Staminate Inflorescences Research Articles

New Taxa and Combinations in Protium Burm. f. Studies in Neotropical Burseraceae VI

Revision ofProtium in eastern Amazonia and the Guianas yielded one new section, three new species, three new subspecies, and five new combinations in the genus. SectionSarcoprotium Daly is distinguished principally by the cucullate petals with clawed bases and usually with a dorsal thickening produced vertically as an appendage; staminate inflorescences with a few 3-merous flowers; thecae of the anthers completely separated by the connective and the dehiscence latero-introrse; and fruit ellipsoid when only one pyrene develops.

A New Species of Palaeocarpinus (Betulaceae) Based on Infructescences, Fruits, and Associated Staminate Inflorescences and Leaves from the Paleocene of Alberta, Canada

About 2,000 specimens of infructescences, cymules, fruits, bracts, staminate inflorescences with in situ pollen grains, and leaves assignable to Betulaceae have been collected from the Munce's Hill locality (Paleocene, Paskapoo Formation), Joffre, Alberta. Infructescences are composed of many cymules, each cymule consisting of two fruits. Each fruit is an oval nutlet surrounded by two equal-sized bracts. Bract form varies considerably with respect to size and marginal dissection. Bracts are as deeply dissected and variable as the British type specimen of Palaeocarpinus laciniata Crane from the Paleocene of southern England but usually have one or two lobes instead of several lobes. A short pedicel is present at the base of the fruit, a feature not reported in the British specimens. Furthermore, nutlets have numerous longitudinal striations rather than three longitudinal ribs on their surfaces. Based on the characteristics of nutlets and bracts, these specimens are described as P. joffrensis Sun et Stockey sp. nov. Associated staminate inflorescences are compound catkins composed of many cymules, each consisting of a triangular primary bract, ovate secondary bracts, and numerous stamens. Elongate pollen sacs contain triporate pollen grains with rugulate ornamentation and numerous Ubisch bodies. Transmission electron microscopy reveals a thin foot layer, granular interstitium, and a thick tectum with microchannels. The presence of secondary bracts in inflorescences and aperture characters of the pollen grains show similarity to the genus Corylus. Associated leaves, also resembling Corylus, are ovate to elliptic, with acuminate to attenuate apices, cordate bases, and toothed margins. Six to nine pairs of secondary veins enter the primary teeth with vein endings bending toward the leaf base. Prominent abmedial branches from the secondary veins enter subsidiary teeth. Tertiary and quaternary veins come together at the sinuses, an important feature of Betulaceae. Based on their association and taxonomic affinities, both leaves and-staminate inflorescences are thought to represent detached organs of P. joffrensis.

Early ontogenetic development of the pistillate inflorescence in a diploid perennial teosinte (Zea diploperennis, Poaceae)

CAMARA-HERNANDEZ J. & GAMBINO, S., 1991. Early ontogenetic development of the pistillate inflorescence in a diploid perennial teosinte (Zea diploperennis, Poaceae). The early ontogeny of pistillate inflorescences of %ea diploperennis in plants grown at the latitude of Buenos Aires, Argentina, is investigated using the scanning electron microscope. The pattern of development of the inflorescence is similar to that in staminate and mixed inflorescences, starting with the formation of a pair of spikelets from a common branch primordium initiated in the axil of a bract on the ear axis. This bract arrests its development and aborts early. After initiation of an outer glume on both spikelet primordia, the pedicellate spikelet arrests its growth and aborts resulting in the mature inflorescence having two rows of solitary spikelets arranged distichally. This is significantly different from the pattern observed by other authors in plants grown in different environments (such as in natural populations in Mexico).

Sex expression in fruiting male vines of kiwifruit

In three canes on each of five fruiting male kiwifruit vines (A. deliciosa var. deliciosa (A. Chev) Liang and Ferguson), staminate and bisexual flowers were interspersed, so that staminate, bisexual and mixed inflorescences were found. Further variation in inflorescence composition resulted from the abortion of flower buds prior to anthesis. These two sources of variation, in combination, resulted in 19 inflorescence patterns, which varied substantially in frequency among and within vines. Some tendencies were determined. In particular, most of the inflorescences had retained their terminal flower, whereas just over half had retained one or both primary lateral flowers, and in two-thirds of the inflorescences retaining a terminal flower, this was bisexual. The five vines ranged in bisexual flower frequency from 40% to 70%. Phenotypic Gender (P) estimates are given for each vine, based on the frequencies of staminate and bisexual flowers from three canes per vine. Flower development, lability in sex expression and the use of P estimates as part of a selection index in breeding for hermaphrodite kiwifruit cultivars are discussed.

Platanaceous plants from the Paleocene of Alberta, Canada

A new platanaceous plant is described from the Joffre Bridge locality from the Paleocene of western Canada. The plant is based upon a suite of distinctive platanaceous remains. These include: foliage leaves that resemble Platanus nobilis Newberry, pistillate inflorescences and infructescences assigned to a new species of Macginicarpa Manchester, M. manchesteri Pigg et Stockey, sp. nov., staminate inflorescences assigned to a new species of Platananthus Manchester emend. Friis et al., P. speirsae Pigg et Stockey, sp. nov., isolated groups of stamen clusters containing platanaceous pollen, and young seedlings in several stages of development. Based on their exclusive co-occurrence at a single locality these disarticulated organs are thought to represent the same platanaceous plant. The reconstruction of the Joffre plane tree is the second “whole plant” reconstruction from the Joffre Bridge locality. Along with the cercidiphyllaceous Joffrea speirsii Crane and Stockey, the Joffre plane tree can be included among the best known Paleocene angiosperms.

Qualitative and Quantitative Analysis of Carbohydrates in Leaf Exudate of the Short-day Plant, Xanthium strumarium L. during Floral Transition

Intact plants of Xanthium were induced to flower by a single 16-h long night (LN) or were kept vegetative either by continuous 18-h long days (LD) or by a 5-min night break (NB) in the middle of a single LN of 16 h. We first established that intact Xanthium plants behave as unifoliated plants with regard to sensitivity to the inductive night, translocation of the floral stimulus and rate of development of the terminal staminate inflorescence. Using HPLC and refractometry, carbohydrates in the leaf exudate, obtained by the EDTA-method, were analysed in response to the 3 photoperiodic treatments either inducing flowering or keeping the plants at the vegetative stage. Sucrose was the major sugar detected. Its content in the phloem sap increased in LN induced and NB vegetative control plants as compared with LD vegetative control plants. These results suggest that while the increase of sucrose export out of the leaves could be related to floral transition, it does not suffice to trigger the complete sequence of floral evocation.

ANATOMY AND ASPECTS OF DEVELOPMENT OF THE STAMINATE INFLORESCENCES AND FLORETS OF SEVEN SPECIES OF ALLOCASUARINA (CASUARINACEAE)

The morphology, ontogeny, and vascular anatomy of the staminate inflorescences and florets of seven species of Allocasuarina are described. The generally terminal but open‐ended inflorescences occur on monoecious or staminate dioecious trees and consist of whorls of bracts, each subtending a sessile axillary floret. Each floret consists of one terminal stamen with a bilobed, tetrasporangiate anther enclosed typically by cuculliform appendages, commonly considered bracteoles, an inner median pair and an outer lateral pair. The mature stamen is exerted, the anther is basifixed and is extrorsely dehiscent. In early development of a male inflorescence very little internodal elongation occurs and enclosing cataphylls appear. The inflorescence apex is a low dome with a uniseriate tunica and a small group of central corpus cells. Bract primordia are initiated by periclinal divisions of C1 followed by further divisions of the corpus and anticlinal divisions in the tunica. The bracts are epinastic and become gamophyllous except apically by cell divisions in both sides of each primordium. Stomata are restricted to the axis furrows and the abaxial tips of the bracts. The axillary florets arise in acropetal succession initiated by periclinal divisions in C1 accompanied by anticlinal divisions in the tunica. The lateral floral appendages are also initiated by C1 followed by anticlinal divisions in the tunica. They become adnate basally later with the subtending bract. The median sterile appendages are initiated in a manner similar to the initiation of the outer appendages. The stamen is initiated by divisions in the outer layers of the corpus and in the tunica, and then develops first by apical growth followed by intercalary growth. The vascular system of the inflorescence is identical to that of the vegetative stem. Each floret is supplied by a single bundle that has its source in a branch from each of the two traces supplying a bract. Six bundles arise from the floral bundle; four of these terminate in the base of the stamen and two form an amphicribal bundle that supplies the anther. Pollen is binucleate, 3‐ to 7‐porate. The exine is tegillate.

Within- and Among-Tree Variation in Flower and Fruit Production in Two Species of Carya (Juglandaceae)

The patterns of variability in the production of staminate inflorescences, pistillate flowers, and fruits for Carya ovata (Mill.) K. Koch and C. tomentosa (Poir.) Nutt. at Hutcheson Memorial Forest (Somerset County, New Jersey) were examined over a four-year period. We sought to determine 1) the patterns of variability in flowering and fruiting (within-trees, among-trees, and between-years), 2) if variable flowering might account for observed nut-bearing patterns, and 3) what were the relative contributions of intrinsic (genetic) and/or extrinsic (environmental) factors in determining flower production and fruit set. In general, our fine-scale analysis of shoots within canopies did not reveal a distinct mast fruiting pattern. While the number of male and female flowers varied significantly (among trees and between years), fruit set was not markedly affected. Variability of flowering and fruiting among shoots within trees was low. Both flowering and fruiting were observed to have a strong genetic and/or microenvironmental basis; however, flowering appeared more plastic and thus more sensitive to yearly environmental vagaries than did fruiting. Favorable environmental conditions at the time of flower differentiation may result in increased flower production; but, this does not necessarily result in increased fruit set. Many pistillate flowers abscise around the time of pollination and fertilization, apparently adjusting fruit set to available shoot resources. Approximately 50% of the pistillate flowers of both species fail to set fruit. Overall, individual trees exhibit their own flowering and fruiting schedules, suggesting the need to account for this level of variability in future studies of mast fruiting.

WITHIN‐ AND AMONG‐TREE VARIATION IN FLOWER AND FRUIT PRODUCTION IN TWO SPECIES OF CARYA (JUGLANDACEAE)

The patterns of variability in the production of staminate inflorescences, pistillate flowers, and fruits for Carya ovata (Mill.) K. Koch and C. tomentosa (Poir.) Nutt. at Hutcheson Memorial Forest (Somerset County, New Jersey) were examined over a four‐year period. We sought to determine 1) the patterns of variability in flowering and fruiting (within‐trees, among‐trees, and between‐years), 2) if variable flowering might account for observed nut‐bearing patterns, and 3) what were the relative contributions of intrinsic (genetic) and/or extrinsic (environmental) factors in determining flower production and fruit set. In general, our fine‐scale analysis of shoots within canopies did not reveal a distinct mast fruiting pattern. While the number of male and female flowers varied significantly (among trees and between years), fruit set was not markedly affected. Variability of flowering and fruiting among shoots within trees was low. Both flowering and fruiting were observed to have a strong genetic and/or microenvironmental basis; however, flowering appeared more plastic and thus more sensitive to yearly environmental vagaries than did fruiting. Favorable environmental conditions at the time of flower differentiation may result in increased flower production; but, this does not necessarily result in increased fruit set. Many pistillate flowers abscise around the time of pollination and fertilization, apparently adjusting fruit set to available shoot resources. Approximately 50% of the pistillate flowers of both species fail to set fruit. Overall, individual trees exhibit their own flowering and fruiting schedules, suggesting the need to account for this level of variability in future studies of mast fruiting.

Effects of 3-(p-chlorophenyl)-6-methoxy-s-triazine-2,4 (1H, 3H) dione triethanolamine (DPX-3778) treatment on the floral development of maize

In a series of experiments to determine the physiological effects of a triazanone antidehiscence chemical, 3-(p-chlorophenyl)-6-methoxy-s-triazine-2,4 (1H, 3H) dione triethanolamine (DPX-3778), sex determination of the tassels of corn (Zea mays subsp. mays) was altered depending on the concentration and timing of application. Multiple applications of 0.005% (w/v) DPX-3778 to the leaf sheath of maize plants, or the addition of 1 ppm DPX-3778 to hydroponic growth medium, approximately 4 weeks before anthesis, caused reversion of staminate inflorescences to pistillate inflorescences. In addition to the normally developed gynoecium of the upper floret, DPX-3778 treatment resulted in the full development of the lower floret gynoecium in ear spikelets. These results could be duplicated in Northern Teosinte (Zea mays subsp. mexicana, race Nobogame). DPX-3778 could thus be useful for investigating the cellular and developmental physiology of stamens and gynoecia in corn and other monoecious grass species.

Betula leaves and reproductive structures from the Middle Eocene of British Columbia, Canada

Fossil angiosperm leaves from the Middle Eocene Allenby Formation, at One Mile Creek near Princeton, southern British Columbia, are described and assigned to Betula leopoldae Wolfe & Wehr. Morphological details of associated infructescences, fruits, staminate inflorescences, and pollen are also very similar to those of extant Betula. Based on association evidence and independently determined systematic relationships, we suggest that the vegetative and reproductive structures were produced by a single fossil species. Combined information from all the organs available suggests that this Eocene Betula is most closely related to species in section Eubetula, subsection Costatae of the extant genus. Material from One Mile Creek constitutes the earliest fully documented record of the genus Betula based on both vegetative and reproductive structures. In the context of the fossil history of the Betulaceae as a whole, it indicates that the two extant genera of the Betuleae, Alnus and Betula, were clearly differentiated by the Middle Eocene.

FLORAL DEVELOPMENT IN MYRISTICA (MYRISTICACEAE)

Myristica fragrans and M. malabarica are dioecious. Both staminate and pistillate plants produce axillary flowering structures. Each pistillate flower is solitary, borne terminally on a short, second‐order shoot that bears a pair of ephemeral bracts. Each staminate inflorescence similarly produces a terminal flower and, usually, a third‐order, racemose axis in the axil of each pair of bracts. Each flower on these indeterminate axes is in the axil of a bract. On the abaxial side immediately below the perianth, each flower has a bracteole, which is produced by the floral apex. Three tepal primordia are initiated on the margins of the floral apex in an acyclic pattern. Subsequent intercalary growth produces a perianth tube. Alternate with the tepals, three anther primordia arise on the margins of a broadened floral apex in an acyclic or helical pattern. Usually two more anther primordia arise adjacent to each of the first three primordia, producing a total of nine primordia. At this stage the floral apex begins to lose its meristematic appearance, but the residuum persists. Intercalary growth below the floral apex produces a columnar receptacle. The anther primordia remain adnate to the receptacle and grow longitudinally as the receptacle elongates. Each primordium develops into an anther with two pairs of septate, elongate microsporangia. In pistillate flowers, a carpel primordium encircles the floral apex eventually producing an ascidiate carpel with a cleft on the oblique apex and upper adaxial wall. The floral ontogeny supports the morphological interpretation of myristicaceous flowers as trimerous with either four‐sporangiate anthers or monocarpellate pistils.

Floral Development in Myristica (Myristicaceae)

Myristica fragrans and M. malabarica are dioecious. Both staminate and pistillate plants produce axillary flowering structures. Each pistillate flower is solitary, borne terminally on a short, second-order shoot that bears a pair of ephemeral bracts. Each staminate inflorescence similarly produces a terminal flower and, usually, a third-order, racemose axis in the axil of each pair of bracts. Each flower on these indeterminate axes is in the axil of a bract. On the abaxial side immediately below the perianth, each flower has a bracteole, which is produced by the floral apex. Three tepal primordia are initiated on the margins of the floral apex in an acyclic pattern. Subsequent intercalary growth produces a perianth tube. Alternate with the tepals, three anther primordia arise on the margins of a broadened floral apex in an acyclic or helical pattern. Usually two more anther primordia arise adjacent to each of the first three primordia, producing a total of nine primordia. At this stage the floral apex begins to lose its meristematic appearance, but the residuum persists. Intercalary growth below the floral apex produces a columnar receptacle. The anther primordia remain adnate to the receptacle and grow longitudinally as the receptacle elongates. Each primordium develops into an anther with two pairs of septate, elongate microsporangia. In pistillate flowers, a carpel primordium encircles the floral apex eventually producing an ascidiate carpel with a cleft on the oblique apex and upper adaxial wall. The floral ontogeny supports the morphological interpretation of myristicaceous flowers as trimerous with either four-sporangiate anthers or monocarpellate pistils.

Vegetative and Reproductive Morphology of an Extinct Plane Tree (Platanaceae) from the Eocene of Western North America

An extinct type of plane tree, common in the Middle to Late Eocene of Oregon, is reconstructed as a whole plant on the basis of repeated co-occurrence of isolated platanaceous organs at numerous localities. It is described in detail on the basis of leaf architecture, petiole and stem anatomy, pistillate inflorescence morphology, fruit anatomy, staminate inflorescence morphology, and in situ pollen morphology, rendering it the most completely documented fossil angiosperm species. The leaves, Macginitiea angustiloba (Lesq.) comb. nov., are relatively large, with five to seven palmately arranged lobes and palinactinodromous venation. They resemble those of some modern Platanus species except in features associated with a narrower angle between adjacent primary veins. The petioles are basally expanded and hollow and appear to have enclosed the axillary buds, as in most extant Platanus species. Inflorescences are borne as globose heads along separate staminate and pistillate axes. The pistillate inflorescenc...

Morphology and Development of Pistillate Inflorescences in Extant and Fossil Cercidiphyllaceae

Morphology and Development of Pistillate Inflorescences in Extant and Fossil Cercidiphyllaceae

Studies in the Araliaceae of Nicaragua, and a New Widespread Species of Oreopanax

Studies in the Araliaceae of Nicaragua, and a New Widespread Species of Oreopanax

The biomass and nutritive potential of Vallisneria americana Michx in navigation pool 9 of the upper Mississippi river

Vallisneria americana Michx (wild celery) was studied to determine the biomass and nutritive potential of all morphological structures. A 2.6-ha stand of uniform V. americana was sampled during the summer and autumn of 1980, and the spring and summer of 1981 in the southern portion of Navigation Pool 9 of the Upper Mississippi River. The maximum production rate of 3.2 g m −2 day −1 was coincident with rapid rosette production and flowering, and occurred mid- to late-July 1980. The maximum biomass of 217.3 g dry wt. m −2 was on 1 September 1980, when fruit development was also at a maximum. Leaves composed 60–70% of the summer biomass; winter buds constituted all of the winter biomass. Winter buds and fruits had the greatest nutritive potentials. Both organs contained relatively high dry matter concentrations and were low in ash (less than 10%) and fiber content. The potentially-digestible ash-free non-cell-wall fraction (NCF) was composed of an average of 75.7 and 82.2% of the dry weight of fruits and winter buds, respectively. In contrast, the nutritive potential of leaves, rootstocks, peduncles and stolons was reduced because of high moisture (less than 8% dry matter), ash and fiber concentrations. Staminate inflorescences and pistillate flowers were high in crude protein (averaged 21.8% and 16.1% of the dry-weight, respectively) and ash-free non-cell-wall fractions, but they accounted for only 2.7% of the plant biomass. The maximum calorific content of V. americana was approximately 3200 kJ m −2 at peak biomass on 1 September 1980.

Growth and reproductive biology of Joffrea speirsii gen. et sp. nov., a Cercidiphyllum-like plant from the Late Paleocene of Alberta, Canada

Six kinds of angiosperm compression fossils are described from the Paskapoo Formation (Late Paleocene) at Joffre Bridge near Red Deer, Alta. Pistillate inflorescences with attached carpels, folliculate infructescences, seeds, seedlings, leaves, and shoots arc all assigned to Joffrea speirsii gen. et sp. nov. Crane and Stockey. Evidence for treating the different organs under a single binomial includes attachment of inflorescences and leaf petioles to long and short shoot systems, morphological intermediates between carpels and follicles, follicles preserved expelling seeds, seeds preserved during germination, stages in seedling development, similarity between seedling and adult foliage, and constant field association. Joffrea is similar in many respects to the widespread Upper Cretaceous and early Tertiary fossil Nyssidium arcticum (Heer) Iljinskaja. Comparison of Joffrea to the extant genera Cercidiphyllum Siebold et Zuccarini, Trochodendron Siebold et Zuccarini, and Tetracentron Oliver indicates a close relationship to Cercidiphyllum; and Joffrea is interpreted as an extinct representative of the family Cercidiphyllaceae. The fossil material clarifies morphological interpretations of the pistillate reproductive structures in extant Cercidiphyllum. The probable staminate inflorescences of Joffrea, are also similar to extant Cercidiphyllum. They are budlike and composed of 10–20 bracts, some of which have stamens in their axils. Pollen has not been recovered from the anthers. Pistillate inflorescences developed from axillary buds on the short shoots and were probably wind-pollinated. The production of numerous small winged seeds, epigeal germination, and the preservation of large numbers of in situ seedlings suggest that Joffrea speirsii and similar extinct Upper Cretaceous and early Tertiary species may have been "weedy" plants capable of rapidly colonizing open floodplain habitats.

The Platycarya Perplex and the Evolution of the Juglandaceae

We report on the leaves, fruits, inflorescences, and pollen of two fossil species in the genus Platycarya. The association of these dispersed organs has been established by their repeated co-occurrence at a large number of localities, and for two of the organs (fruit and pistillate inflorescence, and pollen and staminate inflorescence) by apparent organic attachment of compression fossils. Each of the two species can be distinguished by characteristics of all the known megafossil organs. We also review the fossil record of dispersed platycaryoid fruits and inflorescences, recognizing three additional species of Platycarya and two of Hooleya. Two of the fossil Platycarya species are morphologically very different from the living Platycarya strobilacea Sieb. et Zucc., but they show the diagnostic features of the genus. Hooleya is a generalized member of the Platycaryeae that is probably close to the ancestry of Platycarya. The two Platycarya species known from multiple organs provide a remarkable example of mosaic evolution in which fertile and foliar structures have attained different levels of morphological specialization. The leaves, often considered the most plastic of plant organs, retain several features that are otherwise seen only in the Engelhardieae. These similarities in leaf architecture between the fossil Platycarya species and Engelhardieae are advanced features for the Juglandaceae, and thus indicate a sister-group relationship between the two lines. In contrast to the leaves, the fruits, inflorescences, and pollen of the fossil Platycarya species are almost as specialized as those of the extant P. strobilacea and bear little resemblance to the same structures in other genera of the family. The morphology, taphonomy, sedimentary setting, and geographic and stratigraphic distribution of three of the fossil platycaryoid species suggest that they were wind-dispersed, early successional plants that grew in thickets. This habit is retained by Platycarya strobilacea and is typical of many of the amentiferae (e.g. Myricaceae, Betulaceae). The r-selected life-history pattern of the Platycarya line may well have contributed to its low diversity through geologic time.

THE PLATYCARYA PERPLEX AND THE EVOLUTION OF THE JUGLANDACEAE

We report on the leaves, fruits, inflorescences, and pollen of two fossil species in the genus Platycarya. The association of these dispersed organs has been established by their repeated co‐occurrence at a large number of localities, and for two of the organs (fruit and pistillate inflorescence, and pollen and staminate inflorescence) by apparent organic attachment of compression fossils. Each of the two species can be distinguished by characteristics of all the known megafossil organs. We also review the fossil record of dispersed platycaryoid fruits and inflorescences, recognizing three additional species of Platycarya and two of Hooleya. Two of the fossil Platycarya species are morphologically very different from the living Platycarya strobilacea Sieb. et Zucc., but they show the diagnostic features of the genus. Hooleya is a generalized member of the Platycaryeae that is probably close to the ancestry of Platycarya.The two Platycarya species known from multiple organs provide a remarkable example of mosaic evolution in which fertile and foliar structures have attained different levels of morphological specialization. The leaves, often considered the most plastic of plant organs, retain several features that are otherwise seen only in the Engelhardieae. These similarities in leaf architecture between the fossil Platycarya species and Engelhardieae are advanced features for the Juglandaceae, and thus indicate a sister‐group relationship between the two lines. In contrast to the leaves, the fruits, inflorescences, and pollen of the fossil Platycarya species are almost as specialized as those of the extant P. strobilacea and bear little resemblance to the same structures in other genera of the family.The morphology, taphonomy, sedimentary setting, and geographic and stratigraphic distribution of three of the fossil platycaryoid species suggest that they were wind‐dispersed, early successional plants that grew in thickets. This habit is retained by Platycarya strobilacea and is typical of many of the amentiferae (e.g. Myricaceae, Betulaceae). The r‐selected life‐history pattern of the Platycarya line may well have contributed to its low diversity through geologic time.