bluuebunny/crossref_metadata_2025 huggingface dataset:
FLAVONOID RACES OF CLAYTONIA VIRGINICA (PORTULACACEAE)
Authors: Doyle Jeff J.
Published: January 2018

Four flavonoid races have been found in the Claytonia virginica aneuploid complex, differing from one another in the accumulation of 12 kaempferol and quercetin 3‐glycosides. Each of these races has a distinctive geographical distribution within the overall range of the species. The three major diploid cytotypes of C. virginica each belong to different races, two of which also include polyploids; a fourth race consists entirely of polyploids. An examination of biosynthetic pathways indicates that a small number of genetic changes are responsible for the observed variation; polyploidy per se does not appear to have contributed significantly to the production of novel compounds. Flavonoid data also suggest strongly that polyploidy within rather than between modern chemical races has been responsible for the bulk of chromosome number variation in the species.
MG2+, K+‐DEPENDENT PHOSPHATASE ACTIVITY DURING SEED DEVELOPMENT IN NICOTIANA TABACUM
Authors: Mogensen H. Lloyd , Pollak Peggy E.
Published: January 2018

Cation‐dependent phosphatase activity was followed in developing Nicotiana tabacum (tobacco) seeds from pre‐pollination to seed maturity. Enzyme activity increased rapidly up to 6 days post‐pollination, then dropped off until 13 days after pollination. At 15 days post‐pollination, enzyme activity had increased again, and at 17 days post‐pollination, it reached its highest level. At 19 days post‐pollination (seed maturity) enzyme activity was still 28% higher than that of the pre‐pollination stage. Since the two peaks in enzyme activity correlate very highly with endosperm growth (first peak) and embryo growth (second peak), it is suggested that the Mg2+, K+‐dependent phosphatase activity detected in this study is associated with the active transport of nutrients to the endosperm and embryo during seed development. The relatively high amount of enzyme activity remaining in the mature seed may represent a store of transport phosphatase that will be available for immediate use at the time of germination and early seedling growth.
DEVELOPMENTAL ANATOMY OF JUVENILE AND ADULT SHOOTS OF MARCGRAVIA RECTIFOLIA L
Authors: Dobbins David R. , Alden Harry , Marvel Debbie
Published: January 2018

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.
ULTRASTRUCTURE AND DEVELOPMENT OF THE MICROSPORANGIUM OF PSEUDOTSUGA MENZIESII (MIRB.) FRANCO. I. DORMANT STAGES
Authors: Singh Hardev , Owens John N. , Dietrich Hans F.
Published: January 2018

The dormant (mid‐November to mid‐February) microsporangia of Pseudotsuga menziesii (Douglas‐fir) contain pollen mother cells (PMC's) in diffuse diplotene, surrounded by 1–2 layers of tapetal cells and 3–4 layers of microsporangial wall cells. At the beginning of dormancy, PMC's are large and their walls are lysed. The cell walls contain a thick layer of loosely‐arranged fibrils which are produced in large vesicles in the PMC cytoplasm and are secreted across the plasma membrane. PMC's contain several layers of rough ER. The inner tangential and the radial walls of the tapetal cells are lysed. During dormancy the PMC's form many new autophagic vacuoles, the chromatin consists of a network of fine threads comprised of medium‐sized granules of uniform size and the nucleoli split. The outer tapetal wall is thick and becomes encrusted by an irregular lipid layer. The tapetal cytoplasm is similar to the PMC cytoplasm but is devoid of amyloplasts. The tapetal cytoplasm shows secretory activity at the beginning of dormancy and again near the end of dormancy. The later secretory activity results in the deposition of a spongy material, especially along the radial and inner walls of the tapetal cells. Tapetal cells contain 1–2 large nuclei which show prominent and irregular clumps of chromatin. Subcellular developmental changes occur in the dormant microsporangia of Pseudotsuga in much the same manner as has been reported for Pinus.
VASCULAR BUNDLES IN PETIOLES OF SOME HERBACEOUS AND WOODY DICOTYLEDONS
Authors: Maksymowych Andrew B. , Orkwiszewski Joseph A. J. , Maksymowych Roman
Published: January 2018

Structure and distribution of vascular bundles (VB) have been investigated in petioles of 26 herbaceous and woody dicotyledons. No single pattern of vascular bundle distribution could be found for both groups of plants. Both groups of plants had VB patterns ranging from a cylinder to separate bundles arranged in a variety of patterns, e.g., distorted cylinder, various configurations of a crescent, and other types. The total number of xylem vessels in herbaceous and woody plant petioles varied between 110 and 1756.
CHROMOSOME ANALYSIS OF HYBRIDS BETWEEN 4N GRINDELIA CAMPORUM AND 2N G. GRANDIFLORA (COMPOSITAE)
Authors: Dunford Max P.
Published: January 2018

Morphology and meiosis are described in four progeny plants resulting from tetraploid Grindelia camporum Greene (2n = 24) from California pollinated by diploid G. grandiflora Hook. (2n = 12) from Coahuila, Mexico. Three of the four progeny were tetraploid, morphologically like the pistillate parent, and had metaphase I chromosome configurations which included quadrivalents and a complementary number of bivalents. They are considered to have resulted from selfing. The fourth plant was triploid (2n = 18) andmorphologically intermediate between the parents. Chromosome configurations in the triploid were variable with univalents, ring and rod bivalents, trivalents and pentavalents. These two species are considered related through an ancestor with a basic genome, but are separated cytologically by polyploidy and by two distinct chromosomal interchanges that explain the configurations observed in the triploid hybrid.
TILOSOMES IN ROOTS OF ORCHIDACEAE: MORPHOLOGY AND SYSTEMATIC OCCURRENCE
Authors: Pridgeon Alec M. , Stern William Louis , Benzing David H.
Published: January 2018

Tilosomes, also called “fibrous bodies” or “rod bodies” in older literature, are lignified excrescences from the walls of cells of the innermost velamen cell layer adjacent to thin‐walled passage cells of the exodermis in roots of many epiphytic orchids. Seven broad morphological types are recognized: spongy, lamellate, discoid, webbed, meshed, baculate, and plaited. Some types characterize specific genera or subtribes of Orchidaceae. Of the 350 species in 175 genera included in a survey of the family, tilosomes occur in 95 species and 39 genera and are concentrated in tribe Polystachyeae and subtribes Sobraliinae, Coelogyninae, Laeliinae, Pleurothallidinae, Bulbophyllinae, Lycastinae, and Maxillariinae. With the exception of the pantropical genera Bulbophyllum and Polystachya and the Paleotropical subtribe Coelogyninae, tilosomes are almost exclusively Neotropical phenomena.
VASCULAR PATTERNS IN STEMS OF THE CYCLANTHACEAE
Authors: French J. C. , Clancy K. , Tomlinson P. B.
Published: January 2018

A survey was made of the distribution of stem vascular bundles in representatives of ten genera of the tropical monocotyledonous family Cyclanthaceae. Films of series of serial transverse sections were used to reconstruct the stem vasculature. Each leaf trace, followed in a basipetal direction from its level of insertion at the stem periphery, describes an obliquely downward course, initially contacting from 1 to 4 (or more) existing axial bundles. The associated bundles form a compound vascular bundle in which the original bundles initially remain discrete, most commonly in a tetrapolar arrangement, with four separate strands. Followed further in the basipetal direction, the strands eventually fuse partly or completely, usually to form a collateral or amphivasal axial bundle which participates in a new structural cycle. Quantitative variation between different taxa includes a simple pattern in Ludovia, in which only bipolar bundles are developed. More elaborate forms have multipolar bundles with more than four separate strands. A systematically useful observation is that stem vasculature in Cyclanthus, representing the subfamily Cyclanthoideae, does not differ significantly from that in subfamily Carludovicoideae although there are some distinctive structural features.
THE GRANULAR INTERSTITIUM IN THE POLLEN OF SUBFAMILY PAPILIONOIDEAE (LEGUMINOSAE)
Authors: Ferguson I. K. , Skvarla J. J.
Published: January 2018

A wide range of transitional forms of granular interstitia from simple to complex and from random to ordered occur in the pollen of the subfamily Papilionoideae. Three main types are described: 1) large, widely spaced irregular granules (Type A); 2) densely packed groups of columellae and granules (Type B); and 3) a mass of more or less disorganized granules (Type C). In the genus Calopogonium (tribe Phaseoleae) all three types have been found in different species. Two of the types have been found in different species of the genus Psoralea (tribe Psoraleeae). Granular structures so far occur in six tribes: Desmodieae, Indigofereae, Loteae, Phaseoleae, Psoraleeae, and Vicieae. All of the tribes are regarded as being evolutionarily advanced in both macro and micro characters and many, but not all, show specialized pollen characters. It is concluded that the granular interstitium is a derived structure in papilionoid legumes.
THE VARIABILITY OF NUCLEAR DNA AND ITS IMPLICATIONS FOR POLYPLOIDY IN WHITE ASH (FRAXINUS AMERICANA L.: OLEACEAE)
Authors: Black Candace L. , Beckmann Robert L.
Published: January 2018

Cytophotometric studies of both mature and embryonic tissues of white ash (Fraxinus americana L.) revealed considerable variability of nuclear DNA content in this dioecious polyploid species (2n = 46, 92, 138). Triploid and pentaploid embryos may be produced, and mature individuals of these odd ploidy levels, in turn, may occur in natural populations. Polyploidy may have originated in this species through the union of unreduced gametes.
POPULATION VARIABILITY IN DANTHONIA CAESPITOSA (GRAMINEAE) IN RESPONSES TO INCREASING DENSITY UNDER THREE TEMPERATURE REGIMES
Authors: Quinn James A. , Hodgkinson Ken C.
Published: January 2018

The objective of this research was to compare the responses to increasing density of different natural populations of Danthonia caespitosa, a perennial grass of southern Australia, under different temperature regimes. Seeds were collected from four populations along a 167‐km N–S transect beginning north of Deniliquin, N.S.W., and ending near Heathcote, Victoria. Seedlings from each population were planted in loamy sand at three densities and grown under day/night temperature regimes of 15/10, 24/19, and 33/28 C in the Canberra Ceres Phytotron. Results indicate that one natural population (or one temperature regime) can not be used to characterize this species' responses to increasing density. The effects of density and temperature on tillering, plant height, leaf length, and leaf width varied significantly among populations, so that populations achieved comparable shoot weights by different relative responses to density. Variability in biomass among individuals (as indicated by coefficients of variation) increased from low to intermediate density; however, size variability at the highest density was either greater, lesser, or approximately the same as that of plants at the intermediate density, depending upon the population and the temperature regime. The combinations of density and temperature which produced the maximum shoot growth per pot varied markedly among populations; at 24/19 C, populations from frequently disturbed areas of low perennial plant cover had greater shoot weights per pot at the intermediate density, while those populations from more stable grassland sites had their greatest shoot weights at the highest density. Flowering occurred in all populations at the low density in 15/10 C; however, only for the population from the ungrazed grassland was there any flowering in the other temperature regimes or at higher densities. It is concluded that a “response to density stress” could be differentially described for each population at each temperature regime, even though the four study populations represented only 1/10 of the latitudinal range of D. caespitosa.
CHROMOSOME NUMBER DETERMINATIONS IN ASTER L. (COMPOSITAE) WITH COMMENTS ON CYTOGEOGRAPHY, PHYLOGENY AND CHROMOSOME MORPHOLOGY
Authors: Semple John C. , Chmielewski Jerry G. , Chinnappa C. C.
Published: January 2018

Chromosome number determinations from 360 individuals of 73 species, varieties and hybrids of Aster (not including Virgulus Raf.) are reported for the first time. Most reports confirm one or more earlier ones for the taxa. Several first counts are included: A. curtisii T. & G., 2n = 32; A. drummondii Lindl. var. drummondii, 2n = 16; A. eulae Shinners, 2n = 48; A. infirmus Michx., 2n = 18; A. lateriflorus (L.) Britt., 2n = 64; A. meritus A. Nels., 2n = 36; A. parviceps (Burg.) Macken. & Bush, 2n = 32; A. pubentior Cronq., 2n = 18; and A. sagittifolius Wedem., 2n = 48. Counts of 2n = 18 for A. avitus Alex. and A. hemisphaericus Alex. and 2n = 36 for A. paludosus Ait. provide additional evidence that the base number of A. sect. Heleastrum is x = 9, not x = 5. Counts of 2n = 32 and 2n = 48 for A. curtisii support its placement with other x = 8 species in sect. Foliacei, but not with x = 9 species in sect. Spectabiles. The geographic distributions of cytotypes support the taxonomic delimitations A. puniceus L. and A. praealtus Poir. Diploids were found throughout the range of A. puniceus, but tetraploids were rare and found only in the southwestern portion of the range; ploidy level did not correlate with morphological variation. In A. praealtus the distribution of tetraploids and octoploids correlated with the allopatric varities praealtus and angustior Wieg. Satellite chromosome morphology was determined in species not studied before. Aster engelmannii, A. glaucodes, A. infirmus, A. modestus, A. oregonensis, A. pauciflorus and A. pubentior had subequal satellites and short arms, the “primitive” type in the genus. Aster meritus, A. radula and A. radulina had the “derived,” subg. Aster type, a very large satellite attached to a very short proximal portion of the short arm.
POLLINATION IN THE GENUS ISOTRIA (ORCHIDACEAE)
Authors: Mehrhoff Loyal A.
Published: January 2018

Two closely related North American orchid species, Isotria verticillata and I. medeoloides, were studied with respect to breeding system biology and pollination dynamics. Marked differences in reproductive biology were revealed. The more common I. verticillata is xenogamous, being pollinated by solitary bees in the Andrenidae, Anthophoridae, and Halictidae. The inflorescence is fragrant, multicolored, and has pollination guides, thus possessing an obvious attractant system, even though it lacks nectaries. In contrast, I. medeoloides is self‐pollinating, has light green flowers, and lacks pollination guides, nectaries, and odor. These two species also differ radically in population structure and reproductive efficiency.
SEED DISPERSAL OF TRILLIUM OVATUM (LILIACEAE) IN SECOND‐GROWTH REDWOOD FORESTS
Authors: Mesler Michael R. , Lu Karen L.
Published: January 2018

Trillium ovatum (Liliaceae) is myrmecochorous: its seeds bear large elaiosomes that are attractive to ants. Nevertheless, in coastal second‐growth redwood forests of northern California, most seedlings occur in mixed‐age clusters close to potential parents, suggesting that seed dispersal is limited. Ants were absent or rare at two relatively cool, moist study sites. At these sites, most seeds either eventually fell passively from fruits or were knocked to the ground by banana slugs that foraged on the elaiosomes. At two warmer, drier sites, a single species of ant, Lasius pallitarsis, dispersed the seeds but tended to remove the elaiosomes before returning to the nest. Thus at all sites a large number of seeds remained close to adults, accounting for the observed pattern of seedling distribution. The dispersal adaptations of T. ovatum and other redwood forest myrmecochores probably evolved in forests where seed‐carrying ants were more common.
A COMPARISON OF CLEISTOGAMOUS AND CHASMOGAMOUS FLORAL DEVELOPMENT IN COLLOMIA GRANDIFLORA DOUGL. EX LINDL. (POLEMONIACEAE)
Authors: Minter T. C. , Lord E. M.
Published: January 2018

An individual of Collomia grandiflora typically produces both closed or cleistogamous (CL) and open or chasmogamous (CH) flowers. The developmental origin of these dimorphic floral types within a plant was investigated using histological techniques, allometric relationships, and scanning electron microscopy. Prior to archesporal cell stage in the anthers, CL and CH meristems are indistinguishable. In the CL anther, an absence of ventral locule cell differentiation together with a shorter period of time between archesporial cell differentiation and meiosis in the two dorsal locules results in accelerated anther dehiscence and a smaller mature anther size and pollen grain number. Divergence between the CL and CH patterns of corolla development is coincident with microspore mitosis in the CH anther. At this point, there is an increase in growth in corolla length relative to growth in calyx length in the CH flower which does not occur in the CL flower. Calyx and ovary development are similar in the two floral forms; however, ovary expansion due to fertilization occurs earlier in the CL flower as a result of precocious anther development and stigma receptivity. The hypothesis that anther differentiation may trigger organ growth rate changes and differentiation events in the flower and hypothetical roles for abscisic acid and gibberellin in modifying floral development in C. grandiflora are discussed.
SPRING GROWTH OF SHOOTS AND ROOTS IN SHRUBS OF AN ALASKAN MUSKEG
Authors: Kummerow Jochen , Ellis Barbara A. , Kummerow Susan , Chapin F. Stuart
Published: January 2018

Early spring shoot and fine‐root development of four evergreen and three deciduous shrub species were analyzed in a subarctic muskeg at Fairbanks, Alaska. The overwintered foliage of the evergreen shrubs regreened earlier than new leaves developed on the deciduous species. Likewise, the evergreen shrubs produced new fine roots earlier than the deciduous species. The total nonstructural carbohydrate (TNC) concentration did not decline in the evergreen shrub Ledum palustre during the spring development. This contrasted with the deciduous shrub Betula glandulosa, where a significant TNC reduction in stem tissue coincided with bud break and fine‐root growth flush.
ON THE DEVELOPMENT OF MACROSCLEREIDS IN SEED COATS OF PISUM SATIVUM L.
Authors: Harris William M.
Published: January 2018

Macrosclereid differentiation was investigated by light and electron microscopy in pea testae during the transformation of protodermal precursors to the mature sclereids. The protodermal cells divide anticlinally and elongate into the macrosclereid layer during seed coat development. Young sclereids have elongate nuclei, plastids become somewhat granal during cellular maturation, vacuolation appears to be an autolytic process, and the cells have dense arrays of endoplasmic reticulum and ribosomes. Considerable dictyosome activity and microtubule development is observed as the secondary wall is produced. Many coated vesicles are associated with and fuse with the plasmalemma. During development, the outer tangential wall area of the macrosclereids acquires a definite cuticle and subcuticular layer. Also, at this time the sclereid walls under the subcuticular layer display semicircular microfibril orientation. The sclereid walls adjacent to the hypodermis become multilayered. As the macrosclereids near maturity, the “light line” becomes discernable in the light microscope at the junction of the cellulosic tips of the macrosclereids and the subcuticular layer. This “light line” is prominent using interference optics and is an osmiophilic layer in the electron microscope. This layer may represent the suberin “caps” reported by earlier workers.
THE OCCURRENCE AND PHYLOGENETIC SIGNIFICANCE OF PUTATIVE PLACENTAL TRANSFER CELLS IN THE GREEN ALGA COLEOCHAETE
Authors: Graham Linda E. , Wilcox Lee W.
Published: January 2018

Following fertilization, zygotes of the green algaColeochaete orbicularis, which are retained on the haploid thallus, first enlarge, then become covered with a layer of vegetative cells. Light microscopy and high‐voltage electron microscopy revealed the presence of localized wall ingrowths in vegetative cells adjacent to zygotes. These covering cells resemble the gametophytic placental transfer cells of embryophytes in their morphology, location, and time of development. IfColeochaetecells with wall protuberances function as do placental transfer cells of embryophytes, their presence is evidence that photosynthates may be transported between haploid thallus cells and zygotes. Thus, a nutritional relationship between different phases of the life cycle, similar to that which occurs in embryophytes, may also have evolved in green algae. This first report of putative placental transfer cells in a green alga supports Bower's (1908) ideas concerning the origin of land plant sporophytes and alternation of generations. The presence or absence of cells with wall ingrowths in several species ofColeochaetewas correlated with estimates of zygote‐plant area ratios.
SYSTEMATICS OF THE ZYGNEMATACEAE (CHLOROPHYCEAE). III. TRANSEAU COLLECTION OF THE ZYGNEMATACEAE: AN OLD COLLECTION WITH MODERN USES
Authors: Hoshaw Robert W.
Published: January 2018

Edgar Nelson Transeau, botanist‐ecologist‐phycologist, accumulated a worldwide collection of algal specimens for the compilation of a monograph on the algal family Zygnemataceae, published in 1951. Following his death on January 26, 1960 this Collection remained at The Ohio State University, Columbus until 1978 when it was transferred to the University of Arizona, Tucson. A set of glycerine‐preserved specimens on microscope slides is the major item of the Collection with the number of species represented as follows: Spirogyra (138), Mougeotia (52), Zygnema (45), Zygnemopsis (16), Sirogonium (9), Debarya (9), Zygogonium (4), Mougeotiopsis (1) and Entransia (1). All specimens of Pleurodiscus, Sirocladium, Temnogametum and Temnogyra are unidentified. With the Transeau Collection it was demonstrated that an old collection need not be an historical relic, but does have continued usefulness. Potential future use is a powerful justification for maintaining seemingly useless collections whose accumulation often represents the expenditure of untold time, effort and money on the part of many persons and institutions worldwide. Further, as man continues to alter his environment and species are destroyed, collections with long histories become increasingly more valuable. Specimens of the Transeau Collection were subjected to modern techniques, not available earlier, resulting in improved characterization of zygospore‐wall structure by scanning electron microscopy and the determination of nuclear DNA by cytofluorometry.
POLLEN ULTRASTRUCTURE OF THE TRIBE INGEAE (MIMOSOIDEAE: LEGUMINOSAE)
Authors: Niezgoda Christine J. , Feuer Sylvia M. , Nevling Lorin I.
Published: January 2018

All genera within the Ingeae, excluding Wallaceodendron, were examined with the transmission electron microscope. Thin sections reveal two pollen types (Types I and II) distinguished primarily by differences in polyad cohesion and ektexine organization. Type I polyads (only eight‐grained species of Calliandra) are calymmate and the ektexine of individual cells is continuous around the grain, organized into a thin, foraminate tectum, irregularly shaped, often basally flared, foraminate columellae and thin, discontinuous foot layer. Type II polyads (16‐grained species of Calliandra and remaining Ingeae) are predominantly acalymmate with individual grains typically free from one another or rarely, partially calymmate, i.e., individual grains show limited forms of attachment through small endexinous bridges (Pithecellobium latifolium [Zygia], Lysiloma) or localized appression of adjacent endexines (Pithecellobium daulense [Cathormion]). The adhesion of individual grains through localized fusion of lateral‐distal and proximal ektexine in Enterolobium is unique among the partially calymmate Type II polyads. Ektexine in Type II polyads, largely restricted to the distal face, is composed of a thick, channeled tectum, granular interstitium and when present, thin discontinuous foot layer. Lateral‐distal and proximal areas exhibit only endexine and, occasionally, a foot layer. The occurrence of nondistal ektexine is restricted to Enterolobium. The pollen data suggest that the acalymmate Ingeae polyads composed of grains with porate apertures, thick, highly channeled tectum, granular interstitium and lack of, or greatly reduced foot layer, are clearly derived within the Mimosoideae. Type I calymmate polyads appear to be independently derived. Ultrastructural data suggest that the Ingeae, excluding the eight‐grained Calliandra species, represent a natural grouping with a close affinity to the Acacieae.
INDETERMINATE GROWTH AND RAMIFICATION OF THE CLIMBING LEAVES OF LYGODIUM JAPONICUM (SCHIZAEACEAE)
Authors: Mueller Richard J.
Published: January 2018

Morphological and anatomical specializations of the climbing leaves (CL) of Lygodium japonicum were investigated. Examination of growth relationships between the rachis and pinnae of the circumnutating CL revealed a close relationship to the “searcher” morphology of twining shoots. The CL has resting pinna apices (leafbuds) capable of replacing a damaged leaf apex or ramifying the foliar axis. Their structure and growth is similar to the main leaf apex. CL growth is indeterminate and occurs at a steady rate. Crozier uncoiling and rachis elongation occurs by a mechanism of unequal rates of cell division and elongation. The adaptations of the CL are interpreted as specializations within the basic principles of fern leaf morphogenesis.
CHROMOSOME RACES AND STRUCTURAL HETEROZYGOSITY IN CALYCADENIA CILIOSA GREENE (ASTERACEAE)
Authors: Carr Robert L. , Carr Gerald D.
Published: January 2018

A biosystematic study of Calycadenia ciliosa resulted in the recognition of five homoploid (n = 6) chromosome races. The cytogenetic evidence indicates that each of these races is differentiated from its nearest relative by a single reciprocal chromosome translocation, although at one point in the evolutionary history a pericentric inversion may have been a concurrent cytological event. The data also show that the chromosome phylogeny includes two instances of redundant translocation. Mean pollen stainabilities of interracial hybrids range from 16–80%. In a survey of four natural populations 30–60% of the individuals sampled were found to be structurally heterozygous for reciprocal chromosome translocations. Pericentric inversion heterozygosity was also detected in one population. Another population contained morphologically indistinguishable individuals separated by as little as 120 m that were differentiated by a minimum of four chromosome translocations. These observations were compared with similar instances in other species in an effort to determine their significance in the process of plant evolution.
VASCULAR PATTERNS IN STEMS OF ARACEAE: SUBFAMILIES COLOCASIOIDEAE, AROIDEAE AND PISTIOIDEAE
Authors: French J. C. , Tomlinson P. B.
Published: January 2018

The stem vasculature of ten genera of Colocasioideae and three genera of Aroideae was analyzed by films of series of cross sections. The technique was unsuited for the numerous tuberous genera of Aroideae (and Pistia), which have shortened internodes. The Colocasioideae has long been recognized as one of the most natural large assemblages in the Araceae, a concept further supported by information from stem anatomy and vasculature. All species examined have amphivasal axial bundles that undergo frequent anastomosis and bifurcation of a seemingly irregular kind. Syngonium is the only viny genus and is exceptional in a number of anatomical features which are associated with its unusual morphology. One of the principle points of diversity in the Colocasioideae is the presence or absence of a permanent cortical vascular system. All four genera with a permanent cortical system (Caladiopsis, Caladium, Xanthosoma, and Syngonium) are neotropical. In the Aroideae (and Pistioideae) all of the tuberous genera have a highly condensed vascular system. Genera with elongated internodes (Stylochiton, Lagenandra, Cryptocoryne) also have a similar pattern, which makes taxonomic comparisons based on stem vasculature in the Aroideae of little value. Branch trace insertion is much less well developed in Colocasioideae and Aroideae than in most other subfamilies.
CHEMICAL VARIATION IN NOTHOLAENA STANDLEYI
Authors: Seigler David S. , Wollenweber E.
Published: January 2018

In Notholaena standleyi (Pteridaceae), differences in geographic range, aspect, height, edaphic requirements, and the color and chemistry of the ceraceous exudate on the abaxial side of the frond suggest at least three distinct subgroups of this taxon. One race, with a light yellow exudate consisting mostly of kaempferol, 3‐O‐methylkaempferol and 4'‐O‐methylkaempferol occurs in the eastern portion of the range. A yellow‐green race and a gold race possess mostly 7‐O‐methylkaempferol and 4'‐O‐methylkaempferol but also the uncommon compounds 7‐O‐methylherbacetin and 7,4'‐di‐O‐methylherbacetin. Plants of the yellow‐green race produce minor constituents with methyl substituents in the 3‐position whereas those of the gold race lack them. Plants of this last group produce only traces of kaempferol.

Principal Components Analysis based on nine flavonoid constituents and 59 samples was carried out. Plants of the three groups clustered in plots of Principal Components 1 vs. 2, 1 vs. 3, and 2 vs. 3 and were separated from each other.

These plants reproduce ameiotically and thus there is little or no gene flow among them and they are geographically distinct. We prefer to maintain them as informally recognized taxa pending further studies.
ELECTROPHORETIC ANALYSIS OF SOLUBLE ENZYMES IN FIVE FRESHWATER DINOFLAGELLATE SPECIES
Authors: Hayhome B. A. , Pfiester Lois A.
Published: January 2018

Electrophoretic analysis of 11 different clonal freshwaterPeridiniumisolates shows that currently used morphological taxonomic criteria are conservative measures of relatedness and that the presence or absence of an apical pore is an important taxonomic feature. Correlation of malate dehydrogenase and glutamate dehydrogenase isoenzyme patterns with chromosome number variations among our isolates lends no support to polyploidy as a speciation mechanism.
NUTRIENT LEVELS IN CACTI—RELATION TO NOCTURNAL ACID ACCUMULATION AND GROWTH
Authors: Nobel Park S.
Published: January 2018

The levels of ten essential nutrients and Na in the chlorenchyma and subjacent parenchyma of ten species of cacti were measured along with the maximal rates of nocturnal acid accumulation. Nutrient levels varied considerably among species; also, soil differences between sites affected levels within Opuntia ficus‐indica and O. chlorotica. Compared to most agronomic plants, chlorenchyma levels of Ca, Mg, and Mn in cacti tended to be higher and Na lower. Moreover, Ca tended to accumulate in the chlorenchyma with age. The strongest correlation between nutrient level and a metabolic process for the 11 elements tested was with N, where nocturnal acid accumulation tended to be greater when the N level in the chlorenchyma was higher (r2 = 0.39). Hydroponically grown seedlings of Carnegiea gigantea, Ferocactus acanthodes, and Trichocereus chilensis responded to N fertilization, reaching about 90% of their maximal growth rates when provided with N at 0.25 x that in Hoagland's solution (namely, 4 mm nitrate). Nocturnal acid accumulation was negatively correlated with the chlorenchyma Na (r2 = 0.32), which averaged only 28 ppm for O. ficus‐indica (the root contained considerably more) and 234 ppm for the other species. Growth of seedlings was 50% reduced at about 100 mm NaCl for F. acanthodes, T. chilensis, and C. gigantea, while variations in P had a relatively small effect.
THE APEX OF STIGMARIA (LYCOPSIDA), ROOTING ORGAN OF LEPIDODENDRALES
Authors: Rothwell Gar W.
Published: January 2018

An apical segment of Stigmaria ficoides recently has been located among specimens from Pennsylvanian sediments of Iowa, and provides the first indisputable structural evidence for apical organization and development in one of the most enigmatic of all tracheophyte organs. Toward the apex, the specimen tapers to a circular rim. Rootlet scars occur in a helical arrangement from the proximal end of the specimen to the margin of the rim. Within the rim there is a discontinuous groove that surrounds an irregularly concave apex. The specimen compares favorably with the rooting apex of young Nathorstiana specimens, and adds to our knowledge of homologies among lycophyte rhizomorphs with axial elongation.
INTRASPECIFIC VARIATION IN ABIES LASIOCARPA FROM BRITISH COLUMBIA AND WASHINGTON
Authors: Parker William H. , Maze Jack
Published: January 2018

Sixteen natural stands of Abies lasiocarpa (Hook.) Nutt. were sampled from British Columbia and Washington to investigate patterns of intraspecific variation in this species and to evaluate Hunt and von Rudloff's recognition of two species of subalpine fir. Principal components analysis and canonical variates analysis were performed separately on seed‐cone data, needle morphology data, and needle flavonoid data. Analysis of cone data indicated no geographical patterning of populations, but eastern and western groups of populations were segregated in both the needle morphology and flavonoid analyses. With the exception of the Vancouver Island population, three geographic groups were discerned based on their needle morphology: 1) populations from the coastal mountains of British Columbia, 2) those from the Cascade Mountains of Washington, and 3) those from the eastern interior of British Columbia. Although the Vancouver Island population was grouped with the interior British Columbia populations based on needle morphology, it was similar to the other coastal populations based on flavonoid data. These inconsistent results among the three different types of taxonomic evidence underscore the need to consider a variety of traits when drawing taxonomic conclusions in Abies. Although the delineation of eastern and western groups is not wholly consistent for the different data sets, the results support recognition of coastal and interior varieties of subalpine fir.
ROOT CONTRACTION IN HYACINTH. I. EFFECTS OF IAA ON DIFFERENTIAL CELL EXPANSION
Authors: Jernstedt Judith A.
Published: January 2018

Contractile roots of Hyacinthus orientalis L. cv ‘Pink Pearl’ shorten as a result of growth of inner cortical cells which expand radially and contract longitudinally. Brief treatment with IAA (indole‐3‐acetic acid—0.5 and 1.0 mg/1) induces subapical swelling, root cap proliferation and decreased rates of elongation in potentially contractile roots. Growth resumes with removal of IAA from the culture medium and contraction subsequently occurs. The pattern of subsequent contraction is affected by prior IAA treatment; contraction occurs in the normal manner both acropetal and basipetal to the points of IAA‐induced swelling, but does not occur in the swollen region itself. Microscopic examination of the swollen region reveals that cells of the middle and outer cortex are radially expanded and longitudinally shortened relative to middle and outer cortical cells of contracted and uncontracted portions of the same root and control roots. In contrast, inner cortical cells in swollen regions of IAA‐treated roots show approximately 50% less radial expansion than inner cortical cells of control contracted roots. Middle and outer cortical cells in the swollen region of IAA‐treated roots undergo radial expansion, while middle and outer cortical cells in adjacent contracting zones are compressed by radially expanding inner cortical cells. Average volumes of cortical cells in the IAA‐induced swollen region increased approximately two‐fold when contraction occurred in adjacent regions. These results suggest that in hyacinth roots, under certain circumstances, inner and outer cortical cells alike possess the ability for growth reorientation and expansion. However, during the usual course of contractile root development, cells of the outer cortex are restricted in this ability, through an as yet unknown mechanism, and are passively compressed by the radially expanding inner cortical cells.
OCCURRENCE OF INTERCALARY AND UNINTERRUPTED MERISTEMS IN EQUISETUM
Authors: French James C.
Published: January 2018

Quantitative data on cell length and mitotic index in elongating internodes of seven species of Equisetum are presented as evidence for the occurrence of two patterns of internode development in rhizomes of different species. In rhizomes of three species of subgenus Equisetum (E. arvense, E. diffusum, E. telmateia) uninterrupted meristems are present, characterized by acropetal internode maturation. In rhizomes of four species of subgenus Hippochaetae (E. hyemale, E. variegatum, E. scripoides, and E. laevigatum) intercalary meristems are present. The number and locations of intercalary meristems are described for an aerial shoot of E. diffusum. The absence or diminution of intercalary meristems from rhizomes of a variety of vascular plants with intercalary meristems in aerial shoots is discussed from the standpoint of adaptive significance.
VASCULARIZATION OF DEVELOPING LEAVES OF GLEDITSIA TRIACANTHOS L. I. THE NODE, RACHIS, AND RACHILLAE
Authors: Larson Philip R.
Published: January 2018

Leaves of Gleditsia triacanthos L. are served by three leaf traces that subdivide in the node to produce subsidiary bundles. The subsidiary bundles differentiate basipetally in the stem and acropetally in the petiole using the original leaf trace bundles (those that developed acropetally) as templates for their development. Within the pulvinus, the acropetal bundle components merge to form the rachis vasculature consisting of a semicircular arc and a ventral chord; several small bundles diverge to form ventral ridge bundles. Mixing of bundles occurs during vascularization of the lateral rachillae axes. Each diverging rachilla axis receives bundles from the semicircular arc, the ventral chord, and a ridge bundle in a relatively reproducible and predictable pattern. During this process the main rachis vasculature is gradually depleted, but the ridge bundles are reconstituted following divergence of each rachilla pair. The distal rachilla pair is vascularized by a bilateral partitioning of the entire rachis vasculature; a remnant of the central leaf trace terminates in a subulate terminal appendage. Vascularization of the bipinnate G. triacanthos leaf is compared to that of the simple Populus deltoides leaf.
ULTRASTRUCTURE OF CARPOSPOROGENESIS IN THE PARASITIC RED ALGA FAUCHEOCOLAX ATTENUATA SETCH. (RHODYMENIALES, RHODYMENIACEAE)
Authors: Delivopoulos Stylianos G. , Kugrens Paul
Published: January 2018

Carpospore differentiation inFaucheocolax attenuataSetch. can be separated into three developmental stages. Immediately after cleaving from the multinucleate gonimoblast cell, young carpospores are embedded within confluent mucilage produced by gonimoblast cells. These carpospores contain a large nucleus, few starch grains, concentric lamellae, as well as proplastids with a peripheral thylakoid and occasionally some internal (photosynthetic) thylakoids. Proplastids also contain concentric lamellar bodies. Mucilage with a reticulate fibrous substructure is formed within cytoplasmic concentric membranes, thus giving rise to mucilage sacs. Subsequently, these mucilage sacs release their contents, forming an initial reticulate deposition of carpospore wall material. Dictyosome vesicles with large, single dark‐staining granules also contribute to wall formation and may create a separating layer between the mucilage and carpospore wall. During the latter stages of young carpospores, starch is polymerized in the perinuclear cytoplasmic area and is in close contact with endoplasmic reticulum. Intermediate‐aged carpospores continue their starch polymerization. Dictyosomes deposit more wall material, in addition to forming fibrous vacuoles. Proplastids form thylakoids from concentric lamellar bodies. Mature carpospores are surrounded by a two‐layered carpospore wall. Cytoplasmic constituents include large floridean starch granules, peripheral fibrous vacuoles, mature chloroplasts and curved dictyosomes that produce cored vesicles which in turn are transformed into adhesive vesicles. Pit connections remain intact between carpospores but begin to degenerate. This degeneration appears to be mediated by microtubules.
THE RELATIONSHIP BETWEEN THE PRIMARY THICKENING MERISTEM AND THE SECONDARY THICKENING MERISTEM IN YUCCA WHIPPLEI TORR. III. OBSERVATIONS FROM HISTOCHEMISTRY AND AUTORADIOGRAPHY
Authors: DeMason Darleen A. , Diggle Pamela K.
Published: January 2018

Observations were made of stem sections stained for RNA and protein of Yucca whipplei ranging from germinated seedlings to 6‐month‐old plants. One‐, two‐, and three‐month‐old plants were labeled with tritiated thymidine, fixed in FAA, sectioned, stained with the Feulgen reaction, and prepared for autoradiography. The serial transverse sections were outlined with a drawing tube recording all labeled nuclei on a computer graphics tablet. Computer‐assisted three‐dimensional reconstructions were made to observe the locations of labeled nuclei. The two techniques are in agreement: the thickening meristem is broad near the top of the stem, occupies a narrower band at more basipetal levels, and disappears below the level of recent root initiation. There are no gaps in staining or labeling, and there are no changes in staining or labeling that would distinguish between the activities of the primary thickening meristem and the secondary thickening meristem in those plants which possess both. The meristems are continuous at all stages of development in the young vegetative stem. The STM is interpreted to be a developmental continuation of the PTM.
STUDIES OF PALEOZOIC FUNGI. III. FUNGAL PARASITISM IN A PENNSYLVANIAN GYMNOSPERM
Authors: Stubblefield Sara P. , Taylor Thomas N. , Miller Charles E. , Cole Garry T.
Published: January 2018

Evidence of fungal parasitism is found in the Pennsylvanian gymnospermous cone, Lasiostrobus polysacci Taylor. Indication of fungal activity is found in the outer cortical region of the axis of the cone and in the fleshy microsporophylls. Specimens exhibit severe tissue disruption, thick‐walled, branched, septate hyphae, and possible reproductive structures. Parenchymatous cortical cells may also contain rounded bodies which are continuous with the cell wall. Similar structures are formed in many extant taxa in response to fungal invasion, and are termed wall appositions or callosities. Although their role in extant plants is disputed, they are clearly the product of a living host cell. Such spherical bodies, however, are not restricted to the cell periphery but in some cases occlude the cell lumen. In appearance they resemble resinous remains similar to those found in other coal ball plants. The blockage of entire cells or groups of cells may have served to retard hyphal growth or isolate infected cells. The occurrence of such structures in a Carboniferous plant provides the best evidence to date of parasitism during the Paleozoic.
THE EFFECT OF SEED SIZE AND MATERNAL SOURCE ON INDIVIDUAL SIZE IN A POPULATION OF LUDWIGIA LEPTOCARPA (ONAGRACEAE)
Authors: Dolan Rebecca Wilcox
Published: January 2018

Seed size is normally distributed for many annual species, while mature plant size is frequently positively skewed. A study was conducted to determine the influence of seed size and the role of genetic differences in determining relative seedling size for Ludwigia leptocarpa. Seed size had a significant effect on percentage germination and time of seed germination but no effect on dry weight or leaf area of seedlings. Seed size and spacing had a significant effect on seedling dry weight for plants grown under competition, while relative day of emergence had no effect. Familial (genetic) differences were found in average seed weight between maternal plants, but not in average number of days to germination, average weight of seeds which germinated, or shoot dry weight. It is concluded that neither seed size alone nor genetic differences between plants are directly responsible for the development of size hierarchies in Ludwigia leptocarpa populations. Large seed size does convey an advantage in growth when plants from seeds of differing initial size interact.
PHOTOTROPISM OF SELAGINELLA: THE DIFFERENTIAL RESPONSE TO LIGHT
Authors: Bilderback D. E.
Published: January 2018

Selaginella kraussiana (Kunze) A. Braun has a plagiotropic dorsiventral stem with two rows of small leaves on the dorsal surface and two rows of large leaves inserted laterally. Stem tips exhibit a differential phototropic response. When stem tips are placed in their normal horizontal orientation and the dorsal surfaces are illumianted, the tips bend only 20” below the horizon and away from light. Stem curvature is limited to a zone 450 μm long located 1.5 mm behind the shoot apex. The dorsal cortical cells within this zone of curvature are about 1.44 times longer than the ventral cortical cells. Illumination of the ventral surface of the stem tips elicits a strong phototropic response. The stems bend from 123–158° below the horizon and toward light, and the zone of curvature increases in length to 10 mm of the explant. The curvature is large enough so that the previously shaded dorsal leaves of the stem tips become redirected toward the light. This phototropic response is promoted by white and blue light, whereas red or far‐red light has no effect. When stem tips are cultured in total darkness, the length of the zone of curvature is 8.0 mm but the stems bend only 50–67°. Treatment of the small dorsal leaves with phenylacetic acid inhibits phototropic curvature, and the phototropic response is unaffected by gravity.