bluuebunny/crossref_metadata_2025 huggingface dataset:
FACTORS AFFECTING DORMANCY, GERMINATION, AND SEEDLING DEVELOPMENT OF AEGINETIA INDICA L. (OROBANCHACEAE)
Authors: French R. C. , Sherman L. J.
Published: January 2018

Dormancy in seeds of the parasitic phanerogam Aeginetia indica L. can be broken by chemical treatment with sodium hypochlorite, which also helps to control contaminating microflora. A germination medium was developed that suppressed microbial contamination and permitted long‐term observation of these slow‐germinating seeds. The medium consisted of 10 ppm streptomycin, 10 ppm penicillin, and 10−5 m indole‐3‐acetic acid (IAA) (or other growth regulator) in 1 % water agar. Optimum germination range was 25–30 C. Dormancy could also be broken by exposure on agar for several days at 3‐5 C (stratification), or by brief exposures (15 min) to 50 C. Continuous light as low as 0.1 ft‐c completely inhibited germination on this growth medium. Brief, intermittent light exposures depressed germination. Germination and growth in vitro of nondormant seed of Aeginetina indica L. can be described in five stages: (1) Germination: expansion of spheroidal cells or nodule at micropylar end of the seed, stimulated by growth regulators. Unique stimulation of germination by IAA was noted; (2) Tendril formation: production of a root‐hairlike protrusion in response to seedling roots or extract of pea seedlings; (3 and 4) Tendril septation and branching: induced by pea extract; (5) Seedling extension growth: cell growth and division adjacent to nodule by action of various carbohydrate‐containing growth factors. This type of growth may bypass tendril formation.
OBSERVATIONS ON CHYTRIDIACEOUS PARASITES OF PHANEROGAMS. XXV. PHYSODERMA JOHNSII SPARROW, A PARASITE OF CALTHA PALUSTRIS L.
Authors: Sparrow Frederick K.
Published: January 2018

The morphology of the endobiotic and epibiotic stages of Physoderma johnsii Sparrow on Caltha palustris is described. Highly characteristic of the endobiotic stage is the formation of numbers of large, narrowly pyriform cells with a tuft of rhizoids at the broader (distal) end. Early developmental features are not included since germination of the resting spore has not as yet been achieved. Reasons for maintaining this taxon distinct from older ones on Caltha palustris are given.
INFLUENCE OF HORMONAL TREATMENTS ON THE GROWTH OF TWO HALOPHYTIC SPECIES OF SUAEDA
Authors: Boucaud Jean , Ungar Irwin A.
Published: January 2018

Experiments were made to determine the interaction between the growth regulating substances, gibberellic acid and kinetin, and salinity on the growth and development of two species of Suaeda. We found that the growth of Suaeda maritima var. macrocarpa, an obligate halophyte, was greatly stimulated with treatments by both of these hormones in controls not treated with sodium chloride. These results suggest that halophytes grow poorly under nonsaline conditions because of some type of hormonal imbalance. GA3 was found to stimulate growth at all salinities for both S. maritima var. macrocarpa and S. depressa, while kinetin proved to be inhibitory to growth and elongation of plants at higher salinities. Chlorophyll content decreased with salt treatments and was not significantly influenced by hormonal treatments. GA3 had little influence on water content in roots and shoots, whereas plants treated with kinetin generally had reduced water contents.
MORPHOLOGY, FINE STRUCTURE AND ONTOGENY OF THE STINGING EMERGENCE OF TRAGIA RAMOSA AND T. SAXICOLA (EUPHORBIACEAE)
Authors: Thurston E. Laurence
Published: January 2018

The ontogeny and ultrastructure of Tragia ramosa and T. saxicola are described. The stinging emergence of T. ramosa and T. saxicola consists of a central stinging cell and three lateral cells. The stinging cell possesses a compound crystal in the apical region which is held in place by cell wall extensions. The stinging cell cytoplasm is characterized by a large central vacuole which contains a proteinaceous substance as determined histochemically. Upon contact, the stinging cell wall is pushed back over the crystal, exposing it to penetrate an individual. This stinging mechanism is unique among stinging emergences. The stinging cell is subepidermal in origin whereas the three lateral cells are epidermal in origin. The morphology, ultrastructure and ontogeny of the stinging emergence of T. ramosa and T. saxicola appear to be identical.
THE ANATOMY AND THREE‐DIMENSIONAL MORPHOLOGY OF ANNULARIA HOSKINSII SP. N.
Authors: Good Charles W.
Published: January 2018

Foliage attached to calamitean shoots is described from coal ball petrifactions of Middle and Late Pennsylvanian age. Leaves correspond to the compression‐impression genus Annularia and thus represent the first attached members of this genus to be recognized as petrifactions. Individual leaves contain a single unbranched vascular bundle flanked by wide lateral laminar areas which occupy more than half the leaf cross sectional area. Stomata are confined to broad bands within concave furrows which parallel the vascular bundle on the abaxial leaf surface. Epidermal cells within these furrows are in rows aligned obliquely to the leaf axis, and the rows angle outward at a slight angle towards the leaf margin. Convolutions of the leaf‐bearing axes result from nodal diaphragms which are oblique to the shoot axis. Whorled leaves apparently radiate outward in the plane of each obliquely positioned nodal diaphragm. This petrified material helps explain the apparent flattening of entire nodal diaphragms and leaf whorls within the same plane as seen in compression specimens. Annularia hoskinsii sp. n. is proposed, and the systematic position of structurally preserved Annularia foliage relative to the genus Dicalamophyllum is discussed.
CYTOGENETIC STUDIES OF CARTHAMUS DIVARICATUS WITH ELEVEN PAIRS OF CHROMOSOMES AND ITS RELATIONSHIP TO OTHER CARTHAMUS SPECIES (COMPOSITAE)
Authors: Estilai Ali , Knowles P. F.
Published: January 2018

Carthamus divaricatus (Beg. et Vacc.) Pamp., found only in Libya, has 11 pairs of chromosomes, a new chromosome number in the genus. The species is distinct morphologically. It has yellow, purple, and white corollas, yellow pollen, dark‐purple striped anthers, horizontal branches, and strongly divaricate outer involucral bracts. The terminal portion of the middle involucral bracts is dentate and reddish brown. It is self‐incompatible. Meiosis is regular in the different corolla‐color types of C. divaricatus and their intraspecific hybrids. C. divaricatus was crossed to six species with n = 12, to three species with n = 10, to C. lanatus with n = 22, and to two species with n = 32 chromosomes. The morphological characteristics and cross‐ability of the parental species plus the pollen viability, seed‐set, and meiotic behavior of the hybrids involving C. divaricatus and other Carthamus species indicated that C. divaricatus is very closely related to species with n = 10, closely related to C. lanatus with n = 22, and less closely related to C. tinctorius with n = 12 chromosomes. C. divaricatus seems to be distantly related to C. nitidus (n = 12). It is proposed that C. divaricatus be included provisionally with 10‐chromosome species in Section II. Alternative hypotheses for the development of the three basic chromosome numbers are discussed.
STUDIES ON THE MATING SYSTEMS OF ELEVEN SPECIES OF MYXOMYCETES
Authors: Clark Jim , Collins O'Neil Ray
Published: January 2018

Genetic analysis of 20 isolates representing 11 species of Myxomycetes was carried out to determine whether they were heterothallic or homothallic. Each of the single isolates of Badhamia utricularis, Didymium minus, D. nigripes, and Physarum cinereum was found to be heterothallic, the first such reports for all of the species except D. nigripes. All isolates of Badhamia foliicola (1), Didymium squamulosum (1), Physarum compressum (3), P. gyrosum (1), P. pusillum (2), Stemonitis flavogenita (6) and an unidentified species of the order Physarales (2) were homothallic, with B. foliicola, P. compressum, and S. flavogenita being reported for the first time.
ULTRASTRUCTURAL ASPECTS OF EARLY STAGES IN COTTON FIBER ELONGATION
Authors: Ramsey J. C. , Berlin J. D.
Published: January 2018

Fine structural alterations associated with early stages of cotton fiber elongation in Gossypium hirsutum L. var. dunn 56 C occur rapidly following anthesis and appear to be correlated with the formation of the central vacuole, plasma membrane, and primary cell wall as well as with increased protein synthesis necessary for cell elongation. Association of dilated cisternae of the endoplasmic reticulum with the tonoplast suggests that the endoplasmic reticulum is involved in the formation of the central vacuole. Dictyosome involvement in both plasma membrane and primary cell wall formation was suggested from observations of similarities between dictyosome associated vesicles, containing fibrils appearing similar in morphology to fibrils found in the primary cell wall, and plasma membrane associated vesicles. The single nucleolus found in cotton fibers enlarges following anthesis, shows segregation of granular and fibrillar components by 1 day postanthesis, develops a large “vacuole,” thus appearing ring‐shaped, and occupies much of the nuclear volume by 2 days postanthesis. Prominent nucleoli were not observed in nuclei after 10 days postanthesis.
TWO NEGLECTED ASPECTS OF FOSSIL CONIFERS
Authors: Harris Tom M.
Published: January 2018

Most conifers, living and fossil, drop their foliage in one of two natural ways. Either each leaf is abscised separately, or intact leafy shoots are abscised. Thus, a fossil leafy shoot of a leaf‐dropping species is an unusual specimen, and is the result of premature, violent removal, as by storm. Any reproductive organs it bears are likely to be immature. This idea, applied to the ovules of Taxus jurassica Florin leads to their reinterpretation: they prove unlike Taxus, but rather, like Amentotaxus. A few living conifers drop their leaves or leafy shoots at the end of each summer. There may be evidence that a fossil was deciduous. Phyllotaxis has seldom been examined closely in fossil conifers but can be clearly observed even in compressed specimens. Three main kinds occur: 1) Leaves or cone scales are attached singly in a helix (spiral) which is usually very regular. 2) Leaves are attached two (or more) at a node and those of the next node alternate strictly; if there are pairs, the next pair is at 90° decussation. 3) Leaves are in opposite pairs but the next pair is at an angle of less than 90°, and the leaves form a double helix or bijugate spiral. In fossils all three kinds can be subdivided according to the numbers of oblique rows (parastichies) rising to the right and left, in relation to the diameter of the organ. Torreya gracilis Florin (from the Jurassic) proves to have the same phyllotaxis, a double helix, as that found in modern Torreya shoots. But Florin's Taxus jurassica has its leaves in decussate pairs, unlike Taxus, but rather, like Amentotaxus. For this and other reasons it is here renamed Marskea jurassica (Florin) comb. cnov.
GAMETOPHYTES AND SUBGENERIC CONCEPTS IN LYCOPODIUM
Authors: Bruce James G.
Published: January 2018

A critique of the Freeberg and Wetmore work on cultured Lycopodium gametophytes of L. selago, L. flabelliforme, and L. cernuum is presented. All three gametophytes are shown actually to be L. cernuum based on morphological and anatomical features of their sporophytes. A reassessment of characters in the genus demonstrates the taxonomic validity of the three groups proposed as subgenera within Lycopodium.
DCMU INDUCED INHIBITION OF GROWTH, PHOTOSYNTHESIS AND MOTILITY IN EUDORINA ELEGANS CULTURES
Authors: Orr Alan R. , Kessler James E. , TePaske E. R.
Published: January 2018

Studies with Eudorina elegans L. were done to provide additional information on the effect of phenyl urea herbicides on phytoplankton. Colonies were grown in various concentrations of DCMU, 3(3,4‐dichlorophenyl)‐1,1‐dimethylurea. DCMU at 10‐5 m induced an algicidic response. DCMU at 10‐7 M and 10‐9 M caused a significant reduction in the growth of colonies. Photosynthesis was significantly inhibited at all concentrations of DCMU. A rapidly growing population of algae treated with 10‐7 m and 10‐9 m DCMU showed a reduced motile/non‐motile balance of colonies.
MUTATIONAL LOAD IN A FERN POPULATION GROWING IN A POLLUTED ENVIRONMENT
Authors: Klekowski Edward J.
Published: January 2018

The Osmunda regalis sporophyte is well organized for the storage and perpetuation of post‐zygotic mutations. Techniques have been developed to detect sporophytes in which such mutations have occurred. Two populations were screened for sporophytes which are chimeras for gametophytic or recessive sporophytic lethals. The populations had different ecologies; one was in a pristine lake side bog and the other was growing in the waters of a river heavily polluted with industrial wastes. Post‐zygotic mutations were detected only in the polluted river population. The level of mutational damage approximated that previously documented from chromosome studies.
CUTICLES OF TWO SPECIES OF ALETHOPTERIS
Authors: Reihman M. A. , Schabilion J. T.
Published: January 2018

Specimens of Alethopteris sullivanti (Lesquereux) Schimper and Alethopteris lesqueieuxi Wagner were found in Middle Pennsylvanian coal balls from the Lovilia, Iowa and West Mineral, Kansas localities. Light microscopy and scanning electron microscopy (SEM) were used to study macerated cuticles of these two foliage types of the pteridosperm, Medullosa. The lower epidermises of both species of Alethopteris possess sunken stomata, papillae, and evidence of multicellular hairs. The upper epidermises are devoid of these features. Critical point drying and subsequent observation with SEM were used to document the structure of the multicellular hairs of A. lesquereuxi. Replicas of the lower epidermal features of an impression‐compression specimen of A. sullivanti were observed with SEM and compared with the petrified specimens.
REPRODUCTIVE ISOLATION OF TRITICUM BOEOTICUM AND TRITICUM URARTU AND THE ORIGIN OF THE TETRAPLOID WHEATS
Authors: Johnson B. L. , Dhaliwal H. S.
Published: January 2018

The diploid wheats Triticum boeoticum and T. urartu are sympatric with one another throughout the geographic range of the wild tetraploids. Reciprocal crosses between ecogeographic types within each diploid species gave viable seed, but interspecific crosses consistently gave viable seed only when T. boeoticum was the female parent. Apparently urartu cytoplasm in combination with the boeoticum genome resulted in nonviable seed. The endosperm failed to develop normally despite regular endosperm fertilization. The F1 plants obtained were completely self sterile although they showed regular intergenomic pairing (7II) at meiosis. Presumably the accumulation of cryptic differences between the two closely related genomes under reproductive isolation accounts for this sterility. The same accumulated cryptic differences could largely account for the preferential diploid pairing in the tetrapolid wheats which presumably were derived from such hybrids by chromosome doubling. The behavior of reciprocal crosses between the diploids and tetraploids suggested that T. boeoticum contributed the cytoplasm to both of the wild tetraploid species.
REPRODUCTIVE PROFICIENCY IN PAEONIA CALIFORNICA (PAEONIACEAE)
Authors: Schlising Robert A.
Published: January 2018

Study of three populations of geophytic Paeonia californica in southern California revealed considerable variation, within and between populations, in both potential and in realized seed output. Plants are weakly self‐compatible, but natural seed set (x = 4.2 seeds per carpel) is closer to seed set produced in hand cross‐pollinations (x = 4.5) than in self pollinations (x = 1.4). Flowers are protogynous, nectariferous, and scented; 17 species of bees in four families, and one species of melyrid beetle were found in them and probably account for pollinations at these sites. Counts of reproductive parts show greatest inter‐population variation in mean numbers per plant, of flowers (population means ranged from 16.2 to 21.2), ovules (744 to 1142), pollen grains (23 million to 38 million), and % viable pollen (26.6 to 81.4). Seed set also varied significantly, with only 11.4 to 26.8 % of the ovules maturing into seeds. This low reproductive success is probably correlated with the genetic anomalies studied by others—particularly the translocation heterozygosity that causes lowered production of viable gametes. The relatively few seeds produced are heavy (x = 0.184 g per seed), and germination percentages are high (x = 80%). The elongation of cotyledon bases during hypogeal germination seems to permit optimal germination at soil depths of only 2–3 cm, but environmental factors such as drought stress and herbivore pressure promote high seedling mortality.
STUDIES ON THE SELF‐INCOMPATIBILITY RESPONSE OF LILIUM LONGIFLORUM
Authors: Fett William F. , Paxton Jack D. , Dickinson David B.
Published: January 2018

Removal of substances loosely associated with the wall of Lilium longiflorum pollen did not affect in vitro germination and tube growth, tube growth within compatible styles, or production of viable seeds. Nor was growth of pollen tubes within incompatible styles enhanced by prior removal of the loosely bound materials. Hence, these materials appear not to be recognition factors in the gametophytic self‐incompatibility system of Lilium and to have no role in pollen germination. Heat treatment of selected portions of lily pistils prior to pollination indicated that the incompatibility factor(s) was located in the lower half of the style, and that the stigma plays no role in incompatibility.
SEED FERTILITY IN TRAGOPOGON HYBRIDS (COMPOSITAE)
Authors: Fahselt Dianne , Ownbey Marion , Borton Marla
Published: January 2018

The seed fertility of 172 interspecific and 32 intraspecific F1 hybrids in the genus Tragopogon was determined. Intrageneric barriers to interbreeding were variable; some were weak and others quite strong. Maternal influences on fertility were found in 18 pairs of reciprocal interspecific crosses. It was postulated that cytoplasmic and nuclear factors interacted to determine the level of seed fertility. Although F1's were generally sterile or semi‐sterile, the proportion of fertile seeds produced in most crosses increased in the F2 generation. In two cases, however, a significant decrease was observed.
ULTRASTRUCTURAL FEATURES OF DEVELOPING SIEVE ELEMENTS IN LEMNA MINOR L.—SIEVE PLATE AND LATERAL SIEVE AREAS
Authors: Walsh Michael A. , Melaragno Jerry E.
Published: January 2018

Both intact and cut duckweed plants were prepared for electron microscopy. Plants which are prepared intact do not exhibit callose formation during development of sieve‐plate pores. Future pore sites can be recognized by the presence of median cavities that are unassociated with callose platelets. These cavities are first seen in the region of the compound middle lamella and are lined by a plasmalemma. As end walls thicken, the cavities increase in size until open pores of uniform width are formed. Mature sieve plates of intact‐prepared plants are also devoid of callose. Fully opened pores are lined by a plasmalemma and are only traversed by an occasional tubule of endoplasmic reticulum. Plants which have been cut prior to fixation possess mature sieve plates containing callose. The pores of developing sieve plates in cut plants exhibit small amounts of callose. Except for the lack of callose, lateral wall connections between sieve elements and contiguous cells are similar in development and mature state to those reported for other species.
A COMPLEMENTARY FREEZE‐FRACTURE STUDY OF CHRYSOCHROMULINA CHITON (HAPTOPHYCEAE)
Authors: Neushul M. , Northcote D. H.
Published: January 2018

Complementary freeze‐fracture replicas and high resolution tantalum‐tungsten shadowing have been used in a study of the membanes of the marine alga Chrysochromulina chiton. Membrane particle populations range from 38/100 nm2 in the plastid to 2/100 nm2 in the pyrenoid cap membrane. Membrane asymmetry was evident in all membranes, but was most obvious in those with higher particle numbers. In all complementary replica pairs, particles were always more numerous on protoplasmic fracture faces. Small, particle‐free areas with bordering particles were also seen as recurring membrane features. Complementarity of matching fracture faces was seen for very small background granularity patterns and for large membrane components, but not for particles. Complementarity can also be seen in non‐membranous fracture faces both within and external to the cell, suggesting the presence of polymeric materials in these areas that produce “particles” due to plastic deformation.
STRUCTURE AND DEVELOPMENT OF LEAVES IN CARLUDOVICA PALMATA (CYCLANTHACEAE) WITH REFERENCE TO OTHER CYCLANTHACEAE AND PALMAE
Authors: Wilder George J.
Published: January 2018

The adult leaf of Carludovica palmata consists of a plicate lamina, adaxial hastula, petiole, and sheath. The leaf is unusual in the angiosperms because about two‐thirds of the apical meristem is utilized in its initiation. The adult leaf requires about 4–5 plastochrons to mature. Shortly after its initiation the adult leaf and apical meristem collectively appear pyramid‐shaped and various parts of the mature adult leaf may be traced back to particular portions of the pyramid. Plications develop by differential growth within the lamina, not by splitting of leaf tissue. Quantitative studies indicate that certain regions of the developing adult leaf elongate more rapidly or slowly than other regions depending upon the stage of leaf development. The adult leaf of C. palmata develops differently from those of previously studied palms in various ways. It therefore appears less justifiable to consider the superficial similarity between the adult leaves of various Cyclanthaceae (particularly those of Carludovica sensu strictu) and those of fan palms as evidence of especial affinity between the Cyclanthaceae and Palmae. Juvenile leaves of C. palmata differ from adult leaves both in their mode of origin and appearance at maturity. The juvenile leaf appears homologous to the entire adult leaf.
ULTRASTRUCTURAL DIFFERENTIATION OF THE MÜLLERIAN BODY GLYCOGEN PLASTID OF CECROPIA PELTATA L.
Authors: Rickson Fred R.
Published: January 2018

The developmental ultrastructure of the glycogen plastids produced in Müllerian body cells of Cecropia peltata was studied. Cells of the trichilium, before Müllerian body initiation, possess chloroplasts. Once cell division begins in the initiation of a food body, the choroplasts dedifferentiate to proplastids. As cell division and development proceed the proplastids divide and enlarge so that each cell of the Müllerian body contains 20–30 of these organelles. With maturation of a Müllerian body the proplastids begin to synthesize and store glycogen. Each developing glycogen plastid possesses an inclusion composed of protein and glycogen, and, based on cytochemical evidence, it is suggested that the glycogen synthesizing enzymes are associated with this inclusion.
THE PRIMARY ROOT EPIDERMIS OF PANICUM VIRGATUM L. I. ONTOGENY AND FINE STRUCTURE OF THE EPIDERMAL CYTOPLASMIC INCLUSIONS
Authors: Lewis Robert F. , Crotty William J.
Published: January 2018

The ontogeny of large, globular, epidermal cytoplasmic inclusions (ECI) in P. virgatum roots was studied at the ultrastructural level. These ECI were seen to originate in meristematic cells as small electron translucent vesicles. Subsequently, the ECI, which appeared to be temporary storage sites, were seen to enlarge and increase in density by accumulating masses of a granular matrix as well as some small vesicular inclusions. In the zone of elongation, as the epidermal cells matured, the ECI within each cell gradually fused and the contents were lost. The pattern of the ontogeny of the ECI in the growing epidermal cells was consistent with the presence of cells of different physiologies in the zone of cell elongation of these roots.
A SYSTEMATIC REVIEW OF THE SUBTRIBE LAGASCEINAE (COMPOSITAE, HELIANTHEAE)
Authors: Stuessy Tod F.
Published: January 2018

The subtribe Lagasceinae of the tribe Heliantheae is recognized traditionally to consist of two genera: Lagascea and Coulterella. Although both taxa possess uni‐flowered heads aggregated into synflorescences, they are very different in most other morphological and anatomical respects. The six species of Lagascea that were investigated cytologically are n = 17, whereas the monotypic Coulterella is n = 18 with chromosomes one‐half the size of those of Lagascea. The dissimilarities suggest that the two genera should not be retained in the same subtribe, and that the subtribe Lagasceinae should be abandoned. Lagascea seems to be related most closely to genera of the subtribe Helianthinae, such as Alvordia. Coulterella, on the other hand, seems closest to Flaveria of the tribe Helenieae or Senecioneae.
STUDIES IN THE FLORAL ANATOMY OF POLYGALA (POLYGALACEAE)
Authors: Milby T. H.
Published: January 2018

Flowers of Polygala are irregular, each having three small and two long winglike sepals, three petals, eight stamens, and a bilocular ovary. These flowers have been considered pentamerous, and placentation has been subject to various interpretations. Development and anatomy of flowers of Polygala alba, P. lanceolata, and P. lutea were studied to see if evidence of pentamery and change in placentation could be found. These studies reveal no evidence of vestigial petals or stamens nor of vascular traces to organs that are missing in the three species studied. Neither are there abortive sporangia in the bisporangiate anthers. Observations on development of carpel primordia and on the vascular plan of mature carpels indicate that placentation is fundamentally parietal rather than axile. Speculation is offered as to the derivation of this type of placentation.
THE ORGANIZATION OF THE VASCULAR SYSTEM IN THE STEMS OF THE NYMPHAEACEAE. II. NYMPHAEA SUBGENERA ANECPHYA, LOTOS, AND BRACHYCERAS
Authors: Weidlich W. H.
Published: January 2018

The anatomy and organization of the stem vascular system was analyzed in representative taxa of Nymphaea (subgenera Anecphya, Lotos, and Brachyceras). The stem vascular system consists of a series of concentric axial stem bundles from which traces to lateral organs depart. At the node each leaf is supplied with a median and two lateral leaf traces. At the same level a root trace supplies vascular tissue to adventitious roots borne on the leaf base. Flowers and vegetative buds occupy leaf sites in the genetic spiral and in the parastichies seen on the stem exterior. Certain leaves have flowers related to them spatially and by vascular association. Flowers (and similarly vegetative buds) are vascularized by a peduncle trace that arises from a peduncle fusion bundle located in the pith. The peduncle fusion bundle is formed by the fusion of vascular tissue derived from axial stem bundles that supply traces to certain leaves. The organization of the vascular system in the investigated taxa of Nymphaea is unique to angiosperms but similar to other subgenera of Nymphaea.
THE BALLISTOSPORIC PROTOSTELID GENUS SCHIZOPLASMODIUM
Authors: Olive Lindsay S. , Stoianovitch Carmen
Published: January 2018

The genus Schizoplasmodium is a member of the Protostelia, a primitive subclass of mycetozoans. It has previously been known only from the commonly occurring type species, S. cavostelioides Olive and Stoianovitch. Two additional species of rare occurrence are described here—S. obovatum, found on bark of living trees in Florida and Uganda, and S. sechellarum, found in the Seychelles Islands and Papua New Guinea on old corn and leguminous capsules. All three members of the genus produce reticular plasmodia but lack flagellate cells. The most unusual feature of the group is the production of ballistospores that are discharged from their stalks by the development and explosion of gas bubbles.
RESOURCE ALLOCATION AND REPRODUCTION IN POPULATIONS OF AMPHICARPUM PURSHII (GRAMINEAE)
Authors: McNamara James , Quinn James A.
Published: January 2018

Five New Jersey populations of Amphicarpum purshii (an annual panicoid grass) were investigated as to total allocation of biomass to reproduction and its distribution between aerial chasmogamous and subterranean cleistogamous inflorescences. Germination of both types of seed was documented, for the first time, in not only the field but under three laboratory temperature regimes. Overall, approximately 29 % of the shoot biomass was allocated to reproduction. On a population basis, subterranean inflorescences accounted for 37–100 % of the reproductive biomass, and these seed (5 × heavier but fewer in number) were the source of most surviving seedlings. Subterranean spikelets contained caryopses significantly more frequently than aerial spikelets. The ratio of the number of viable aerial seed to the number of viable subterranean seed increased from 0/4 to 4/2 with recentness and/or frequency of disturbance. As a pioneer species in secondary succession, Amphicarpum purshii produces a larger subterranean propagule, with greater seedling vigor and a higher probability of local reproductive success, and also a smaller aerial propagule in larger numbers with potentially greater genetic variability.
A COMPARISON OF MERISTEMS AND UNEQUAL GROWTH OF INTERNODES IN VINY MONOCOTYLEDONS AND DICOTYLEDONS
Authors: French James C. , Fisher Jack B.
Published: January 2018

The distribution of meristematic activity and cell length in the growing internodes of seven species of dicotyledonous vines and three species of monocotyledonous vines is described. In Schlegelia, Ipomoea, Mucuna, Passiflora, Ficus, Thunbergia alata, Dioscorea, Smilax, and Vanilla the loss of meristematic activity proceeded from the base to the top of the internode. The absence of isolated meristematic regions is typical of the uninterrupted meristem. In Thunbergia grandiflora a small peak of residual meristematic activity is located at the base of the internode, which is typical of the intercalary meristem. The same region of the internode is swollen and functions as a pulvinus. The young internodes of the seven dicotyledonous vines and an additional eight species of monocotyledonous vines with uninterrupted meristems were marked into three segments for growth studies. The upper part of the internode grew more rapidly and for a longer time than the basal part of the internode, except in T. grandiflora. The relative amounts of unequal growth in various species differed widely. Greater growth of the upper region was not correlated with comparable increases in final cell length in the upper region. It is concluded that the uninterrupted meristem is a common feature of shoot extension in many monocotyledons and dicotyledons.
SPORE WALL FORMATION IN THE MYXOMYCETE PHYSARELLA OBLONGA
Authors: Bechtel Donald B.
Published: January 2018

The spore wall of the myxomycete, Physarella oblonga, requires only 1 hr to develop. The spore wall surface ornamentations, the warts, are secreted first, followed by an outer electron‐dense layer and an inner electron‐lucent layer. A measurement analysis was conducted to determine if vesicles were involved in wall elaboration. By comparing spore plasmalemma length to the number of fused vesicles, a semi‐quantitative analysis can be obtained. The determination reveals that very few vesicles are associated with wart and outer wall development. The greatest number of vesicles are associated with inner wall secretion. Plasmalemmasomes are most numerous during outer wall formation and Golgi bodies are observed only during inner wall elaboration. Other organelles do not seem directly involved in wall secretion.
REQUIREMENT OF AN INTERNAL STANDARD FOR MICROSPECTROPHOTOMETRIC MEASUREMENTS OF DNA
Authors: Dhillon Sukhraj S. , Berlyn Graeme P. , Miksche Jerome P.
Published: January 2018

Cytophotometric measurements of DNA quantity per cell from 45 different Pinus rigida trees obtained from 135 slides showed that an internal standard was necessary in order to avoid serious errors. Chicken red blood cells were incorporated on the same slide as the pine cells, permitting the calculation of the actual mass units of DNA per pine nucleus. The use of these units makes the results of different investigations and investigators directly comparable. Staining variation between slides and staining batches was shown to be the reason for the requirement of an internal standard. DNA quantity in Feulgen units varied as much as 2.9 fold between different slides of red blood cells although the actual quantity of DNA is constant at 2.8 picograms per nucleus.
DIFFERENTIAL ENZYME ACTIVITY DURING TRICHOBLAST DIFFERENTIATION IN ELODEA CANADENSIS
Authors: Dosier Larry W. , Riopel J. L.
Published: January 2018

Enzymes active in the developing root epidermis of Elodea canadensis Michx. were demonstrated by histochemical techniques. The future root‐hair‐forming cells (trichoblasts) showed a period of elevated activity more extensive than the one previously reported in trichoblasts of another species for dehydrogenases (glucose‐6‐phosphate, pyruvate, lactate, succinic, isocitrate, glutamate), phosphatases (acid, ATPase, 5‐nucleotidase), cytochrome oxidase, and peroxidase. This elevated activity extended from the time of trichoblast formation up to the point of root hair outgrowth, even for enzymes not previously demonstrated in trichoblasts: alkaline phosphatase, NADH diaphorase, NADPH diaphorase, esterase, and leucine aminopeptidase. Glucose‐6‐phosphatase and aryl sulfatase were not detected. The single exception to this pattern was phosphorylase activity, which intensified only just prior to and during root hair outgrowth. The more generalized activity pattern is considered to indicate the so‐called meristematic character of these cells in terms of both macromolecular synthesis and lack of specialization. It is suggested that specific root hair development begins just prior to initiation, at the point marked by elevated phosphorylase activity.
VASCULAR ANATOMY OF THE NODAL REGION IN POPULUS DELTOIDES BARTR
Authors: Isebrands J. G. , Larson Philip R.
Published: January 2018

The ontogeny of vascular bundles in the nodal region of Populus deltoides Bartr. was examined to understand more thoroughly the structure‐function relation between leaf and stem. Three vascular traces from the stem independently enter each leaf in the nodal region. At the base of each developing leaf a region was observed in which both bundle size and vascular development was reduced; this region was referred to as the constricted zone. The constricted zone was described quantitatively at 13 locations within the nodal region of a leaf at LPI 5 by determining the number of metaxylem vessels and the total metaxylem vessel area in each of the three leaf traces. A plot of these data showed a distinct minimum value for total metaxylem vessel area within the constricted zone of each trace; the location of this minimum value was referred to as the constriction plane. Each vascular bundle within the nodal region is composed of independent subsidiary bundles that originate within the constricted zone. These bundles provide a direct connection between the leaf lamina and the stem. The node was defined anatomically on the basis of the ontogenetic development of the subsidiary bundles. The node began at the initial exit point of the central trace from the vascular cylinder and extended distally to the constriction plane. This definition allowed us to quantify the limits of each node. The origin of the initiating layer and metacambium was also examined within the nodal region. These precursors of the cambium develop continuously and acropetally from the stem into the leaf. The developmental implications of the constricted zone and the metacambium within the nodal region are discussed with respect to wood formation.
GEOGRAPHY OF CLAYTONIA VIRGINICA CYTOTYPES
Authors: Lewis Walter H. , Semple John C.
Published: January 2018

Three widespread ploidy levels have evolved in Claytonia virginica, a diploid represented by n = 8, 7, and 6 races, a triploid primarily by n = 12 and 11, and a tetraploid by n = 16, 15, 14, and other aneutetraploids. In addition, sporadic higher polyploids (5x–24x) occur throughout eastern North America. These data are considered briefly in relation to meiotic behavior, to coexistence of major cytotypes, and to speciation.
AN UNUSUAL EPICUTICULAR WAX ULTRASTRUCTURE ON LEAVES OF PROSOPIS TAMARUGO (LEGUMINOSAE)
Authors: Hull Herbert M. , Bleckmann Charles A.
Published: January 2018

Studies of Prosopis tamarugo Phil. leaflet surfaces by scanning and transmission electron microscopy disclosed an aggregate coating of basic wax structures of various shapes along with large semi‐vertical plates. The basic structures, with some degree of variation, were also present on P. velutina Woot. and on several other Prosopis species which had been previously investigated. However, the plates, about 3 μm in size, were observed only on P. tamarugo. The basic wax structures were first observed on very young leaflets, about 6 h after emergence from the apical bud. The plates appeared after 24 to 72 h. Both plates and basic structures were larger on seedlings grown in a low (20–25%) relative humidity as compared to high (70%) humidity. When grown side‐by‐side in the greenhouse, leaflets of P. tamarugo seedlings were more isolateral in structure than those of P. velutina, suggesting a greater xeromorphic adaptation. The unusual epicuticular configuration described could be a mechanism that enhances the foliar absorption of atmospheric moisture, or at least minimizes cuticular transpiration, thereby aiding survival of this unique tree in its native habitat of northern Chile.
SEASONAL VARIATION OF ISOZYMES IN JUNIPERUS SCOPULORUM: SYSTEMATIC SIGNIFICANCE
Authors: Kelley Walter A. , Adams Robert P.
Published: January 2018

The relationship of seasonal variation in isozymes to systematic studies at the infraspecific level is evaluated. Isozyme variation in peroxidases, esterases, and α‐terpineol dehydrogenases was evaluated monthly for one year in J. scopulorum Sarg. Zymograms of α‐terpineol dehydrogenases showed one nonvariable band. Isoperoxidases varied quantitatively but not qualitatively, this variation being correlated with seasonal growth and dormancy. Isoesterases showed qualitative variation, with two types of esterases being produced. One type showed seasonal variation and a second was nonvariable. The presence of two types of isoesterases may reflect differing physiological roles for each. The esterase results showed that care should be taken during investigations of isozymes at the population level to assure phenological similarity.
NET PRIMARY PRODUCTION AND PHENOLOGY ON A SOUTHERN APPALACHIAN WATERSHED
Authors: Day Frank P. , Monk Carl D.
Published: January 2018

Net primary production (NPP) is an important function of plant communities which has not often been examined seasonally in a forested ecosystem. The major objective of the study was to measure above‐ground NPP seasonally and relate it to phenological activity on a hardwood forest watershed at Coweeta Hydrologic Laboratory, North Carolina. NPP was estimated as the increase in biomass, estimated from regression equations on diameter. Diameter increases were measured by vernier tree bands. Phenological observations were made on bud break, leaf emergence, flowering, mature fruit, leaf senescence, and leaf fall. The species studied intensively were Acer rubrum, Quercus prinus, Carya glabra, Cornus florida, and Liriodendron tulipifera. Liriodendron was found to be the most productive species per individual, but Quercus prinus was the most productive per unit ground area. The total watershed estimate of aboveground NPP was 8,754 kg ha‐1 yr‐1 and included 47.9% leaves, 33.2% wood, 7.8% bark, 4.8% reproductive tissues, 4.2% loss to consumers, and 2.1% twigs. Increases in leaf biomass were most rapid in the spring, but woody tissue production peaked in June and continued through August. Since leaf production peaked in the spring, the plants' photosynthetic machinery was activated early in the growing season to support woody tissue production, which followed the period of rapid leaf growth, and reproductive activity. Flowering occurred during the leaf expansion period except for Acer rubrum, which flowered before leaf emergence. Fruit maturation occurred during late summer to early fall, when there were no additional biomass increases. Acer rubrum was an exception as its fruit matured during the period of leaf expansion.
SEASONAL NUTRIENT DYNAMICS IN THE VEGETATION ON A SOUTHERN APPALACHIAN WATERSHED
Authors: Day Frank P. , Monk Carl D.
Published: January 2018

Nutrient dynamics in vegetation play an important role in determining the circulation and storage of nutrients in an ecosystem. The major objectives of this study were to estimate the plant nutrient pools (K, Ca, Mg, and Na) on a hardwood forest watershed at Coweeta Hydrologic Laboratory, North Carolina, on a seasonal basis and to relate any observed trends to seasonal productivity and phenology. Late‐summer nutrient standing crops in the vegetation were calculated to be 551 kg/ha Ca, 233 kg/ha K, 48 kg/ha Mg, and 48 kg/ha Na. Nitrogen, P, and K concentrations in the leaves decreased seasonally, whereas Ca concentrations increased and Mg and Na concentrations remained relatively constant. Nutrient concentrations in the woody portion of the plants remained relatively constant. Standing crops of all nutrients increased seasonally with slight decreases of N and K in the leaves in the fall. Major conclusions of the study were 1) individual species and different plant components have nutrient storage‐pool turnover times ranging from one year to several hundred years. Canopy species are important in long and short term nutrient cycles; nutrient‐rich understory species such as Cornus florida are important in the annual cycle; and evergreen species are important in cycles of intermediate length because of nutrient storage in their perennial leaves. 2) Even though most of the annual nutrient uptake is recycled the same season (92%, 79%, 93% and 68% of K, Ca, Mg, and Na uptake, respectively), the total accumulation of nutrients is considerable in a mature forest stand.
CENTRIFUGAL STAMEN INITIATION IN PHYTELEPHANTOID PALMS
Authors: Uhl Natalie W. , Moore Harold E.
Published: January 2018

The phytelephantoid group, considered very highly specialized among the 15 major groups of palms, includes only three dioecious genera which are distinguished by multipartite flowers. Staminate flowers of these genera have from 120 to over 900 stamens, the largest number known in palms. Developmental material shows centrifugal inception of stamens in Palandra and Phytelephas, and the course of the trunk bundles indicates centrifugal initiation of stamens in Ammandra. Stamens of all three genera are supplied by large trunk bundles that develop acropetally following the different centrifugal expansion of the floral apex in each genus. Branches of the trunk bundles form later to supply stamen primordia as they develop. Polyandric androecia occur in ten of the major groups of palms. Other multistaminate genera show expansion and change in shape of the floral apex before stamen initiation. Centrifugal development appears to represent a different method of expansion of the floral apex to accommodate increase in stamen number in this group. Centrifugal inception of stamens in monocotyledons has previously been established only for two genera of Butomaceae.
CHLOROPHYLL LEVELS AND LEAF ULTRASTRUCTURE AS ECOTYPIC CHARACTERS IN XANTHIUM STRUMARIUM L.
Authors: Abdulrahman Farag S. , Winstead Joe E.
Published: January 2018

Comparison of six different populations of Xanthium strumarium grown under controlled laboratory conditions revealed a general pattern of greater chlorophyll levels with increase in latitude of origin. Indications of ultrastructural differences were found, with plants containing greater chlorophyll levels having more chloroplasts with greater membrane development compared to plants of this species from more southern or lower latitude habitats.
ADHERENCE OF AGROBACTERIA TO MOSS PROTONEMA AND GAMETOPHORES VIEWED BY SCANNING ELECTRON MICROSCOPY
Authors: Spiess Luretta D. , Turner Jocelyn C. , Mahlberg Paul G. , Lippincott Barbara B. , Lippincott James A.
Published: January 2018

The attachment of certain Agrobacterium species to moss protonema was examined by scanning electron microscopy. The bacteria cultured with the moss adhered to the protonemal filaments of Pylaisiella selwynii and Funaria hygrometrica throughout the fixation and washing procedure prior to examination. The number of bacteria adhering per unit length of filament did not correlate with the ability of four species (A. tumefaciens, A. rubi, A. rhizogenes, A. radiobacter) to induce gametophore formation in P. selwynii. Little difference was found between the number of A. tumefaciens on P. selwynii or on F. hygrometrica, and although this bacterial species induced gametophores on P. selwynii, it had no effect on F. hygrometrica. A. rhizogenes, which is capable of inducing rhizoid formation on both P. selwynii and F. hygrometrica without physical attachment, did associate with filaments of both mosses. Larger numbers of A. tumefaciens and A. rubi, which induce gametophores or callus, were associated with the spore and germ tube of P. selwynii than were A. rhizogenes or A. radiobacter which do not initiate these changes. These results suggest that the germ tube may constitute the site where effective attachment occurs. The number of A. tumefaciens adhering to P. selwynii was greatest at 2–6 h after addition and then decreased by 26 h, raising the possibility that some bacteria lyse following attachment. None of the bacteria adhered to the gametophore walls of either moss, indicating that a change in cell wall surface may occur. The four species of Agrobacterium differed in their orientation when adhering to the moss. These results suggest that the process of bacterial adherence to higher plant cells in Agrobacterium infection is similar to that which we observe in mosses and which leads to developmental changes.
THE GROWTH OF SELECTED DESMID (DESMIDIALES, CHLOROPHYTA) TAXA AT DIFFERENT CALCIUM AND PH LEVELS
Authors: Gough Stephen B.
Published: January 2018

The growth of clonal isolates of Closterium moniliferum and Cosmarium granatum from hard waters and Triploceras gracile from an acid bog was examined at two different levels of calcium and pH. Low pH and low calcium favored the growth of Triploceras, whereas Closterium grew equally well at both calcium levels but preferred the higher pH. Cosmarium favored both high pH and a high calcium concentration. Each taxon was affected by an interaction of the parameters on the growth rates. The results from studies on these taxa do not completely support the generalizations generated by previous investigations on the chemical factors affecting the growth and distribution of desmids; the controlling influences may, therefore, involve a complex interaction of factors which are unique for individual taxa or groups of taxa.
MORPHOLOGICAL STUDIES IN SORDARIA FIMICOLA AND GELASINOSPORA LONGISPORA
Authors: Mai Shing H.
Published: January 2018

Perithecium development in Sordaria, the type genus of the Sordariaceae, is similar to that reported in other genera of this family. Features that characterize the Sordariaceae include the differentiation of the hyphal envelope that surrounds the ascogonium into peripheral wall layers and a pseudoparenchymatous centrum. Broad paraphyses composed of delicate, multinucleate cells arise from the cells of the centrum and completely fill the perithecium, crushing the remaining pseudoparenchymatous cells against the perithecial wall. Sordaria fimicola differs from other species of Sordariaceae studied in the aggregation of the ascogenous cells to form a placenta‐like mass in the base of the centrum. Consequently, the asci arise in a cluster rather than in a uniform wall layer. Incomplete observations on Gelasinospora longispora indicate that its development is typically sordariaceous.