bluuebunny/crossref_metadata_2025 huggingface dataset:
THE DEVELOPMENT OF SPATIAL PATTERN IN CLONES OF AN AQUATIC PLANT, EICHHORNIA CRASSIPES SOLMS
Authors: Watson Maxine A. , Cook Craig S.
Published: January 2018

The spatial geometry of clonal growth of Eichhornia crassipes, a plant which increases in number by the vegetative production of stolon offshoots (or ramets), was assessed by the use of a vector analysis. Growth of water hyacinth clones was found to be asymmetric, asymmetry increasing with time. The direction of asymmetry was independent of either population density or the position of nearest neighbors. The analysis revealed the importance of geometric relationships within the parental growth axis for determining patterns of clonal spread. Meristem growth and differentiation appear to be controlled so as to maximize clonal growth rate. This contrasts with the patterns observed in rhizomatous terrestrial species in which the control of meristem growth and differentiation appears to result in efficient use of space at the expense of greater increase in clonal size.
A SURVEY FOR 1,3,6,7‐TETRAHYDROXY‐C‐GLYCOSYLXANTHONES EMPHASIZING THE “PRIMITIVE” LEPTOSPORANGIATE FERNS AND THEIR ALLIES
Authors: Wallace James W. , Markham Kenneth R. , Giannasi David E. , Mickel John T. , Yopp Don L. , Gomez Luis D. , Pittillo J. Dan , Soeder Robert
Published: January 2018

A survey for 1,3,6,7‐tetrahydroxy‐C‐glycosylxanthones of representative species within the primitive vascular plants, emphasizing the leptosporangiate ferns, has indicated a limited distribution of these compounds within three leptosporangiate families: Hymenophyllaceae, Aspleniaceae and Marsileaceae. In the Hymenophyllaceae the distribution of these compounds appears to be a useful criterion for segregating species of Mecodium from other species of Hymenophyllum (sensu lato) and suggests that the tubulate vs. the valvate indusial condition may not be an ideal character for separating all species of Hymenophyllum (s.l.) from those of Trichomanes (s.l.). These compounds appear useful for delimiting several species of Elaphoglossum section Pachyglossa and support a relationship among the Aspleniaceae, Athyriaceae, and Elaphoglossaceae. Their presence in Marsilea also raises questions as to the origin of this group of plants.
THE TRANSMITTING TRACT IN GLADIOLUS. I. THE STIGMA AND THE POLLEN‐STIGMA INTERACTION
Authors: Ameele Randall J.
Published: January 2018

The stigma papillae in Gladiolus are of the “dry” type and are highly vacuolated cells with an organelle‐rich peripheral cytoplasm. The cell wall of each papilla is overlain by a distinctive cuticle possessing an irregularly scalloped inner margin. Between the cell wall and cuticle is a layer of amorphous sub‐cuticular material. Lipids are detected on the papilla surface. A pollen grain will hydrate and germinate only on a papilla and not on any other (non‐papillate) portion of the stigma. The pollen tube penetrates the papilla cuticle, which is forced away from the papilla cell wall by sub‐cuticular pollen tube growth. As the cuticle lifts away, the sub‐cuticular material disperses. At the base of the papilla, the pollen tube grows onto the adaxial non‐papillate surface of the stigma lobe. At this site, the cuticle has been lifted away from the underlying cells by release of a mucilaginous substance from the latter, and the pollen tube grows within this substance beneath the detached cuticle. The cytological features of Gladiolus papillae are compared with other stigma papillae described in the literature. Also, a review of the literature, as well as some of the findings of the present study, suggest that certain prevalent interpretations of dry stigma structure and function may be open to question.
DECOMPOSITION DYNAMICS OF SPARTINA ALTERNIFLORA AND SPARTINA PATENS IN A NEW JERSEY SALT MARSH
Authors: Frasco Barbara A. , Good Ralph E.
Published: January 2018

Decomposition dynamics of two salt marsh species, Spartina alterniflora tall (SAT) form and Spartina patens (SP), were investigated at Mud Cove, near Manahawkin, Ocean County, New Jersey. Decomposition rates were determined monthly over 371 days by measuring the amount of material lost from plastic net litter bags. Litter bags containing SP material were placed in both SP and SAT vegetation zones; litter bags containing SAT material were also placed in both of these zones. The material was analyzed for ash content, total carbon, Kjeldahl nitrogen, caloric content, fat, and crude fiber.

Final weight loss values were as follows: SAT in SAT zone 72.4%, SP in SAT zone 56.9%, SAT in SP zone 46.7%, and SP in SP zone 26.4%. When SAT and SP material were placed in the same location (SAT or SP sites), the SAT material decomposed at a greater rate. If the same vegetation type (SAT or SP) were placed in both SAT and SP locations, the material at the SAT location decomposed at a greater rate than similar material in the SP location. The results indicate that while environmental characteristics (e.g., flooding) at a site influence the rate at which these two species will decompose, Spartina patens is inherently more resistant to decomposition.
EFFECTS OF H ION ON ECOLOGICAL SYSTEMS: EFFECTS ON HERBACEOUS BIOMASS, MINERALIZATION, NITRIFIERS AND NITRIFICATION IN A FOREST COMMUNITY
Authors: Lodhi M. A. K.
Published: January 2018

The effects of H ion were studied by lowering the soil pH in a deciduous forest. Increased H+ burden significantly reduced the dry mass of herbaceous vegetation. Increased H+ significantly mobilized Ca (226%) and Mg (244%) to the deeper soil profile, thus reducing uptake of those nutrients by intact vegetation. Moreover, the low pH also had a drastic impact on nitrifiers and nitrification. The 70% reduction in NO‐3‐N was directly related to the reduction in numbers of Nitrosomonas (91%) and Nitrobacter (100%). Ammonium N also declined under H+ stress, indicating a reduction in N‐mineralization process. It was hypothesized that increased H+ stress in deciduous forests may deplete major nutrients, mobilize micronutrients, reduce soil microbial populations and decrease plant biomass. Thus a deciduous forest may evolve into a nutrient‐poor soil ecosystem and may shift toward a “semi‐podzol ecosystem.”
A MORPHOMETRIC STUDY OF THE ULTRASTRUCTURE OF ECHINOCEREUS ENGELMANNII (CACTACEAE). IV. LEAF AND SPINE PRIMORDIA
Authors: Mauseth James D.
Published: January 2018

A stereological morphometric study of leaf primordia (P1 and P2) of Echinocereus engelmannii indicated that primordia are significantly different ultrastructurally from the shoot apical meristem tissues (tunica and peripheral zone) that produce the primordia. Leaf initiation involves readjustments of rates of synthesis and growth of cytoplasm, vacuoles, mitochondria, chloroplasts, and dictyosomes, such that leaf initiation must be a complex process in which different cell components are affected individually. Furthermore, leaf primordia are ultrastructurally distinct from spine primordia. Leaf and spine primordia as young as these are not yet irrevocably determined, thus different types of primordia, from the time of their inception and before their determination, have distinctly unique metabolisms; primordia are not merely generalized, uncommitted outgrowths whose developmental fate is set at some time later than inception.
EFFECTS OF VARIATION IN FLORAL MORPHOLOGY ON POLLINATION MECHANISMS IN ASCLEPIAS TUBEROSA L., BUTTERFLYWEED (ASCLEPIADACEAE)
Authors: Beare Michael H. , Perkins W. Ethen
Published: January 2018

Field observations revealed the presence of fruit‐producing (fruiting) and non‐fruit‐producing (non‐fruiting) plants in two south central Oklahoma populations ofAsclepias tuberosaL. Comparative measurements of floral characteristics between fruiting and non‐fruiting plants indicated that fruiting plants have significantly larger alar fissure widths and a greater percentage of intact pollinaria. The smaller alar fissure width on flowers of non‐fruiting plants apparently reduces the probability of successful pollinia insertions in these plants. Greater numbers of observed pollinia insertions into fruiting‐plant fissures appear to be the result of the increased likelihood that pollinia, which are significantly narrower than the fissures of fruiting plants, will be inserted into fruiting‐plant fissures than those of non‐fruiting plants. Apparently non‐fruiting plants act primarily as pollinia donors while fruiting plants act primarily as pollinia recipients. These characteristics of butterflyweed tend to promote a dimorphic, allogamous type of pollination.
DISPLACEMENT OF ANDROPOGON SCOPARIUS ON THE NEW JERSEY PIEDMONT BY THE SUCCESSIONAL SHRUB MYRICA PENSYLVANICA
Authors: Collins Beverly S. , Quinn James A.
Published: January 2018

Andropogon scoparius, a perennial grass found in old fields on the New Jersey Piedmont, can be invaded and displaced by a nitrogen‐fixing shrub, Myrica pensylvanica. The progression of Andropogon displacement was followed over a season, and possible contributing mechanisms (shading, allelopathy, physical effects of Myrica litter) were tested through field and greenhouse experiments. In the field, Andropogon seedling growth was inhibited beneath Myrica clumps, and mature plant living crown area was reduced. In the greenhouse, Andropogon seedling growth was reduced significantly in pots with mature Myrica. Both seedling and mature growth of Andropogon were reduced under shaded conditions. No inhibitory physical effects of Myrica litter on Andropogon seed germination or mature plant growth were found; however, there may ba allelopathic effects of Myrica litter leachate on Andropogon seedlings growing under shade or within grass litter, and on mature Andropogon in shaded conditions. Andropogon displacement appears to be the result of a complex interaction of Myrica shade, allelochemic, and competitive effects, rather than being attributable to any single mechanism.
BIOMASS AND NET PRIMARY PRODUCTION OF PROSOPIS GLANDULOSA (FABACEAE) IN THE SONORAN DESERT OF CALIFORNIA
Authors: Sharifi M. Rasoul , Nilsen Erik T. , Rundel Philip W.
Published: January 2018

Prosopis glandulosa var. torreyana accounts for nearly 90% of the total plant cover in a mesquite woodland community near Harper's Well along the southern margin of the Salton Sea in the Sonoran Desert of California. Total above‐ground biomass in ten individuals studied in detail ranged from 43–760 kg per plant and 1.9–8.5 kg m‐2 canopy area. Stand biomass ranged locally from a high of 23,000 kg ha‐1 near the wash to 3,500 kg ha‐1 in the fringe of this mesquite stand. Net above‐ground primary production for 1980 had a mean of 2.2 kg m‐2 canopy for shrub forms and 5.3 kg m‐2 canopy for tree forms. Mean Prosopis stand production for 1980 was 3,650 kg ha‐1, an extremely high value for desert communities. This level of production is particularly high in relation to the low mean annual precipitation of approximately 70 mm. New woody tissues in trunk and branches accounted for 51.5% of the allocation of productivity in Prosopis, a remarkably high woody allocation for a desert plant. Only 33.6% of net primary production was allocated to leaves.
FLAVONOID CHEMISTRY AND SYSTEMATICS OF TITHONIA (COMPOSITAE)
Authors: La Duke John C.
Published: January 2018

Twenty‐four flavonoid compounds, including chalcones and aurones, are reported from 13 taxa of Tithonia. Pedunculin (4′, 6, 7‐trimethoxy, 5, 8‐dihydroxyflavone), also is characterized. The distribution of these compounds is compared to the existing classification of the genus based primarily on morphological data. By comparison with the previously proposed phylogeny of the genus, the evolution of the flavonoid system may be elucidated. It is proposed that the ancestral stock of Tithonia had flavonols, di‐ and tri‐methoxyflavones, and 6‐methoxyflavones. From this ancestral stock, a number of trends have occured in derivative taxa. These trends are: 1) a maintenance of a diversity of compounds in several evolutionary lines, 2) a reduction in the number of methoxyl substitutions, and 3) the elaboration of 5‐deoxyflavones and flavonols.
FLORAL AND FRUIT MORPHOLOGY OF NEPENTHES LOWII AND N. VILLOSA, MONTANE CARNIVORES OF BORNEO
Authors: Kaul Robert B.
Published: January 2018

Floral structure and function and some aspects of development are illustrated for Nepenthes lowii and N. villosa. The floral nectar glands are similar in structure to nectar glands and digestive glands of pitchers. The stamens are fused and form an anther‐head, but identities of individual stamens are mostly retained. Placentation is laminar. Evidence of entomophily is presented. Only 4.5% of the seeds in the sample bore embryos, and fertile seeds lack endosperm. There is need of field observations on pollination.
DIAGNOSTIC ANATOMICAL CHARACTERS IN THE PLEUROTHALLIDINAE (ORCHIDACEAE)
Authors: Pridgeon Alec M.
Published: January 2018

An anatomical survey of 200 species in 22 genera of subtribe Pleurothallidinae (Orchidaceae) indicates which vegetative characters are of diagnostic value and at what taxonomic level. Most systematically useful characters are associated with the leaf, and include features of trichomes, cuticle, epidermis, hypodermis, spiral thickenings, and number of vein series. The secondary stem is of limited usefulness at higher levels. Number of velamen layers and protoxylem poles in the root may be reliable taxonomic indicators with certain limitations and precautions. The established subtribal phylogenetic trends of reduction in number of pollinia and specialization of the perianth may be correlated with particular anatomical trends, which are either reductionary also or involve specializations directly related to the water relations of the epiphytic habit.
CYTOEMBRYOLOGY OF ALLIUM TEXTILE NELS. & MACBR.
Authors: Khaleel Tasneem F. , Mitchell Becky B.
Published: January 2018

Root tip mitosis, meiosis, sporogeneses, and the development of gametophytes are described for eight populations of Allium textile Nels. & Macbr., native to Montana. The basic chromosome number is n = 7, with tetraploids being predominant. Of the eight populations studied, only one was composed entirely of diploids (2n = 14). Meiosis is generally normal with bivalents and tetravalents formed during the process. Laggard chromosomes leading to the formation of micronuclei are frequently observed during microsporogeny.

The anther wall is five‐layered and its development corresponds to the Monocotyledonous type. The tapetum is glandular and its cells remain uninucleate throughout microsporogeny. The adjacent anther locules coalesce before dehiscence. Pollen grains are shed at the three‐celled stage. A stomium is organized.

Ovules are anatropous, tenuinucellar and bitegminal. The archesporial cell develops directly into a megasporocyte. Development of the female gametophyte is bisporic and corresponds to the Allium type. These observations support Traub's classification (1975) on Allium.
GERMINATION AND GROWTH INHIBITORS IN GUAYULE (PARTHENIUM ARGENTATUM GRAY) CHAFF AND THEIR POSSIBLE INFLUENCE IN SEED DORMANCY
Authors: Naqvi Himayat H. , Hanson George P.
Published: January 2018

Guayule (Parthenium argentatum Gray) is a rubber‐producing plant native to the semi‐arid region of north central Mexico and southwestern Texas. As a member of the family Asteraceae, the seed dispersal unit in guayule is comprised of an achene enclosed by two staminate florets and a bract. The seeds in this condition are dormant and need special treatment in order to germinate. Threshing, prolonged washing, and/or chemical treatments prove effective in improving the germination. Experiments showed that chaff influenced germination and seedling emergence. Bioassays of aqueous extracts of guayule chaff and the seed coat showed a significant inhibition of germination and radicle growth of guayule, lettuce, and tomato seeds. High‐performance liquid chromatography enabled the identification of at least seven phenolic acids from guayule chaff extract. These, in order of decreasing concentrations, included p‐hydroxybenzoic, protocatechuic, p‐coumaric, ferulic, benzoic, vanillic, and cinnamic acids. All of them are well‐known germination and growth inhibitors, and seem to play an important role in the dormancy of guayule seed.
POLLINATION BIOLOGY, SELF‐INCOMPATIBILITY, AND STERILITY IN IPOMOEA PANDURATA (L.) G. F. W. MEYER (CONVOLVULACEAE)
Authors: Stucky Jon M. , Beckmann Robert L.
Published: January 2018

Ipomoea pandurata rarely produces seed. Sporophytic self‐incompatibility is a secondary factor contributing to the reduced seed production because the principal pollinators, Bombus pennsylvanicus (Apidae) and Melitoma taurea (Anthophoridae), effect cross‐pollination in most populations. Sterility, expressed as pollen tube failure in the style and as a sterility mechanism in the ovary, is the primary factor accounting for reduced seed production. It is difficult to reconcile the extensive geographical distribution of I. pandurata with this sterility.
MORPHOLOGICAL SPECIALIZATION AND ATTACHMENT SUCCESS IN TWO TWINING LIANAS
Authors: Peñalosa Javier
Published: January 2018

The success rates of attachment of two twining lianas, Ipomoea phillomega (Vell.) House (Convolvulaceae) and Marsdenia laxiflora Donn. Sm. (Asclepiadaceae), were compared. Ipomoea phillomega, a liana with relatively unspecialized shoot architecture, was found to have a lower success rate than M. laxiflora, a liana with specialized photosynthetic and twining shoots. The relatively lower success rate of I. phillomega is due to its reduced ability to remain attached to very thin supports (<7 mm in diameter).
IN VITRO CULTURE OF GRAIN AND VEGETABLE AMARANTHS (AMARANTHUS SPP.)
Authors: Flores Hector E. , Thier Audrey , Galston Arthur W.
Published: January 2018

We have developed in vitro culture systems for both “grain” and “vegetable” species of the genus Amaranthus. Leaf discs and hypocotyl segments from 2‐ to 3‐wk‐old seedlings of A. hypochondriacus, A. cruentus, and A. tricolor were cultured in B5 and MS media supplemented with 2,4‐dichlorophenoxyacetic acid, α‐naphthaleneacetic acid, benzyladenine and zeatin in various combinations. Rapidly growing callus and abnormal roots formed on leaf discs of A. hypochondriacus and A. cruentus in the presence of 0.1‐1.0 mg/l 2,4‐D. At higher levels (1.0‐10.0 mg/l) of 2,4‐D, embryo‐like structures arose from the surface and veins of the leaf discs. Shoots formed on hypocotyl‐derived callus of both grain species in B5 medium + 0.1 mg/l NAA and 0.1‐1.0 mg/l zeatin. Lower ratios of zeatin/NAA stimulated root formation from hypocotyl segments. Viable mesophyll protoplasts were isolated from primary leaves of all three species, with an enzyme solution of 1% Cellulysin and 0.05% Pectolyase Y‐23, producing a yield of more than 106 protoplasts/g fresh weight.
POLLEN MORPHOLOGY OF THE DILLENIACEAE AND ACTINIDIACEAE
Authors: Dickison William C. , Nowicke Joan W. , Skvarla John J.
Published: January 2018

Pollen of 53 species of Dilleniaceae and Actinidiaceae was examined by light microscopy, scanning electron microscopy, and a selected group in transmission electron microscopy. Dilleniaceae pollen ranges from tricolpate, tricolporate, tetracolpate, and incipiently inaperturate. Tricolpate types occur only among the Old World subfamily Dillenioideae and the compound aperturate (3‐colporate) condition is restricted to the subfamily Tetraceroideae. Within the Dilleniaceae the tricolpate pollen type with elongated apertures is considered primitive, having given rise to the 3‐colporate and 4‐colpate conditions. The striking pollen dimorphism in the Neotropical species of Tetracera, all of which are androdioecious, is documented; however, in contrast to previous reports, pollen from bisexual flowers appears to be incipiently inaperturate and not pantoporate. The inaperturate condition is interpretated as an early stage in the evolution of outcrossing. Pollen morphology does not support a close relationship between Dilleniaceae and Actinidiaceae. Pollen morphological differences that can be noted between these families are: tectum complete and predominantly psilate or psilate‐granular in Actinidiaceae, tectum incomplete, punctate to reticulate in Dilleniaceae; an equatorial bridge of ektexine over the endoaperture usually present in Actinidiaceae, absent in Dilleniaceae; columellae reduced in Actinidiaceae, columellae usually well‐developed in Dilleniaceae. Pollen morphology does not argue against a close relationship between Actinidiaceae and Theaceae.
STUDIES ON THE LEAF OF AMARANTHUS RETROFLEXUS (AMARANTHACEAE***): MORPHOLOGY AND ANATOMY
Authors: Fisher David G. , Evert Ray F.
Published: January 2018

The leaf of Amaranthus retroflexus L. was examined with the light microscope to determine its vasculature and the spatial relationship of the vascular bundles to the mesophyll. Seven leaf traces enter the petiole at the node and form an arc that continues acropetally in the petiole as an anastomosing system of vascular bundles. Upon entering the lamina, the arc of bundles gradually closes and forms a ring of anastomosing bundles that constitutes the primary vein, or midvein, of the leaf. As the midvein progresses acropetally, branches of the bundles nearest the lamina diverge outward and continue as secondary veins toward the margin on either side of the lamina. Along its course the midvein undergoes a gradual reduction in number of bundles until only one remains as it approaches the leaf tip. Tertiary veins arise from the secondaries, and minor veins commonly arise from all orders of major veins, as well as from other minor veins. All of the major veins are associated with rib tissue, although the ends of the tertiaries may resemble minor veins, which are completely encircled by chlorenchymatic bundle sheaths and mesophyll cells that radiate out from the sheaths. A specialized minor vein, the fimbrial vein, occurs just inside the margin of the leaf. Most of the mesophyll cells—the so‐called “Kranz mesophyll cells”—are in direct contact with the bundle sheaths, but some—the so‐called “nonKranz mesophyll cells”—lack such contact. Non‐Kranz mesophyll cells are especially prominent where they form a network of mostly horizontally oriented cells just above the lower epidermis. Guard cells of both the upper and lower epidermis are spatially associated with nonKranz mesophyll cells.
DEMOGRAPHIC ASPECTS OF FLOWER AND FRUIT PRODUCTION IN BEAN PLANTS, PHASEOLUS VULGARIS L.
Authors: Doust Jon Lovett , Eaton G. W.
Published: January 2018

In this paper we assess the relative contributions to total pod yield of cohorts of flowers of known age. Bean plant (Phaseolus vulgaris L.) growth was monitored and 'births' of individual flowers were recorded and their fates followed. For every cohort of flowers an array of yield measures was calculated, including the mean and total cohort dry weight of fruits, and the numbers of viable and aborted seeds and completely undeveloped ovules. When mature, pods were removed from half of the plants. Plants whose mature pods were removed produced significantly greater numbers of flowers, ovules and viable seeds and a greater total weight of pods than did untreated plants. However, the proportion of ovules giving rise to viable seeds and to aborted seeds and undeveloped ovules was the same in plants of both groups. Approximately 50% of ovules of marketable pods, in all plants, yielded viable seeds.

The 12 cohorts of flowers contributed markedly different amounts to plant yield. Early and later cohorts contributed much less than did middle cohorts in terms of marketable pod dry weight and numbers of fully developed seeds, aborted seeds, and undeveloped ovules. Peak productivity was therefore obtained from the middle phase of flowering in these annual bean plants. The lower pod yield of later cohorts is interpreted as a result of competition for limited resources between maturing pods and new flowers.

We consider possible causes for the various fates of flowers and ovules and discuss flowers as plant modules suitable for demographic examination.
OBSERVATIONS ON THE MICROBODIES IN THE GENUS TILLANDSIA (BROMELIACEAE)
Authors: Brighigna Luigi , Fiordi Ambretta Cecchi , Palandri Maria R.
Published: January 2018

Organelles morphologically similar to microbodies have been found in several tissues of atmospheric species of Tillandsia from different habitats. The presence of catalase was demonstrated by the DAB reaction thus confirming the microbody nature of these organelles. They are a feature of the Tillandsia species with normal photosynthetic carbon fixation and with CAM. Their size is consistently small.

The nucleoid observed in the microbodies shows a characteristic morphology which has not been reported before within other plant microbodies. This nucleoid is composed of minute tubular structures, for which the authors here propose a three‐dimensional arrangement.
CENIZERO TREE (LEGUMINOSAE: PITHECELLOBIUM SAMAN) DELAYED FRUIT DEVELOPMENT IN COSTA RICAN DECIDUOUS FORESTS
Authors: Janzen D. H.
Published: January 2018

Pithecellobium saman (Leguminosae: cenízero) is one of several species of Costa Rican deciduous forest large trees that flower at the end of the dry season and then bear dormant tiny fruits through the following rainy season, to then abruptly enlarge and mature them during the first third of the next year's dry season. I postulate that this pattern of fruit development in P. saman minimizes the duration of exposure of immature seeds to parrot and insect seed predators, increases the tree's flexibility in the use of photosynthates accumulated for later fruit maturation, increases resource storage costs, and decreases the photosynthetic contribution that fruit and immature seeds can make to the parent tree's resource budget. These consequences imply that the fruiting phenology of P. saman, like that of other trees, is evolutionarily determined by its interactions with the habitat as well as by internal physiological factors.
PRIMORDIAL LEAF AND PHYTOHORMONE EFFECTS ON EXCISED SHOOT APICAL MERISTEMS OF COLEUS BLUMEI BENTH.
Authors: Smith Roberta H. , Murashige Toshio
Published: January 2018

Coleus blumei Benth. apical meristems and apical meristems +1, +2, +3 primordial leaf pairs were cultured to examine phytohormone influences on development and correlative effects of developing primordial leaves on in vitro responses. The meristem with no phytohormones or low levels of IAA could not develop in vitro. At least 0.1 mg/l IAA and optimumly 1‐2 mg/l IAA were required for development into complete plants. IAA from 0.1 to 3 mg/l also resulted in root development with no apparent leaf or shoot formation. Levels of IAA higher than 3 mg/l were inhibitory to development. Kinetin, as a substitute for naturally occurring cytokinins, alone (0.0003 to 3 mg/l) resulted in development of rosettes of leaves. In the presence of IAA (***1 mg/l) and kinetin (0.003 mg/l) plants, rosettes, individual leaves with roots, and roots developed from isolated meristems. Glutamine and adenine sulfate both appeared inhibitory to meristem development. With +1, +2, +3 developing primordial leaf pairs left attached to the apical dome, three pairs were required for plant formation in the absence of phytohormones. In the presence of IAA, two pairs of primordial leaves resulted in plant formation; whereas, with IAA and low levels of kinetin one pair of primordial leaves was enough. Higher levels of kinetin were inhibitory to plant development with primordial leaves present. ABA appeared to be inhibitory to development of meristems and meristems +1, +3 primordial leaves at low concentrations and resulted in death at ***1 mg/l. Developing primordial leaves appear to supply the apical meristem with a balance of phytohormones during growth. Meristem development into a plant first involved formation of leaf primordia. Establishment of a bipolar axis with root formation followed.
STUDIES ON THE LEAF OF AMARANTHUS RETROFLEXUS (AMARANTHACEAE): QUANTITATIVE ASPECTS, AND SOLUTE CONCENTRATION IN THE PHLOEM
Authors: Fisher David G. , Evert Ray F.
Published: January 2018

The vascular system of the leaf of Amaranthus retroflexus L. was examined quantitatively, and plasmolytic studies were carried out on it to determine the solute concentration in cells of the phloem at various locations in the leaf. The proportion of phloem occupied by sieve tubes varies considerably with vein size and leaf size. Collectively, the cross‐sectional area of sieve tubes of all tributaries at their points of entry into either a secondary or midvein far exceeds the total cross‐sectional area of sieve tubes at the bases of those major veins. In addition, the total volume of sieve tubes in the “catchment area” of a secondary vein is much greater than total sieve‐tube volume of the secondary vein itself. The plasmolytic studies revealed the presence of positive concentration gradients in the sieve tubes of the lamina from the minor veins and tips of the secondaries to the bases of the secondaries and from the tip to the base of the midvein. The C50 (the estimated mannitol concentration plasmolyzing, on the average, 50% of the sieve‐tube members) was 1.5 m for minor veins and tips of secondary veins and 1.1 m for the bases of secondaries; 1.3 m for the tip of the midvein and 0.6‐0.7 m for the midvein in the basal third of the lamina.
INFLORESCENCE AND FLOWER DEVELOPMENT IN THE PIPERACEAE III. FLORAL ONTOGENY OF PIPER
Authors: Tucker Shirley C.
Published: January 2018

Floral development in Piper was compared between four‐staminate species (P. aduncum and P. marginatum) and six‐staminate species (P. amalago). All Piper species have a syncarpous gynoecium composed of three or four carpels. The floral apex is initiated by a periclinal division in the subsurface layer in the axil of a bract 40‐55 μm high; initiation of the bracts occurs separately and considerably earlier. The floral primordium widens and the first pair of stamens are initiated at either side. The median anterior stamen forms next, and the median posterior later. This sequence is common to all species studied. In the six‐staminate P. amalago, the last two stamens form simultaneously in lateral‐anterior positions. The stamens hence arise as pairs, and symmetry is bilateral or dorsiventral. The three or four carpels arise simultaneously; they are soon elevated on a gynoecial ring by growth of the receptacle below the level of attachment of the carpels to produce a syncarpous gynoecium. The floral apex lastly produces the solitary basal ovule and is used up in its formation.
DEVELOPMENT, STRUCTURE AND FUNCTION OF SUBPALISADE CELLS IN WATER IMPERMEABLE SIDA SPINOSA SEEDS
Authors: Egley G. H. , Paul R. N.
Published: January 2018

Newly matured prickly sida (Sida spinosa) seeds were hard, but afterripening, heat or pressure permitted water entry solely via a predefined region of the chalazal area. In this region, the raising of a “blister” formed by separation of the palisade of the seed coat from underlying tissues preceeded measurable water uptake by prickly sida seeds. A single subpalisade layer, unique to the region beneath the blister, was involved in the sequence of events in seed water uptake. The lateral walls of subpalisade cells invariably broke near the palisade border and cell contents were extruded onto the surface. This report describes the cytological development of the subpalisade layer from 1‐21 days post anthesis. Cells beneath the potential “blister” near the chalazal slit developed into columnar subpalisades and cells beneath the subpalisades or beyond the margins of the potential blister, developed into oval, thick‐walled chalazal cap cells. By 6‐10 days, distinct features of the subpalisades included: 1) thin portions in lateral walls due to lack of secondary wall depositions at the palisade border; 2) progressive accumulation of fibrous material in numerous vacuoles; and 3) progressive coalescence of osmiophilic bodies and degeneration of cytoplasmic contents. At 21 days, the seeds were dehydrated, mature and hard, but the thin, lateral subpalisade walls were still intact and had not broken. The thin‐walled portions were predetermined weak sites that break, permit palisade separation, expose the area under the blister to available moisture and result in subsequent imbibition of water by the seed. The hydrophilic, fibrous material extruded from the ruptured subpalisade cells may attract water to the newly exposed surface and facilitate penetration of water into the nutritive and embryonic seed tissues.
SEED PRODUCTION AND DISPERSAL IN DALECHAMPIA (EUPHORBIACEAE): DIVERGENT PATTERNS AND ECOLOGICAL CONSEQUENCES
Authors: Armbruster W. Scott
Published: January 2018

Patterns of capsule development and methods of seed dispersal are described and compared for 16 neotropical species of Dalechampia. In 15 species all the capsules in a single inflorescence develop simultaneously. In one species, D. spathulata, the capsules develop sequentially. I suggest that the difference between D. spathulata and the other species is the result of the fact that D. spathulata occurs in a low‐light, rainforest environment, whereas the other species grow in high‐light environments. Sequential development of capsules appears to reduce the loss of seeds to seed predators in species that occur in light‐limited environments. The seeds of all 16 species of Dalechampia are dispersed by explosive dehiscence of the capsules. Within the genus there are several different adaptations that increase the average dispersal distance for the seed crop.
FACTORS INFLUENCING SEED WEIGHT IN IMPATIENS CAPENSIS (BALSAMINACEAE)
Authors: Waller Donald M.
Published: January 2018

I analyzed within‐ and between‐plant variation in seed weight from one greenhouse and four natural populations of Impatiens capensis Meerb. Most variation in seed size in natural populations occurred within populations and within plants. Weights of seeds from cleistogamous flowers on greenhouse plants increased with height on the plant and proximity to the main stem, a result that may be related to the local supply of photosynthate. Mean seed weight in the natural populations declined during seed set, then increased again. Seeds from chasmogamous flowers were significantly larger in one of the four populations. Maternal parents differed significantly in both mean seed weight and the relative size of the two types of seeds. Combined genetic and general environmental effects accounted for 26% of the total phenotypic variance, which provides an outside estimate of the heritability of this character.
POPULATION DYNAMICS OF THE AMERICAN GINSENG PANAX QUINQUEFOLIUM (ARALIACEAE)
Authors: Lewis Walter H. , Zenger Vincent E.
Published: January 2018

A 3‐yr study of an aged population of American ginseng revealed four morphological classes among plants 1‐18 yrs old. The youngest and smallest plants had a single prong of 3‐5 leaflets and the oldest had four prongs with up to 20 leaflets. Age was positively correlated with prong and leaflet number. Prong development was linear, but not annual, i.e., a two‐pronged plant formed from the single prong stage on an average only after 4.5 years, a third prong arose after 7.6 years, and the fourth prong after 13.5 years. All one‐pronged plants were juveniles and, depending on the year, 22‐44% of two‐pronged plants were also juveniles. After the formation of an inflorescence during the two‐pronged stage, flowering was annual thereafter. Flower number per inflorescence was correlated with morphological class and age. Most plants that developed flowers formed fruit (80‐89%), except during the summer of 1980 when only 47% of flowering plants successfully matured fruit in a season typified by low precipitation and humidity, and high temperature. Younger adults in particular were more susceptible to failure in producing propagules and to earlier annual abscission under these stressful conditions than older members of the population. In fact, 53% of all flowering plants failed to develop fruit in 1980 compared to only 14% and 21% the previous 2 yrs. Seed survival was low and variable, the long afterripening period undoubtedly contributing to this vulnerable stage in the life cycle. Once germinated and established, however, seedling survival and development to adulthood, as well as adult survivorship, were high (97%). Even though a long‐lived, woodland geophyte, year‐by‐year fluctuations in reproductive capacity, seed germination, and time of aerial stem abscission were marked. Annual growing‐season dormancy, previously reported as a general phenomenon for American ginseng, was not found.
CELL WALL CONFORMATION IN DRY SEEDS IN RELATION TO THE PRESERVATION OF STRUCTURAL INTEGRITY DURING DESICCATION
Authors: Webb Mary Alice , Arnott Howard J.
Published: January 2018

Internal tissues of mature air‐dry seeds, prepared anhydrously for observation with the scanning electron microscope, exhibit cell wall structure which is different from that observed in aqueously fixed (hydrated) seed tissues. In a wide range of dry seeds observed (six members of the Cucurbitaceae, two species of Yucca, Hibiscus esculentus, Phaseolus vulgaris, and Helianthus annuus) cell walls exhibit a unique collapsed structure. The manner of cell wall collapse is characteristic for a given species and ranges from a highly regular folding pattern in the Cucurbitaceae to random wrinkling of the walls in Hibiscus. Evidence suggests that the regular patterns of wall folding may result from a mechanism located in the cell wall. Wall collapse in dry seeds is explained as a means of coordinating wall and protoplasmic shrinkage during desiccation and is thought to be essential for preserving the structural integrity of the tissue by conserving intercellular communication and plasmalemma‐cell wall association. Implications of these observations may relate to retention of viability in seeds.
POLLINATION BIOLOGY AND CHEMOTAXONOMY OF THE ECHINOCEREUS VIRIDIFLORUS COMPLEX (CACTACEAE)
Authors: Leuck Edwin E. , Miller John M.
Published: January 2018

The Echinocereus viridiflorus complex is morphologically distinct from other members of the genus. Temporal differences in flowering preclude natural interspecific hybridization between taxa of the E. viridiflorus complex and sympatric congeners. All taxa within the complex are xenogamous and self‐incompatible. Considerable taxonomic disagreement exists among herbarium and field botanists with regard to species boundaries and infraspecific classification of the taxa constituting the E. viridiflorus complex. One author views the complex as consisting of a single species, E. viridiflorus while other authors additionally recognize E. chloranthus, E. russanthus, and E. davisii. Pollination in E. viridiflorus is by solitary halictid bees. Photographs taken with a filter transmitting long‐wave ultraviolet (UV) light revealed two floral patterns among entities of the complex: entirely UV‐absorbing tepals and tepals with UV‐reflective outer segments and UV‐absorbing centers (target‐type blossoms). We suggest that UV‐floral patterning increases pollinator visitation and efficiency. Six flavonol‐O‐glycosides and two dihydroflavonol‐7‐O‐glycosides were localized in tepal tissue. No qualitative differences were seen either between differentially UV‐patterned flowers or among E. viridiflorus, E. chloranthus, E. davisii, and E. russanthus. Flavonoid evidence indicates that these taxa are conspecific.
THE DISTRIBUTION OF ANTHOCHLOR FLORAL PIGMENTS IN NORTH AMERICAN COREOPSIS (COMPOSITAE): TAXONOMIC AND PHYLETIC INTERPRETATIONS
Authors: Crawford Daniel J. , Smith Edwin B.
Published: January 2018

Anthochlors (chalcones and aurones) occur in floral tissues of all members of North American Coreopsis. The genus in North America consists of 46 species distributed in 11 sections, and a total of five chalcone aglycones are found in it. The chalcone butein occurs in all sections, and is the only anthochlor constituent in the closely related woody Mexican sections Electra and Anathysana. These two sections are viewed as primitive. The morphologically distinct but putatively unspecialized woody Mexican section Pseudo‐Agarista sequesters both okanin and butein; the same two anthochlors also characterize two additional sections of herbaceous perennials, Silphidium and Tuckermannia. Sections Euleptosyne and Pugiopappus, comprised of annuals restricted primarily to California, exhibit the rare chalcone stillopsidin in addition to butein and okanin. The remaining four sections, Palmatae, Coreopsis, Calliopsis and Eublepharis are among the more specialized in North America, and are sometimes considered to represent a distinct phyletic line or two related lines. All or some of the members of these sections sequester the very rare chalcone lanceolatin in floral tissues in addition to okanin.

Butein is also present in some or all species in each section, and isoliquiritigenin occurs rarely in two sections. Those sections considered more specialized have additional anthochlors relative to primitive sections, and any compound found in a more primitive section also occurs in a more advanced one. Thus, the trend in floral anthochlors in North American Coreopsis is toward increased number of compounds rather than reduction.
SALT REGULATION AND LEAF SENESCENCE IN AGING LEAVES OF JAUMEA CARNOSA (LESS.) GRAY (ASTERACEAE), A SALT MARSH SPECIES EXPOSED TO NaCl STRESS
Authors: Omer L. St. , Horvath S. M. , Setaro F.
Published: January 2018

The effects of increasing salt stress on leaf senescence and salt regulation were investigated in the halophyte Jaumea carnosa in hydroponic culture experiments. The plants were grown in Hoagland's nutrient solution plus additional NaCl salt (0, 300, 400, 500 mm NaCl). Decreases in nucleic acids, protein, and chlorophyll were used as indicators of leaf senescence. The results indicated no definitive pattern of acceleration in leaf senescence with increasing salt stress. Salt regulation was also unaffected as leaves aged under increasing NaCl concentrations. The results are consistent with those of previous studies of the halophyte which indicated that the species was very tolerant of high NaCl concentrations.
PHOTOGRAPHIC VISUALIZATION OF FLORAL COLORS AS PERCEIVED BY HONEYBEE POLLINATORS
Authors: McCrea Kenneth D. , Levy Morris
Published: January 2018

An inexpensive photographic technique for visualizing the ultraviolet and visible wavelengths perceived by honeybees is described. Using a standard daylight‐balanced color slide film and illumination from blacklight and filtered daylight fluorescent lamps, a recording balance was achieved which approximates the spectral sensitivity of the honeybee eye.

The technique was used to illustrate floral features among Rudbeckia species and among color morphs of Phlox. The Rudbeckia have inflorescences that are similar in visible coloration but distinctive in ultraviolet patterning and Phlox color morphs are distinctive in visible coloration but similar in ultraviolet patterning. The efficacy of the technique was judged from comparison with in vivo reflectance spectra of the floral subjects. Generally, photographic visualizations of entomophilous flowering plants portray only the ultraviolet or the visible components of floral coloration. This technique emphasizes the importance of considering the entire spectrum of floral colors relevant to most insect pollinators.
MORPHOLOGICAL AND ULTRASTRUCTURAL DEVELOPMENT AND STARCH ACCUMULATION DURING CHILLING OF SOUR CHERRY FLOWER BUDS
Authors: Felker Frederick C. , Robitaille Henry A. , Hess F. Dana
Published: January 2018

Floral tissue of dormant sour cherry (Prunus cerasus L.) flower buds was examined by light and electron microscopy during field development and laboratory chilling. Differentiation of flower parts ceased by early November and there was no further morphological development until visible signs of budbreak occurred after the end of rest. Pollen meiosis occurred at the half green budbreak stage. No ultrastructural changes accompanied chilling accumulation except development of numerous starch grains in plastids. Buds on cut shoots held at the non‐chilling temperature of 15 C developed more mitochondria but acquired no starch when compared with buds on cut shoots held at a 5 C chilling temperature. Nuclei and nucleoli enlarged with chilling in ovules and sporogenous cells but not in ovary parenchyma. Accumulation of starch with chilling in most bud tissues was demonstrated histochemically.
STUDIES OF PALEOZOIC FUNGI. I. THE STRUCTURE AND ORGANIZATION OF TRAQUAIRIA (ASCOMYCOTA)
Authors: Stubblefield Sara P. , Taylor Thomas N.
Published: January 2018

Traquairia is one of the several unusual fungal structures occurring in Pennsylvanian coal balls. Specimens were initially described from European sediments and are now known from the Pennsylvanian of North America. Although Traquairia was originally believed to be a protozoan closely related to the radiolarians, its structure and organization suggest affinities with members of the fungal group, Ascomycota. Specimens are irregularly shaped and up to 1.0 mm in diameter. Each cleistothecium bears prominent radiating spines that are continuous with a peripheral mat of extensively branched, delicate hyphal filaments. A complex wall encloses a central cavity which may contain a number of asci with ascospores. Among extant fungi, Traquairia is most similar in form to members of the Eurotiales and Erysiphales.
CAREX GRACEII SP. N., CYPEROCARPUS ELIASII SP. N., CYPEROCARPUS TERRESTRIS SP. N., AND CYPEROCARPUS PULCHERRIMA SP. N. (CYPERACEAE) FROM THE MIOCENE OF NEBRASKA
Authors: Thomasson Joseph R.
Published: January 2018

Silicified achenes and some perigynia of four new sedges are described from the late middle or late Miocene Ash Hollow (Clarendonian or Hemphillian) and early middle Miocene Sheep Creek (Late Hemingfordian) Formations of Nebraska. Carex graceii, sp. n., Cyperocarpus terrestris, sp. n., and Cyperocarpus pulcherrima, sp. n., were collected from strata in Garden and Antelope Counties and Cyperocarpus eliasii, sp. n., was collected from strata in Sioux County. Certain of the newly discovered taxa exhibit considerable anatomical detail of the pericarp wall of the achene. In two taxa, Carex graceii and Cyperocarpus pulcherrima, the achene pericarp exhibits four topographic regions: a cuticle, an outer layer of pentagonally to hexagonally shaped epidermal cells containing silica bodies, a middle layer of sclerenchyma cells, and an inner layer of sclerenchyma cells whose long axes are perpendicular to the long axes of the cells of the middle layer. Similar pericarp anatomy was found in Cyperocarpus terrestris except that the inner layer was not observed. In the fourth taxon, Cyperocarpus eliasii, only an outer epidermal layer of elongate cells with small protuberances is preserved. The ultrastructure of the pericarp of the fossil taxa is similar to that of living forms. Associated flora and fauna indicate widespread savanna environments with significant riparian elements. This is the first systematic treatment of sedges from the Miocene of North America.
HALF PSEUDOCOLPI, A UNIQUE FEATURE OF OLINIA (OLINIACEAE) POLLEN
Authors: Patel Varsha , Skvarla John J. , Raven Peter H.
Published: January 2018

We examined pollen of all five species of Olinia, the only genus of Oliniaceae (Myrtales), an endemic African family. Olinia pollen is heteropolar with one pole colpate and the other heterocolpate. Restriction of pseudocolpi to one polar face, hence, half pseudocolpi, the inequality of the two polar faces, and the unequal distribution of the colpus segments across the modal plane, are features that distinguish Olinia from all other Myrtales.