bluuebunny/crossref_metadata_2025 huggingface dataset:
HETEROPHYLLY AND NEOFORMATION OF LEAVES IN SUGAR MAPLE (ACER SACCHARUM)
Authors: Steingraeber David A.
Published: January 2018

Variation in leaf form and timing of leaf initiation were investigated in vigorous leader shoots of open‐grown saplings and larger forest trees of sugar maple (Acer saccharum Marsh.). Winter buds of leader shoots usually contained 6 or 8 leaf primordia and embryonic leaves, whereas 12 to 18 leaves typically expanded along the shoots each year. Preformed (early) leaves differ in form from neoformed (late) leaves. As in some other Acer species, the first‐formed late leaves have large angles of secondary lobe divergence and deeply indented sinuses. This pattern of heterophylly contributes to the multilayered nature of open‐grown saplings and leader shoots of forest trees of sugar maple.
SMITHSONIELLA GEN. NOV., A POSSIBLE EVOLUTIONARY LINK BETWEEN THE MULTICELLULAR AND SIPHONOUS HABITS IN THE ULVOPHYCEAE, CHLOROPHYTA
Authors: Sears James R. , Brawley Susan H.
Published: January 2018

A low relief, green turf‐forming alga of a heterotrichous habit was discovered in the coral reef microcosm, Museum of Natural History, Smithsonian Institution. Erect filaments bore lateral, specialized sporangia and together with basal filaments possessed septal plugs between adjacent cells, grossly similar to the “pit connections” of red algae.

Data are presented which: 1) establish the identity of our plant with a plant recently described asPilinia earleaeGallagheretHumm from the Florida Gulf coast; 2) support our establishment of the new genusSmithsoniellaand our transfer ofP. earleaeto this new taxon.

Additional data on pigmentation and cytology are related to the fine structure of other selected green algae to develop and test three hypotheses, viz.Smithsoniella earleaerepresents either: 1) a symbiotic association between a green and a red alga; 2) an alga which belongs to either theUlotrichales, Chaetophoralesor theChroolepidales; or 3) an alga representing an evolutionary link between filamentous forms of the Ulvophyceae and members of the coenocytic siphonalean complex (e.g., Codiales or Caulerpales) of the Chlorophyta. Data refute hypotheses 1 and 2 but do lend support to the third hypothesis.
STRUCTURALLY PRESERVED PLANTS FROM SOUTHEASTERN KENTUCKY: STAUROPTERIS BISERIATA SP. NOV.
Authors: Ochan Michael A. , Taylor Thomas N.
Published: January 2018

Several axes of the coenopterid fern Stauropteris are described from permineralized peat associated with Lower‐Middle Pennsylvanian coal deposits of southeastern Kentucky. This represents the first documented report of the genus in North America. The specimens are regarded as representatives of a new species—S. biseriata—based on the distinctive branching habit. Three branch orders are described, and in each case, branches are singular and distichous, arranged in a two‐ranked pattern. This is in contrast to other species of Stauropteris in which the branches are paired and form a quadriseriate pattern. A pair of vascularized aphlebiae subtend each branch through all branching orders. Aphlebiae associated with first‐ and second‐order branches are three‐parted at the point of insertion; those that subtend third‐order branches are singular. Stauropteris and a number of Devonian fern‐like plants are compared on the basis of certain morphological similarities.
THE ANATOMY OF THE PISTILLATE INFLORESCENCE AND FLOWER OF CASUARINA VERTICILLATA LAMARCK (CASUARINACEAE)
Authors: Flores Eugenia M. , Moseley Maynard F.
Published: January 2018

The pistillate inflorescence of Casuarina verticillata is described as consisting of a primary axis bearing whorls of bracts with a cymule in the axil of each bract of the more central whorls. Each cymule consists of an atepallate, two‐carpellate, syncarpous floret and two, lateral, once‐lobed bracteoles. A “peripheral intercalary” meristem, in which divisions are primarily periclinal, forms a meshwork beneath the bracts from early development and moves the connate bracts centrifugally around the cymules and extends and binds the bracts, and to some extent the bracteoles, of the fertile part of the inflorescence together. Each bract receives a single trace; each cymule receives two traces. Each bundle extension of a cymule trace supplies: 1) a branch which joins its counterpart to become the anterior common carpellary bundle; 2) a second branch which joins its counterpart to become the posterior common carpellary bundle; and 3) a central branch which supplies a lateral bracteole. Within each floret, each common carpellary bundle provides a dorsal carpellary bundle, two ventral carpellary bundles (fertile anterior carpel) or one common ventral bundle (sterile posterior carpel). The ventral bundle‐supplies join and form a single placental bundle which lies in the gynoecial septum, and which, in turn, supplies the two ovules in the anterior carpel. Whether the inflorescence is a simple racemose or a condensed cymose type cannot be determined from this species alone. The function of the sclerenchymatous, enclosing bracteoles and connate bracts is discussed.
COMPARATIVE POLLEN MORPHOLOGY OF THE AMERICAN MYRISTICACEOUS GENERA OTOBA, IRYANTHERA, AND OSTEOPHLOEUM
Authors: Walker James W. , Walker Audrey G.
Published: January 2018

Pollen of the American myristicaceous genera Otoba, Iryanthera, and Osteophloeum was studied with light, scanning electron, and transmission electron microscopy. Formal generic pollen descriptions are provided for each genus, all three of which possess distinctive pollen that is most readily distinguished by characters of exine structure and sculpturing. Pollen of Otoba has a basically granular interstitium with pendent granules attached to the inner face of the basically imperforate tectum and an unique patch of well‐developed columellae and a semitectate reticulum on its presumed proximal face. The somewhat similar, distinctly columellate, tectate‐perforate to semitectate pollen of Iryanthera and Osteophloeum may be distinguished by a reticulum that is beadlike in the former and psilate in the latter. Pollen of Iryanthera is more or less indistinguishable from that of the previously studied African myristicaceous genus Coelocaryon.
BREEDING SYSTEMS AND FECUNDITY IN THE AMERICAN GINSENG, PANAX QUINQUEFOLIUM (ARALIACEAE)
Authors: Lewis Walter H. , Zenger Vincent E.
Published: January 2018

American ginseng is self‐compatible with fecundity among bagged inflorescences equivalent to (Missouri) or greater (New York) than that observed for nonbagged inflorescences. Population differences in flowering time and synchrony, protandry, autogamy, xenogamy, and fecundity, imply major genetic divergence in the species.
EFFECTS OF SUGARS ON α‐AMYLASE ACTIVITY IN PEA EMBRYONIC AXES
Authors: Davis Bill D.
Published: January 2018

Several methods were used to test the hypothesis that α‐amylase activity in pea stem tissues is regulated by catabolite repression. The presence of various exogenous sucrose concentrations had little effect upon the accumulation and subsequent loss of enzyme activity in excised embryonic axes. Comparable results were observed for glucose, fructose, and maltose, and mixtures of sucrose and glucose. While growth and sugar accumulation was increased by culturing the axes in liquid medium, the activity was not reduced. Therefore the results of each procedure were inconsistent with the initial hypothesis. Preliminary experiments also demonstrated the lack of influence of sugars upon the in vitro activity of pea α‐amylase.
CHROMOSOME NUMBERS IN THE GENUS ANTHURIUM (ARACEAE) II
Authors: Sheffer Richard D. , Croat Thomas B.
Published: January 2018

Chromosome numbers were determined for 86 Anthurium species. Fifty‐one of these were newly determined with counts ranging from 2n = 24 to 66 and 30 being the most common. All known Anthurium chromosome numbers were summarized, and 43 taxonomic changes were made in the previous reports to reflect current taxonomy. In terms of somatic chromosome numbers, the numbers form four polyploid series of 20–40–60, 24–30–48–84, 28–56 and 30–60–90–ca. 124. Paleoaneuploidy, polyploidy and B‐chromosomes are basic features of the genus, but subsequent recent aneuploidy is not. The exact nature of chromosome evolution in Anthurium remains to be elucidated.
THE NACREOUS WALLS OF SIEVE ELEMENTS IN SEAGRASSES
Authors: Kuo John
Published: January 2018

The nacreous walls of sieve elements occur in seagrasses in all three genera of the family Zosteraceae and the genus Halodule of the family Cymodoceaceae but are absent from another eight seagrass genera belonging to the families Hydrocharitaceae, Cymodoceaceae, and Posidoniaceae. They occur in leaf blades, leaf sheaths, rhizomes, and erect stems but are not present in root tissues. The nacreous wall is uneven along the inner limits reflecting irregular thickness. The wall consists of hemicellulose or pectin and cellulose, but no protein, lignin, or lipid. Ultrastructurally, the wall contains parallel microfibrils or loose fibrils embedded in an amorphous matrix. Open pores occur in sieve plates and branching plasmodesmata are present in enlarged sieve areas. Mitochondria, endoplasmic reticulum, and plastids are also present in these sieve elements.
FLORAL ORGANOGENESIS IN FIVE GENERA OF THE MARANTACEAE AND IN CANNA (CANNACEAE)
Authors: Kirchoff Bruce K.
Published: January 2018

The paired flowers of all species of the Marantaceae studied, except Monotagma plurispicatum, are produced through the division of an apical meristem with a tunica‐corpus structure. The solitary flowers of M. plurispicatum develop from a similar meristem which does not bifurcate. The paired flowers of Canna indica are produced in the axil of a florescence bract through the formation of a bract and an axillary flower on the side of the primordium which gives rise to the largest flower of the pair. The sequence of organ initiation for both families is: calyx, corolla and inner androecial whorl, outer androecial whorl, gynoecium. The sequence of sepal formation is opposite in the two families. In the Cannaceae it leads directly into the spiral created by the formation of the other organs, while in the Marantaceae the sequence of sepal formation follows a spiral opposite to that of the other floral organs. The members of the corolla and inner androecial whorl separate from common primordia. In general these common primordia separate into a petal and an inner androecial member through the initiation of two growth centers, at the same level, in the dorsal and ventral flanks of the primordium. In Ischnosiphon elegans and Pleiostachya pruinosa the stamen is initiated at a lower position than the petal in the ventral flank of the common primordium. A similar pattern of initiation is described for the callose staminode in Marantochloa purpurea and Canna indica. This pattern is interpreted as a variation on the more generalized pattern of inner androecial formation found in the other genera.
STRUCTURE AND DEVELOPMENT OF WALLS IN FUNARIA STOMATA
Authors: Sack Fred , Paolillo D. J.
Published: January 2018

The development and structure of the guard cell walls ofFunaria hygrometricaHedw. (Musci) were studied with the light and electron microscopes. The stoma consists of only one, binucleate guard cell as the pore wall does not extend to the ends of the cell. The guard cell wall is thinnest in the dorsal wall near the outer wall but during movement is most likely to flex at thin areas of the outer and ventral walls. The mature wall contains a mottled layer sandwiched between two, more fibrillar layers. The internal wall layer has sublayers with fibrils in axial and radial orientations with respect to the pore. During substomatal cavity formation, the middle lamella is stretched into an electron dense network and into strands and sheets. After stomatal pore formation, the subsidiary cell walls close to the guard cell become strikingly thickened. The functional implications of these results are discussed.
WIND DISPERSAL OF FRUITS WITH VARIABLE SEED NUMBER IN A TROPICAL TREE (LONCHOCARPUS PENTAPHYLLUS: LEGUMINOSAE)
Authors: Augspurger Carol K. , Hogan Kevin P.
Published: January 2018

The tropical tree, Lonchocarpus pentaphyllus (Poir.) DC. (Leguminosae‐Papilionoideae), matures indehiscent wind‐dispersed fruits containing 0–4 seeds. Most fruits are one‐seeded (82%) while less than 2% are three‐seeded. An increase in seed number per fruit correlates with increases in four characteristics expected to affect dispersal distance under field conditions: fruit weight, fruit area, square root of wing‐loading, and rate of descent in still air. The dry weight of a seed decreases with an increase in seed number per fruit. Under field conditions nearly 40% of the mature fruits fall within the radius of the tree crown. Fruits with more intact seeds are dispersed shorter distances; fruits with no developed seeds travel the farthest. Among one‐seeded fruits dispersed beyond the crown radius, dispersal distance is inversely proportional to the square root of wing‐loading. The weight of seed in these one‐seeded fruits, however, is independent of dispersal distance. Fruits with more seeds have a higher proportion of underdeveloped seeds. However, a greater proportion of two‐ and three‐seeded fruits have at least one intact mature seed than do one‐seeded fruits. This comparative study illustrates that changes in fruit morphology and weight associated with different numbers of seeds per fruit affect dispersal properties as well. A decrease in seed number per fruit increases both seed weight and dispersal distance, but it decreases the probability that a given dispersal event results in movement of an intact seed.
COMPARATIVE FLOWER DEVELOPMENT IN THE CLEISTOGAMOUS SPECIES VIOLA ODORATA. I. A GROWTH RATE STUDY
Authors: Mayers Anna M. , Lord Elizabeth M.
Published: January 2018

In Viola odorata, chasmogamous (CH) or open flowers and small, short‐petioled leaves are produced under 11 hr or less of daylight, cleistogamous (CL) or closed flowers and large, long‐petioled leaves under 14 hr or more of daylight, and intermediate floral and leaf forms under transitional photoperiods. CL flowers are approximately four times smaller than CH flowers and differ morphologically in repressed growth of the anterior petal spur and staminal nectaries, and recurving of the style which remains enclosed within the cone formed by anther appendages. Both CH and CL shoot systems conform to a (2 + 3) phyllotaxis with minor differences in leaf divergence angles and phyllotactic indices. The larger CL leaf grows significantly faster than the CH leaf, and an increased rate of leaf initiation occurs in the CL apex represented by a plastochron of 3.4 days compared to 4.3 days in the CH apex. The plastochron index was used to indirectly age young floral primordia nondestructively until prophase of meiosis I within the anthers. This event occurs 8 days earlier in the CL than the CH flower. Time from meiosis until flower maturity, determined by direct observation, is about 14 days for the CL flower, versus 21 days for the CH flower.
EXPERIMENTAL ECOLOGICAL GENETICS IN PLANTAGO IX. DIFFERENCES IN GROWTH AND VEGETATIVE REPRODUCTION IN PLANTAGO LANCEOLATA L. (PLANTAGINACEAE) FROM ADJACENT HABITATS
Authors: Teramura Alan H.
Published: January 2018

Two adjacent populations of P. lanceolata were observed to have different rosette morphologies and apparently, capacities for vegetative reproduction. Plants growing in an open, sunny habitat were clumped while those found growing in a periodically shaded habitat, only developed as single rosettes. Representative genotypes from each population were cloned from leaf cuttings and propagated in controlled‐environment facilities. Growth and vegetative reproduction were measured under two contrasting irradiances to determine whether the differences seen in the field were primarily genetic or environmentally induced. These studies indicated that each population was adapted to the light regime most similar to that prevailing in its natural habitat. The clumping in the open population was the result of a greater capacity for vegetative reproduction.
COMPARISON OF INTRASPECIFIC VARIATIONS IN THE REPRODUCTION AND PHOTOSYNTHESIS OF AN UNDERSTORY HERB, ARNICA CORDIFOLIA
Authors: Young Donald R.
Published: January 2018

Intraspecific variations in the reproduction of individual ramets and monospecific patches of the understory herb Arnica cordifolia Hook. were compared with variations in photosynthesis and understory light conditions. Ramets and patches were compared from three microhabitats (open, intermediate, and shaded) that differed in daily integrated irradiance. Individual ramets from open microhabitats (> 12 MJ m−2 d−1) had 23% more total dry wt and produced twice as many seeds, when compared to ramets from shaded locations (< 5 MJ m−2 d−1). In addition, monospecific patches from open locations were 63% more dense, and estimates of seed and vegetative patch reproductive effort were 4 and 2 times greater, respectively, when compared to shaded plant patches. For all measurements, ramets and patches from intermediate understory locations (6–10 MJ m−2 d−1) were intermediate in reproductive capacity between those of open and shaded locations. In addition, A. cordifolia seeds from open microhabitats germinated significantly better (45%) than either intermediate or shaded location seeds under high light and only seeds from shaded microhabitats germinated (14%) in the dark. Compared to shaded location plants, the greater total dry weight and seed production of individual ramets and the greater estimated reproductive effort of patches from open locations corresponded to a greater maximum photosynthetic rate (16.9 μmoles m−2 s−1) and daily carbon gain (12.2 g m−2 d−1). Possibly, a greater photosynthetic capacity may make more photosynthetic resources available for reproduction by A. cordifolia plants in open locations. Thus, intraspecific variation in physiology may contribute to intraspecific variation in reproduction.
STRUCTURE AND AFFINITIES OF ATHROTAXITES BERRYI BELL, AN EARLY CRETACEOUS CONIFER
Authors: Miller Charles N. , LaPasha Constantine A.
Published: January 2018

Compressions and impressions of leafy twigs, pollen cones, and seed cones of Athrotaxites berryi are abundant in certain layers of the Kootenai Formation (Aptian) in Montana and the Lower Blairmore Formation in adjacent Alberta. The twigs are densely covered by helically arranged leaves that are about 2 mm long and wide. Pollen cones are borne laterally on ultimate branch segments. Some are sessile, while others terminate a minute lateral branch. The cones are 3–4 mm in diam and about 10 mm long. Each sporophyll has a stalk that is about 0.7 mm long and an upturned laminar tip that is 1–1.5 mm long by 1 mm wide. At least two pollen sacs are attached to the abaxial side of each sporophyll. Seed cones are borne terminally on lateral branches that are often curved. These cones are about 10 mm at their widest diameter and about 15 mm long. Each bract and associated ovuliferous scale are fused to form a wedge‐shaped complex that is 4–5 mm long. The complex is 0.7 mm wide at its base and expands to about 2.5 mm wide and thick near its apex. The tip of the complex narrows abruptly to a point and terminates in a spine that is about 0.5 mm long. At least one seed occurs on the adaxial side of each complex. Athrotaxites berryi belongs to the Taxodiaceae. It resembles modern Athrotaxis cupressoides but differs from it in too many aspects to be included in the modern genus.
COMPETITIVE SUBORDINATION OF A PIEDMONT OLD FIELD SUCCESSIONAL DOMINANT BY AN INTRODUCED SPECIES
Authors: Tremmel David C. , Peterson K. M.
Published: January 2018

Heterotheca latifolia Buckley has been replacing Erigeron canadensis L. as the first year dominant in Carolina‐Georgia piedmont old field succession. This species of Heterotheca was introduced to this area in the 1940's. Both the Heterotheca and Erigeron species are winter annuals. We used a replacement series experiment to detect competition (interference) under a variety of greenhouse environments to seek a possible explanation for the observed changes in old field succession. Interspecific competition between Heterotheca and Erigeron plants resulted in significant reductions in the dry weight of Erigeron plants. Erigeron wilted before Heterotheca in 98.2% of observations of first‐wilting in mixed‐species cultures. At flowering, Erigeron plants in mixed‐species cultures were shorter than Heterotheca plants. Poor seed dispersal in mixed‐species communities in the field could limit Erigeron's ability to populate new areas. Greenhouse flats densely sown with equal numbers of seeds of both species resulted in a winter rosette cover of Heterotheca only. Heterotheca's assumption of the role of first year dominant in old field succession may be due to interspecific competition with Erigeron at all stages in its life cycle. These competitive effects can be observed under a variety of environmental conditions, especially those in which drought occurs.
DEVELOPMENTAL POTENTIAL OF EXCISED PRIMORDIAL AND EXPANDING LEAVES OF COLEUS BLUMEI BENTH.
Authors: Smith Roberta H.
Published: January 2018

Coleus blumei Benth. primordial leaves 1 through 4 and expanding leaves 5 to 8 were isolated and cultured to examine the effects of auxin and kinetin on development. Without the plant growth regulators in the medium, expanding leaves 7 and 8 developed as leaves; younger leaf primordia did not develop. With 0.01 to 5.0 mg/1 IAA, 2–7% of the youngest pair of primordial leaves (1 and 2) developed as roots. Small leaf blade development occurred on IAA at 0.5 to 5.0 mg/1 with 10–12% of the explants, and shoots developed from 2% of the youngest primordia explants at 3 mg/1 IAA. With 2–28% of the second set of primordial leaves (3 and 4), a leaf with a root developed with 0.01 to 5.0 mg/1 IAA. At 3.0 mg/1 IAA, in addition to leaf formation, 2% of the explants formed a rosette of leaves and 1% formed a shoot. With the highest level of IAA (5 mg/1), 2% of the explants formed a root. Expanding leaves 5 through 8 developed mostly into leaves without petioles on IAA and kinetin. Plant development occurred from 2% of the youngest primordial leaves on 0.03 mg/1 kinetin; otherwise, these primordia on 0.003 to 2 mg/1 kinetin developed into abnormal leaves. Primordia 3 and 4 developed into normal appearing leaves at levels of kinetin between 0.03 and 2 mg/1. At lower levels the leaves were abnormal.
THE IMPACT OF THE OLYMPIC MARMOT ON SUBALPINE VEGETATION STRUCTURE
Authors: del Moral Roger
Published: January 2018

The impact of Olympic marmots on subalpine meadow vegetation was examined by descriptive methods. Differential grazing and various earth moving activities of marmots produce marked vegetational contrasts between mound vegetation and the surrounding meadows, between heavily impacted and lightly impacted vegetation immediately surrounding mounds, and between vegetation in the central portion of a colony and that on its periphery. The patterns differed in degree between a dry meadow with lower production and a wet meadow with higher production. In dry meadows, marmots forage over greater distances and their impacts are less concentrated near mounds. In wet meadows, impacts are intense near mounds. Differences were documented in structural features such as species richness, equitability, and percent vegetation cover and in shifts of species composition. As marmot impact increased, graminoid species declined somewhat, palatable species declined markedly, and both ruderal and unpalatable species increased greatly. Moderate marmot activity reduced the dominance of common species and thereby enhanced community diversity. These observations emphasize that much of the natural landscape, seemingly in harmonious equilibrium with its physical environment, is strongly molded by the activities of native animals.
A CONTRIBUTION TO THE POPULATION BIOLOGY OF OENOTHERA GRANDIFLORA L'HER.
Authors: Steiner Erich , Stubbe Wilfried
Published: January 2018

The cytogenetic characteristics of samples from 12 populations of Oe. grandiflora L'Her. were investigated. The combination of characters which distinguishes Oe. grandiflora from its sympatric relative, Oe. biennis, includes deeply scalloped margins of the rosette leaf bases, red flecks on the young leaves, clear green stem tips with erect or semi‐erect hairs, and clusters of lateral branches at the tip of the central shoot or primary basal branches. In general, flowering is in response to short days and occurs from early August until late October. The species, originally believed to be indigenous to southern Alabama, is found throughout the Southeast, but its pre‐settlement distribution remains uncertain. Populations of Oe. grandiflora consist largely of structural homozygotes or forms showing small circles of chromosomes at meiosis, although one plant with a circle of ten and two pairs was observed. Five different chromosomal end arrangements have been identified; none of these differ, however, by more than two interchanges. The arrangement considered ancestral for the subsection Euoenothera is found in nine of the populations. The species is composed of both self‐incompatible as well as self‐compatible forms. Incompatibility alleles have been found in 7 of the 12 populations analyzed.
THE MICRO‐OPTICS OF LEAVES. I. PATTERNS OF REFLECTION FROM THE EPIDERMIS
Authors: McClendon John H.
Published: January 2018

Low‐magnification photographs of glabrous upper surfaces using white light show that no matter whether the visual appearance is shiny or matte, the outer cuticles are specularly reflective. In all cases, the individual epidermal cells are seen as bright spots of reflected light, due to their convex outer surfaces. This shows that at least some of the apparently diffuse reflection from leaves is specularly reflected from the outer surface. Quantitative data were obtained for both upper and lower surfaces of a variety of leaves, using light of 632.8 nm incident at 60° from the normal. Light departing the leaf was detected in two directions: normal to the leaf (“diffuse”), and at 60° (“specular”), and compared with the reflection from a standard white block. By this criterion, some leaves were quite shiny, confirming the visual impression, but others were not. In only two cases did the “diffuse” reflection exceed the “specular” (as would be expected from a true diffuse reflector); these were leaves with thick coatings of hairs. Less than 10% of the incident light is reflected by the cuticle of a glabrous leaf.
AXIAL ROTATION OF ERYTHRINA HERBACEA LEAFLETS
Authors: Herbert Thomas J.
Published: January 2018

The leaflets of Erythrina herbacea, a leguminous plant native to subtropical North America, undergo daily movements. During the night, leaflets are oriented with their tips pointing downwards and show no rotation around the midrib of each leaflet. In the morning, leaflets rise, passing through a horizontal orientation and, somewhat before noon, reach a maximum average midrib elevation of approximately sixty degrees above the horizontal plane. Simultaneously, each leaflet rotates about the midrib by an average angle of forty to fifty degrees. These leaflet movements result in an initial increase in the relative leaflet surface area presented to the sun during the morning, a decrease in interception of direct solar radiation around noon, followed by a second maximum in light interception in early afternoon.
ANATOMY OF NODES VS. INTERNODES IN COLEUS: THE LONGITUDINAL COURSE OF XYLEM DIFFERENTIATION
Authors: Bruck David K. , Paolillo Dominick J.
Published: January 2018

All xylem strands in Coleus are initiated and differentiated discontinuously and bidirectionally from each nodal region along the lengths of the strands. Within nodes, the strands are larger in transsectional area and contain a greater number of vessels, a greater proportion of vessel elements vs. xylary parenchyma cells, and vessels in more advanced stages of differentiation than in adjacent internodes. When xylem develops in bundles that initially are composed only of phloem, or in short, isolated strands, it is initiated within nodal regions. The increased xylogenesis in the nodal regions is suggestive of locally enhanced auxin levels. Experiments were conducted to determine whether the advanced state of nodal vessel differentiation is a function of auxin import to the node from the leaf pair inserted at that node or whether it is due to an effect in the node of auxin transport from another (distal) source. A combined result was indicated, as removal of a leaf pair led to a decline in nodal xylem differentiation in the side bundles but not the corner traces passing through the node from younger leaves. The effect of a leaf pair on side bundle xylem differentiation at the same node was replaceable by exogenous IAA application to the cut leaf sites.
RELATIONSHIPS AMONG REPRODUCTION, GROWTH RATES, AND PROTEIN HETEROZYGOSITY IN PONDEROSA PINE
Authors: Linhart Yan B. , Mitton Jeffry B.
Published: January 2018

This report summarizes a 6‐yr study of male and female cone production in a population of 216 ponderosa pines whose ages, diameters, and genotypes at 7 protein polymorphisms are known. There are different schedules of male and female reproduction. The majority of cones are produced by the same few trees each year. There is a tradeoff between growth rate and female cone production but not pollen production. Differential female (but not male) cone production is associated with protein genotype. The variance of female reproductive effort declines with increasing protein heterozygosity.
STUDIES ON THE LEAF OF POPULUS DELTOIDES (SALICACEAE): QUANTITATIVE ASPECTS, AND SOLUTE CONCENTRATIONS OF THE SIEVE‐TUBE MEMBERS
Authors: Russin William A. , Evert Ray F.
Published: January 2018

The vascular system of the leaf of Populus deltoides Bartr. ex Marsh, was examined quantitatively, and plasmolytic studies were carried out to determine the solute concentrations of sieve‐tube members at various locations in the leaf. Both the total number and total crosssectional area of each cell type decreases with decreasing vein size. Although the proportion of phloem occupied by sieve tubes varies considerably from location to location, a linear relationship exists between cross‐sectional area of the vascular bundles and both total and mean cross‐sectional area of sieve tubes. Collectively, the cross‐sectional area of all tertiary and minor veins feeding into a secondary exceeds the total cross‐sectional area of sieve tubes at the base of that secondary. Moreover, the total volume of sieve tubes in the “catchment area” of a secondary vein is much greater than the total sieve tube volume of the secondary itself. Both tracheary elements and sieve‐tube members undergo a reduction in both total and mean crosssectional area in the constricted zone at the base of the leaf. The plasmolytic studies revealed the presence of positive concentration gradients in sieve tubes of the lamina from the minor veins and tips of the secondaries to the bases of the secondaries and their associated subjacent midvein bundles and from the upper to lower portions of the median bundle of the midvein.
DNA, RNA, AND PROTEIN COMPARISONS BETWEEN NODULATED AND NON‐NODULATED MALE‐STERILE AND MALE‐FERTILE GENOTYPES OF SOYBEAN (GLYCINE MAX L.)
Authors: Artis Deogratis E. , Miksche Jerome P. , Dhillon Sukhraj S.
Published: January 2018

Four soybean (Glycine max L. Merr.) lines isogenic except for loci controlling male sterility (ms1) and nodulation (rj1) were developed to study the effects of reproductive development and nitrogen source on the nucleic acid and protein levels within the leaves. Changes in DNA, RNA, protein, and cellular viability were measured from flowering (77 days after emergence) until maturity (147 days after emergence) in leaves of nodulated and non‐nodulated male‐sterile and fertile soybean genotypes. Leaf nuclei from the sterile genotypes yielded DNA amounts that were significantly higher than those from the fertile lines. The average DNA values for the nodulated sterile and nodulated fertile lines at 147 days after emergence were 7.01 and 2.45 picograms, respectively. The average 2C DNA amount as determined from dividing root‐tip nuclei was 2.83 picograms, which indicated occurrence of endopolyploid mechanisms in the sterile lines and age‐related loss of DNA in fertile lines. Similar to DNA findings, the RNA and protein values in the sterile lines were significantly higher than those values observed in the fertile lines, suggesting an increased capacity to synthesize protein. The soybean leaf nuclear DNA declined, especially in the fertile lines in terms of the percent endopolyploid nuclei as well as the average DNA content during maturation. The DNA decline in leaves of fertile genotypes suggests that the leaves may be exporting nucleosides and phosphates to the seeds during embryo formation. In the sterile lines, due to the reduced pod‐set, these ready reserves of nucleosides and phosphates tended to accumulate in the chromatin of the leaf nucleus as manifested by the DNA specific Feulgen stain.

By the end of the study (147 days after emergence), the nodulated fertile genotypes had experienced a dramatic loss in DNA, RNA, and protein. The nodulated sterile genotypes, however, indicated 65% more DNA, 59% more RNA, and 53% more protein as compared to the nodulated fertile genotypes at 147 days after emergence. The sterile lines also indicated the slowest increase in the death of cells, while the fertile lines indicated the fastest increase in nonviable cells, as shown by trypan blue staining. The fertile lines displayed normal monocarpic senescence throughout the study. The reproductive structures of fertile plants utilized the molecules in seed production, whereas in the sterile lines, these accumulated in leaf cells.
A MORPHOMETRIC ANALYSIS OF CELLULAR DIFFERENTIATION IN CAPS OF PRIMARY AND LATERAL ROOTS OF HELIANTHUS ANNUUS
Authors: Moore Randy
Published: January 2018

In order to determine if patterns of cell differentiation are similar in primary and lateral roots, I performed a morphometric analysis of the ultrastructure of calyptrogen, columella, and peripheral cells in primary and lateral roots of Helianthus annuus. Each cell type is characterized by a unique ultrastructure, and the ultrastructural changes characteristic of cellular differentiation in root caps are organelle specific. No major structural differences exist in the structures of the composite cell types, or in patterns of cell differentiation in caps of primary vs. lateral roots.
A MICROSCOPICAL STUDY OF THE STATOCYTE SYSTEM IN STEMS OF ETIOLATED PHASEOLUS SEEDLINGS
Authors: Verbelen Jean‐Pierre , Spruyt Eric , De Greef Jan A.
Published: January 2018

In etiolated bean seedlings there is a starch sheath around the vascular stem tissue. This cell layer shows a gradient of amyloplast number and cell dimensions. We demonstrated a maximum relative amyloplast pressure in the stem hook. Cytological as well as physiological arguments indicate that the stem hook may play an important role in graviperception through this starch sheath.
MITOTIC INSTABILITY IN HAPLOPAPPUS: STRUCTURAL AND GENIC CAUSES
Authors: Jackson R. C.
Published: January 2018

Mitotic instability was found in an intraspecific hybrid of Haplopappus gracilis (Nutt.) Gray and in an interspecific hybrid of H. arenarius Benth. and H. aureus Gray. The latter cross was between distantly related species with different chromosome numbers and amounts of DNA. The intraspecific hybrid exhibited a partly recessive phenotype due to loss of a chromosome segment containing the wild type locus, and the interspecific hybrid showed abnormal developmental patterns for several morphological characters due to chromatin loss. Both hybrids were slower growing, smaller, and generally weaker than parental types. In both examples, this weakness was correlated with chromatin loss due to cleavage by cell wall formation across chromosome arms too long to separate properly at anaphase. This was caused by a very unequal translocation in H. gracilis and to a disparity in genome sizes in the interspecific hybrid. In both examples, the initial chromosome cleavage resulted in a breakage‐fusion‐bridge cycle that persisted into some BC, progeny of H. gracilis.
MEGASPOROGENESIS AND MEGAGAMETOGENESIS IN SOYBEAN, GLYCINE MAX
Authors: Kennell John C. , Horner Harry T.
Published: January 2018

Megasporogenesis and megagametogenesis were examined in Glycine max with light, fluorescence, and electron microscopy. Megasporogenesis results in a linear tetrad of four megaspores. Megagametophyte development is of the Polygonum type, with the functional chalazal megaspore undergoing three successive mitotic divisions to produce an eight‐nucleate, seven‐celled mature megagametophyte. The central cell becomes packed with starch. At fertilization, the antipodals are degenerate, the polar nuclei have fused, starch is diminished, and the egg occupies most of the micropylar portion of the megagametophyte. Several pollen tubes were occasionally observed at each micropyle, yet only one was involved in fertilization. Pollen tube entry occurs through a slightly reduced, viable synergid cell. Endosperm development precedes embryo growth. These results describing normal development allow important comparison with genetic mutants of soybean that affect female fertility.
POLLEN SELECTION AND THE GAMETOPHYTIC EXPRESSION OF METAL TOLERANCE IN SILENE DIOICA (CARYOPHYLLACEAE) AND MIMULUS GUTTATUS (SCROPHULARIACEAE)
Authors: Searcy Karen B. , Mulcahy David L.
Published: January 2018

A selection experiment was undertaken to test if metal tolerance expressed in pollen was determined by the pollen genotype, and if selection for metal tolerance could be effective during pollen development in the anther. Heterozygous metal tolerant plants of Silene dioica and Mimulus guttatus were cloned and grown either in the absence or presence of toxic concentrations of zinc or copper. These metals entered the flowers in potentially toxic amounts. The percent viable pollen decreased when compared to control plants, and the remaining pollen had a different pattern of germination in the presence of metals. In addition, the proportion of tolerant progeny from test crosses to metal sensitive plants increased significantly if pollen came from treated clones. Thus, selection appeared to be effective during pollen development, and metal tolerance in pollen significantly influenced by the pollen genome.
REPRODUCTIVE MORPHOLOGY OF QUERCUS (FAGACEAE)
Authors: Kaul Robert B.
Published: January 2018

Details of inflorescence, floral, and fruit morphology have been studied in more than 120 species of Asiatic and American Quercus. Of the two subgenera, subgenus Cyclobalanopsis has fewer species but greater diversity of reproductive morphology than subgenus Quercus. Some character states of subgenus Cyclobalanopsis, such as more numerous stamens, male flowers sometimes grouped in dichasia, abortive ovules well developed, prominent intrusive septae in the nut, and lamellate cupules, are shared with Lithocarpus. The diversity of cupular sizes, coverage, and ornamentation raises questions about the adaptive nature, ecological function, and phylogeny of the cupule, which clearly has by now evolved as a structure with its own qualities.
EXTRAFLORAL NECTAR OF FEROCACTUS ACANTHODES (CACTACEAE): COMPOSITION AND ITS IMPORTANCE TO ANTS
Authors: Ruffner George A. , Clark W. Dennis
Published: January 2018

Ants are attracted to extrafloral nectaries subtending reproductive organs of Ferocactus acanthodes var. lecontei (Cactaceae) in central Arizona. Extrafloral nectar produced by these glands contained amino acids, sugars, and water. Nectar quality and composition varied temporally in relation to plant reproductive phenology. The number of nectar glands on a barrel cactus did not change significantly, however; the mass of nectar produced per gland increased significantly with immature fruit production. Of the three sugars present in extrafloral nectar (fructose, glucose, and sucrose), only glucose occurred at a higher concentration in June, when immature fruits first appeared on barrel cactus. Amino acid concentration and composition in extrafloral nectar of barrel cactus did not change significantly over time. Ant density on barrel cactus increased significantly from mid‐May to mid‐June at two field sites. Water availability per nectar gland increased 158% from May to June. Water plays an important role in attracting ants to barrel cacti.
FLAVONOIDS OF THE MENYANTHACEAE: INTRA‐ AND INTERFAMILIAL RELATIONSHIPS
Authors: Bohm Bruce A. , Nicholls K. W. , Ornduff Robert
Published: January 2018

This paper describes our study of the flavonoid chemistry of the Menyanthaceae, which included Menyanthes, Fauria (= Nephrophyllidium), Liparophyllum (all monotypic), nine species of Nymphoides, and 11 species of Villarsia. The flavonoid profiles are based upon kaempferol, 7‐O‐methylkaempferol, quercetin, 7‐O‐methylquercetin, isorhamnetin, 3,7‐di‐O‐methylquercetin, and 7,3′‐di‐O‐methylquercetin, although not all taxa exhibit all of these aglycones. These compounds occur as a complex mixture of 3‐O‐mono‐ and 3‐O‐diglycosides; 4′‐O‐glucosides were restricted to four species of Nymphoides. Some acylated glycosides were also observed. The presence of flavonols and absence of both C‐glycosylflavones and xanthones set the Menyanthaceae apart from the Gentianaceae, the family with which it is most often allied. Flavonoid data do not allow assignment of the Menyanthaceae with surety to either the Gentianales or Solanales. The flavonoid profiles of Liparophyllum and Fauria are unique within the family and do not support a close affinity of the latter genus to Menyanthes. A close relationship between Nymphoides and Villarsia, suggested on morphological grounds, is supported by the flavonoid data. Flavonoids support the view, based upon morphology, that the South African Villarsia capensis is more closely related to eastern Australian Villarsia species than to Western Australian ones that are geographically closer. Segregation of Nymphoides fallax from other Meso‐American and Caribbean taxa is supported by the flavonoid data. Flavonoid data also support the view that N. indica is a circumtropical taxon not deserving separate species status in the New World.
ALLOZYME DIVERGENCE AMONG FIVE DIPLOID SPECIES OF ANTENNARIA (ASTERACEAE: INULEAE) AND THEIR ALLOPOLYPLOID DERIVATIVES
Authors: Bayer Randall J. , Crawford Daniel J.
Published: January 2018

The Antennaria parlinii and A. neodioica agamic complexes are widely distributed across North America. Morphological data have suggested that these dioecious, perennial, entire‐leaved herbs are of multiple hybrid origin from among five sexual diploid species. Antennaria neglecta, A. plantaginifolia, A. racemosa, and A. virginica are hypothesized to be the diploid progenitors of the A. neodioica complex, whereas A. parlinii sensu lato is thought to include the genomes of A. plantaginifolia, A. racemosa, and A. solitaria. An electrophoretic study was initiated to assess the degree of divergence among the five diploid species and to test the hypotheses of the hybrid (allopolyploid) origins of A. parlinii and A. neodioica. Twenty genetic loci were surveyed in 76 populations of the diploid and polyploid taxa. The diploid species are well defined morphologically, although the genetic basis of differences distinguishing them have not been determined. The species exhibit little divergence at genes specifying soluble enzymes, however each species has unique alleles in highest frequency at one or two genes. Allozymes indicate that gene diversity in the obligately outcrossing diploids occurs primarily within rather than among populations. The shale barren endemic, A. virginica, is as genetically diverse as the more edaphically diverse and widespread species. Tetraploid cytotypes of diploid (2n = 28) A. virginica possess the same allozymes as the diploids and these cytotypes appear to be of autopolyploid (non‐hybrid) origin. Enzyme electrophoresis is concordant with morphological data in suggesting that A. neodioica contains the genomes of A. neglecta, A. virginica, A. plantaginifolia, A. racemosa and perhaps A. solitaria whereas the latter three species are the progenitors of A. parlinii.
PHLOEM ANATOMY IN STAUROPTERIS BISERIATA FROM THE PENNSYLVANIAN OF NORTH AMERICA
Authors: Smoot Edith L. , Wege Mary Vande
Published: January 2018

Phloem anatomy in the coenopterid fern Stauropteris biseriata is detailed from Lower‐Middle Pennsylvanian coal ball specimens from eastern Kentucky. Axes exhibit a cruciate‐shaped xylem trace in transverse section. Phloem tissue completely surrounds the xylem, but is more extensively developed in the embayments between the xylem arms. Phloem is composed of elongate conducting elements with a few scattered parenchyma cells. Large and small sieve cells are present, with larger ones occurring in the embayments within the primary plane of symmetry of the axes. Large elements are approximately twice the diameter of the smaller sieve elements. Oval sieve areas and pores have been observed on lateral and oblique end walls of both large and small elements. The structure and composition of Stauropteris phloem is discussed in relationship to the available information on phloem anatomy in other fossil cryptogams.
TEMPORAL AND SPATIAL PATTERNS OF SPECIFIC LEAF WEIGHT IN SUCCESSIONAL NORTHERN HARDWOOD TREE SPECIES
Authors: Jurik Thomas W.
Published: January 2018

Temporal and spatial patterns of specific leaf weight (SLW, g/m2) were determined for deciduous hardwood tree species in natural habitats in northern lower Michigan to evaluate the utility of SLW as an index of leaf photosynthetic capacity. No significant diurnal changes in SLW were found. Specific leaf weight decreased and then increased during leaf expansion in the spring. Most species, especially those located in the understory, then had relatively constant SLW for most of the growing season, followed by a decline in SLW during autumn. Specific leaf weight decreased exponentially down through the canopy with increasing cumulative leaf area index. Red oak (Quercus rubra), paper birch (Betula papyrifera), bigtooth aspen (Populus grandidentata), red maple (Acer rubrum), sugar maple (A. saccharum), and beech (Fagus grandifolia) generally had successively lower SLW, for leaves at any one level in the canopy. On a given site, comparisons between years and comparisons of leaves growing within 35 cm of each other showed that differences in SLW among species were not due solely to microenvironmental effects on SLW. Bigtooth aspen, red oak, and red maple on lower‐fertility sites had lower SLW than the same species on higher‐fertility sites. Maximum CO2 exchange rate, measured at light‐saturation in ambient CO2 and leaf temperatures of 20 to 25 C, increased with SLW. Photosynthetic capacities of species ranked by SLW in a shaded habitat suggest that red oak, red maple, sugar maple, and beech are successively better adapted to shady conditions.