of cone asymmetry associated with this group. However, cone serotiny characteristic of the modem species appears to have evolved after the Late Miocene.     

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).     

Cones structure and seed traits of four species of large‐seeded pines: Adaptation to animal‐mediated dispersal

Seed dispersal selection pressures may cause morphological differences in cone structure and seed traits of large‐seeded pine trees. We investigated the cone, seed, and scale traits of four species of animal‐dispersed pine trees to explore the adaptations of morphological structures to different dispersers. The four focal pines analyzed in this study were Chinese white pine (Pinus armandi), Korean pine (P. koraiensis), Siberian dwarf pine (P. pumila), and Dabieshan white pine (P. dabeshanensis). There are significant differences in the traits of the cones and seeds of these four animal‐dispersed pines. The scales of Korean pine and Siberian dwarf pine are somewhat opened after cone maturity, the seeds are closely combined with scales, and the seed coat and scales are thick. The cones of Chinese white pine and Dabieshan white pine are open after ripening, the seeds fall easily from the cones, and the seed coat and seed scales are relatively thin. The results showed that the cone structure of Chinese white pine is similar to that of Dabieshan white pine, whereas Korean pine and Siberian dwarf pine are significantly different from the other two pines and vary significantly from each other. This suggests that species with similar seed dispersal strategies exhibit similar morphological adaptions. Accordingly, we predicted three possible seed dispersal paradigms for animal‐dispersed pines: the first, as represented by Chinese white pine and Dabieshan white pine, relies upon small forest rodents for seed dispersal; the second, represented by Korean pine, relies primarily on birds and squirrels to disperse the seeds; and the third, represented by Siberian dwarf pine, relies primarily on birds for seed dispersal. Our study highlights the significance of animal seed dispersal in shaping cone morphology, and our predictions provide a theoretical framework for research investigating the coevolution of large‐seeded pines and their seed dispersers.     

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.     

A new species of Williamsonia from the Upper Triassic Chinle Formation of New Mexico

Williamsonia nizhonia sp. nov., the first undoubted bennettitalean flower known from the Chinle Formation of Upper Triassic age in the south - western United States, is described in detail. The species is based on a single vertically compressed specimen collected from the Lower Red Member of the Chinle Formation near Fort Wingate in west-central New Mexico. It is rather small, the gynoecium is about 5 mm in diameter and is surrounded by a whorl often persistent sterile bracts about 1–5 cm long. The cuticles of the bracts and interseminal scales are 1 to 2 u thick. Stomata are only slightly sunken on the cuticles of the bracts and interseminal scales. Only a few hairs occur on the bracts. Williamsonia nizhonia cannot be attributed with any degree of confidence to either of the two bennettitalean leaves presently known in the Chinle flora.     

Petrocodon retroflexus sp. nov. (Gesneriaceae) from a karst cave in Guizhou,China

Petrocodon retroflexus Q. Zhang & J. Guo, a new species of Gesneriaceae from Guizhou, China, is described and illustrated. The new species is morphologically similar to Petrocodon viridescens W. H. Chen, Mich. Möller & Y. M. Shui, but differs by its leaf blade being ovate, broadly ovate to elliptic, 8–20 × 5–15 cm and densely pilose on both surfaces, narrowly triangular, 9 mm long, densely pilose bracts, white corolla that is decurved near the middle, with adaxial lip shallowly 4‐partitioned and retroflexed, and pistil ca 1.3 cm long and densely pilose and glandular‐pilose.     

Implications of fossil conifers for the phylogenetic relationships of living families

Fossils have played a central role in our understanding of the evolution of conifers. Interpretation of the seed cone as a compound strobilus and the homologies of the ovuliferous scales of modern conifers with the axillary dwarf shoot of Pennsylvanian forms are based on fossils. Similarly, early evolutionary trends involving the reduction, fusion, and planation of the fertile and sterile elements of the axillary dwarf shoot, leading to structures characteristic of modern families, are documented in Late Permian and Triassic conifers. However, a phylogeny elucidating the derivation of modern families from fossil forms based on shared derived features has been elusive. The present cladistic treatment using 11 characters of ovulate cones and one of pollen grains suggests three phylogenetic groups of Late Paleozoic conifers, represented loosely by the Emporicaceae, Utrechtiaceae, and Majonicaceae of Mapes and Rothwell. The Taxaceae appears to have diverged from ancestors within the Utrechtiaceae, whereas the other modern families owe their origins to the Majonicaceae. The origin of the Taxodiaceae appears to have been biphyletic.Taxodium, Cupressus andSciadopitys are strongly linked toDolmitia of the Majonicaceae, butCryptomeria, Cunninghamia andAraucaria are grouped together and diverge basal to the former taxa.Pinus branches from a position basal to the known genera of the Majonicaceae and all modern families except the Taxaceae.Podocarpus also diverges basal toMajonica but may share an ancestor with this genus;Cepahalotaxus diverges basal to theDolmitiaPseudovoltzia subclade but distal toMajonica. Similarly, the Cheirolepidiaceae originated from basal members of the Majonicaceae and shows no close phylogenetic relationship with any modern family. Except for a strong linkage betweenCycadocarpidium and theAraucariaCunninghamia subclade, genera of the Voltziaceae appear to have branched more or less independently from within the Majonicaceae and show no strong affinity with modern conifers. Thus differences between modern conifer families are due mainly to their divergence from different Paleozoic ancestors.     

A new species of the extinct genus Austrohamia (Cupressaceae s.l.) in the Daohugou Jurassic flora of China and its phytogeographical implications

Abstract A new conifer, Austrohamia acanthobractea, sp. nov., is described from the Jurassic Daohugou flora, Inner Mongolia Autonomous Region, China. The material consists of impressions represented by well‐preserved leafy twigs and branches as well as ovulate cones. Leafy shoots with at least two orders of branching; ultimate branchlets alternate or sub‐opposite with helically arranged leaves, decurrent at base with distal rounded tip; dorsiventrally flattened and univeined. Ovuliferous cones elliptical, less than 1 cm long, terminally borne on ultimate and penultimate branches, composed of helically arranged bracts with ovules disposed on their adaxial surfaces. The presence of similar, if not identical taxa, on both sides of the Pacific indicates the cosmopolitan distribution of primitive Cupressaceae between East Asia (Eurasia) and South America in the Pangaea.     

PINUS AVONENSIS,A NEW SPECIES OF PETRIFIED CONES FROM THE OLIGOCENE OF WESTERN MONTANA

Fossils from the Oligocene of western Montana described in this treatment are the first structurally preserved ovulate cones of Pinus to be reported from the Tertiary of North America. They are about 5.5 cm long and have a maximum diam of 2.5 cm. Numerous scales are arranged spirally around the axis and each scale bears two winged seeds. The bract subtending the ovuli-ferous scale is 3-4 mm long and is free from the scale throughout its length. The pith and cortex of the axis are constructed of thick-walled parenchyma cells and 18-21 resin canals occur at the inner edge of the cortex. Resin canals entering the base of the ovuliferous scale are restricted to the abaxial side with vascular tissues occupying the adaxial side. Vascular strands near the tip of the scale are strongly rounded on the adaxial or phloem side. At the abaxial side of the tip of the ovuliferous scale is a broadly rhomboidal apophysis with a raised umbo that terminates in a short spine. The fossils differ from the several Recent cones examined in having fewer resin canals and biseriate rays in the secondary xylem of the cone axis. The shape of the cone, its anatomical features, and the morphology of the tip of the cone scale indicate affinity with the subgenus Diploxylon.     

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.     

Rungia sinothailandica sp. nov. (Acanthaceae) from China and Thailand

Rungia sinothailandica (Acanthaceae), a new species from Yunnan, China and Chiang Rai, Thailand is described and illustrated. A colour plate, line drawing and distribution map of R. sinothailandica are provided. Rungia sinothailandica is similar to R. pinpienensis H. S. Lo, but differs in the broadly ovate sterile bracts and obovate‐elliptic fertile bracts, the crispate and tawny bracts margin, the 2‐lobed upper lip of the corolla and puberulent capsule. It is also similar to R. burmanica (C. B. Clarke) B. Hansen, but is easily distinguished by pubescent stems and leaves, the cymbiform‐oblong bracteoles and the 2‐lobed upper lip of corolla.     

DEVELOPMENTAL ANATOMY OF JUVENILE AND ADULT SHOOTS OF MARCGRAVIA RECTIFOLIA L

Marcgravia rectifolia L. is a dimorphic vine having distinct juvenile and adult shoots. The juvenile shoot is a climber characterized by an orthotropic growth habit, a flattened stem, adventitious roots, and ovate leaves. The adult shoot, on the other hand, possesses a plagiotropic growth habit, has a cylindrical stem, few or no adventitious roots, and lanceolate leaves. Both phases have distichous phyllotaxy, however the plastochron is shorter for the adult phase than for the juvenile. Internode elongation occurs earlier for adult shoots than for juvenile shoots. Cytological analyses show the flattened stem of the juvenile results from differential production of cells, especially in the pith region. On the other hand, internodes of the adult phase are longer than juvenile internodes, a result of more cells produced rather than longer cells. In juvenile stems a perivascular band of elongated fibers develops, while in adult stems this band consists of brachyosclereids. Both phases undergo secondary growth and have non-storied cambia. Cambial activity begins in the 6th internode of each phase. As secondary growth proceeds, the adult stem produces much more xylem than juvenile stems of the same age. Adventitious roots produced in the juvenile stem are located in vertical rows at the “corners” of flattened stems and are attachment structures aiding the climbing habit of this vine. Phase changes occur regularly in this species. The juvenile phase usually transforms into the adult, however the adult phase can spontaneously revert back into the juvenile phase. The anatomical features and the phase changes are discussed and compared to Hedera helix, a vine whose phase changes have been studied in some detail. It is suggested that the anatomical features of Marcgravia rectifolia L. including its phase changes, may provide an alternative system to study physiological changes similar to those done with Hedera helix.