Showing papers in "Botanical Gazette in 1983"
TL;DR: The effects of continuous, atmospheric CO2 enrichment on leaf anatomy and morphology were examined for corn, soybean, loblolly pine, and sweet gum, and there were no clear patterns in variation of stomatal frequency among treatments.
Abstract: The effects of continuous, atmospheric CO2 enrichment on leaf anatomy and morphology were examined for corn, soybean, loblolly pine, and sweet gum. Plants were exposed to constantly monitored CO2 levels of 340, 520, 718, and 910 ppm throughout the growing season in the field. Samples obtained from fully expanded leaves were subjected to routine anatomical procedures, sectioned transversely at 10 μm, and measured for total thickness and thicknesses of epidermal, palisade, and spongy mesophyll layers. Epidermal peels and scanning electron microscopy were used to observe possible changes in leaf surfaces Significant increases were measured in leaf thickness for the three C3 species under enriched CO2 conditions, but not for corn, a C4 plant. The influence of CO2 treatments on changes in stomatal indices was not significant, and there were no clear patterns in variation of stomatal frequency among treatments. Chloroplasts in leaf tissues of plants from CO2-enriched treatments appeared denser and were more dee...
219 citations
TL;DR: In spring, seeds are dormant; in summer, temperatures are too high for germination, and in winter, they are too low; Consequently, A thaliana behaves as a winter annual.
Abstract: Buried seeds of Arabidopsis thaliana exposed to natural seasonal temperature changes exhibited an annual dormancy/nondormancy cycle. The majority of freshly matured seeds were dormant. During burial in summer, fresh seeds and those that had been buried for 1 and 2 yr afterripened. During afterripening, seeds first germinated at 15/6 C and then at progressively higher temperatures until they were nondormant by October, when they germinated to high percentages at all thermoperiods except 35/20 C. Light was required for germination of both conditionally dormant and nondormant seeds. During autumn and winter, seeds reentered dormancy, first losing the ability to germinate at high and then at low temperatures. Thus, seeds can germinate in the field only in autumn, and germination is restricted to those seeds on or near the soil surface where both light and moisture can be nonlimiting In spring, seeds are dormant; in summer, temperatures are too high for germination, and in winter, they are too low. Consequentl...
115 citations
TL;DR: By coupling an absolute light requirement for germination with long-lived seeds, successional species of the upper Rio Negro region are able to persist in the soil seed bank until conditions favor their successful establishment.
Abstract: Two adjacent forest sites-a mixed forest on well-drained Oxisols and a caatinga forest on waterlogged Spodosols-were similar in the number of viable seeds m-2 in the seed bank: 180 for the mixedforest site, 200 for the caatinga site. Most germinated seeds were of successional pioneer tree species Seeds were entering the mixed-forest seed bank at a rate of ca 50 seeds m-2 yr-1. Agricultural and pasture sites tended to have larger seed banks (580-1,250 viable seeds m-2) composed almost entirely of grasses and forbs. The most common grass, forb, shrub, and pioneer tree species in the forest and disturbed-site seed banks (eight species in all) were tested for their ability to persist for 1 yr in open storage cans on the forest floor and for their response to a variety of germination triggers. Seeds of all species tested were still alive after 1 yr of incubation on the forest floor. In a lighted environment these species showed good germination under both moist and flooded conditions, but neither daily tempera...
108 citations
TL;DR: Temperate North American sphingophilous plant species fall into two classes in terms of their floristic affinities: subtropical or tropical species that extend north into the southern part of the United States, and new indigenous species that have evolved in temperate North America.
Abstract: A list of the plant species with hawkmoth flowers that occur naturally in temperate North America north of Mexico contains 105 species in 16 families; hawkmoth pollination records are available for 38 species in 12 families. The most important single plant group contributing hawkmoth flowers in temperate North America is Oenothera (40 species that collectively range throughout the entire area), followed by Nyctaginaceae (13 species in the Southwest), Amaryllidaceae (15 species in the South and Southeast), and Datura (five widely distributed species). Other plant groups are represented by only one or a few sphingophilous species. Temperate North American sphingophilous plant species fall into two classes in terms of their floristic affinities: (1) subtropical or tropical species that extend north into the southern part of the United States, and (2) new indigenous species that have evolved in temperate North America. The floral tube in most of these sphingophilous species is moderately long, 2-7 cm, corresponding to the proboscis length of common and widespread sphingids such as Hyles lineata. A number of sphingophilous species in the southern part of the United States have floral tubes of 9 cm or more. The southwestern sphingophilous species with very long tubes are associated with Manduca moths with correspondingly long proboscides. A comparable association may occur in the south-central and southeastern United States.
103 citations
TL;DR: Several hundred permineralized fragments of a single type of plant occur in upper Pennsylvanian coal balls from the Appalachian Basin, and these provide evidence for the description and complete reconstruction of a new heterosporous lycophyte.
Abstract: Several hundred permineralized fragments of a single type of plant occur in upper Pennsylvanian coal balls from the Appalachian Basin, and these provide evidence for the description and complete reconstruction of a new heterosporous lycophyte. Chaloneria cormosa gen. et sp. nov. is unbranched, ca. 2 m tall, and has a rounded rooting base. Secondary xylem is abundant at the base, diminishes distally, and is absent from the apical region. The stem has ligulate microphylls that are vegetative at proximal levels and grade upward into a fertile apex. Leaf cushions are not produced. In the fertile zone there are alternating regions of megasporophylls and microsporophylls. A second species, Chaloneria periodica sp. nov., has alternating vegetative and fertile zones and is based on Middle Pennsylvanian specimens that were previously referred to Polysporia mirabilis. Spores of both species are assignable to Valvisisporites and Endosporites. Plants with these sporomorphs comprise several genera rather than the sing...
88 citations
TL;DR: Variation in flower color, labellum morphology, and fragrance are described for four Panamanian species of Cycnoches previously considered to be C egertonianum Batem to indicate that each should be recognized as a well-defined species.
Abstract: Variation in flower color, labellum morphology, and fragrance are described for four Panamanian species of Cycnoches previously considered to be C egertonianum Batem A lack of odor detectable by nose or gas chromatography (GC) from C. aureum Lindl and distinct odor profiles obtained for C dianae Rchb. f, C densiflorum Rolfe, and C stenodactylon Schltr indicate that each should be recognized as a well-defined species. Odor profiles were calculated from fragrances produced by labella within 8 h of excision from the plants These profiles did not differ appreciably from those obtained from excised whole inflorescences or from flowers maintained on the plants Labella reliably produced copious amounts of fragrance compounds that were easy to concentrate within 1 h in small containers. Male and female flowers of each species produced the same scent Differences in odor profiles among individual plants occurred within sample populations Two fragrance chemotypes were detected by GC for C. densiflorum and C dianae I...
64 citations
TL;DR: Datura meteloides is pollinated mainly by long-tongued hawkmoths: Manduca quinquemaculata, M. sexta, and Hyles lineata and such alkaloids may well occur in the nectar also.
Abstract: Datura meteloides is pollinated mainly by long-tongued hawkmoths: Manduca quinquemaculata, M. sexta, and Hyles lineata. The most abundant and important of these species in the Arizona and New Mexico populations studied is M. quinquemaculata. There is good correspondence between the proboscis length of M. quinquemaculata (10 ± 1.2 cm) and corolla tube length of D. meteloides (10.5-11.0 cm) The Manduca moths feeding on D. meteloides flowers in the Arizona populations behaved in an intoxicated manner All parts of this plant, including the flowers, are known to contain tropane alkaloids, and such alkaloids may well occur in the nectar also. Intoxicating substances in nectar or other floral tissues could represent a new or little known type of floral reward to look for in other plant groups
64 citations
TL;DR: Two groups of Cycas may be recognized: the C. revoluta group with relatively small viable seeds that sink in water and float only when inviable, and the C circinalis-rumphii group with large seeds that float regardless of viability.
Abstract: A comparative morphological study of mature seeds of Cycas revoluta, C. media, C normanbyana, C. taiwaniana, and C. wadei revealed a three-layered seed coat consisting of sarcotesta, sclerotesta, and a thin membranous jacket Seeds of C circinalis, C rumphii, and C. thouarsii have an additional layer of spongy tissue, which causes flotation in water. It is speculated that long-distance dispersal of buoyant seeds occurs by the Indian Ocean currents, while nutritionally valuable starch in sarcotesta provides incentive for mammals to affect local dispersal across land Floating seed taxa differ only in minor morphological characters, despite their wide distribution, suggesting a single polymorphic species. Two groups of Cycas may be recognized: the C. revoluta group with relatively small viable seeds that sink in water and float only when inviable, and the C circinalis-rumphii group with large seeds that float regardless of viability.
62 citations
TL;DR: Notational conventions for spatial (Eulerian) and referential (Lagrangian) descriptions of growth in a root apex are discussed and a number of concepts that arise from these definitions, including the use of material derivatives and interconversion between spatial and refereNTial descriptions, are discussed.
Abstract: Notational conventions for spatial (Eulerian) and referential (Lagrangian) descriptions of growth in a root apex are discussed Root growth is assumed to be one-dimensional with generation of new length occurring as the result of cell division and cell expansion in the apical growth zone Growth in such a system may be described either in terms of activities at fixed distances from the apex or in terms of activities associated with elements of the root which move away from the tip during growth The first approach leads to a spatial description where growth variables, such as the spatial velocity field or cell density, are expressed as functions of position on the axis and of time The second approach gives a referential description of growth: here, growth variables are associated with marked particles of root material and are expressed as functions of the position that a particle occupies at a reference time, and of current time A number of concepts that arise from these definitions, including the use of mat...
59 citations
TL;DR: Stem anatomy is analyzed for 30 native species of nonsucculent desert and semidesert perennials from North America to reveal that the importance of sinking of stomates may not always have been in saving water, and some alternative hypotheses are suggested.
Abstract: Stem anatomy is analyzed for 30 native species of nonsucculent desert and semidesert perennials from North America. Observations on anatomical convergence of green-stemmed perennials from around the world are once again confirmed. Typical species have well-developed cuticle, sunken stomates, delayed formation of periderm, thick chlorenchyma, and much sclerenchyma in either the cortex or phloem or both. Four basic designs are recognized, based on the positions of supportive tissues versus chlorenchyma, and the origins of these types are discussed Each repetitious anatomical feature is analyzed by considering various physiological problems of living in deserts. Crude calculations on stomatal and superstomatal resistances of pores reveal that the importance of sinking of stomates may not always have been in saving water, and some alternative hypotheses are suggested.
58 citations
TL;DR: Rubber formation in stems of guayule, Parthenium argentatum Gray, first occurs in the cytoplasm of epithelial cells surrounding the resin ducts and eventually in the Cytoplasma of adjacent parenchyma cells.
Abstract: Rubber formation in stems of guayule, Parthenium argentatum Gray, first occurs in the cytoplasm of epithelial cells surrounding the resin ducts and eventually in the cytoplasm of adjacent parenchyma cells. With age, rubber droplets appear in the vacuoles of both cell types At maturity, rubber droplets increase in frequency and size, and most of the droplets occur in the vacuole. The rubber particles assume different shapes in each compartment-irregular or globoid in the cytoplasm, spherical in the vacuole. Guayule epithelial cells contain numerous plastids, mitochondria, microbodies, and Golgi bodies but do not contain lutoids The epithelial cells also are rich in smooth endoplasmic reticulum, which is often associated with complex tubular membrane structures that may be involved in the production and secretion of terpenoid substances found in the resin ducts
TL;DR: The development of idioblastic oil cells in the mesocarp of avocado fruit was studied with the electron microscope and formation of the complex cell wall and on the process of oil accumulation were concentrated on.
Abstract: The development of idioblastic oil cells in the mesocarp of avocado fruit was studied with the electron microscope. Observations concentrated on the formation of the complex cell wall and on the pr...
TL;DR: Grafting showed that the scion, not the rootstock, determined phenotype and there was no evidence for a diffusible, fasciation-determining substance transported up or down the stem, so Fasciation could not be mimicked or delayed by external application of growth regulators.
Abstract: Two sets of isogenic soybean lines were used to study fasciation inheritance and to compare growth morphology between fasciated and nonfasciated genotypes. The three sources of fasciated soybean mutants have the same allele for fasciation, inherited as a single-gene recessive. No linkages were found for fasciation (f) and flower color (w), pubescence color (t), seed-coat peroxidase level (ep), or an asynaptic mutant (st2). Furthermore, f was not linked to a chromosome interchange or located on any of the three soybean primary trisomics. Grafting showed that the scion, not the rootstock, determined phenotype. There was no evidence for a diffusible, fasciation-determining substance transported up or down the stem. Fasciation could not be mimicked or delayed by external application of growth regulators. Fasciated plants had wider and heavier main stems, but total shoot dry weights at maturity were similar for fasciated and nonfasciated genotypes. Stem circumference at the middle and upper portions of the sho...
TL;DR: The results support the conclusion that plants can effectively utilize NH4 + as a nitrogen source as long as root-zone pH is strictly controlled and a balance is maintained between carbohydrate availability and acquisition ofNH4 +.
Abstract: Plants supplied with moderate concentrations of NH4 + in solution generally grow poorly compared with plants supplied with other sources of nitrogen. Experiments were conducted with a flowing solution culture system to determine whether growth restrictions could be avoided over an extended period in the presence of NH4 + if root-zone pH were strictly controlled and if plants were exposed to NH4 + during exponential growth when carbohydrate fluxes to the root are coordinated with the rate of nitrogen acquisition. Vegetative soybeans (Glycine max [L.] Merrill) initially were exposed to complete nutrient solutions containing NO3 - until the exponential growth stage and then were exposed for 4 wk to solutions in which nitrogen was supplied as either 1.0 mM NH4 +, 1 0 mM NO3 -, or 0.5 mM NH4 + plus 0.5 mM NO3 -. Acidity of the solutions was constantly maintained at pH 5 8 ± 0 1 by automated control In separate experiments, irradiance (photosynthetic photon flux density [PPFD] of 700 and 325 μE m-2 s-1) levels ...
TL;DR: Megaspores and megagametophytes that exhibit a wide range of variability were discovered within sporangia of the Pennsylvanian fossil lycophyte, Chaloneria cormosa, and are grouped into the Chaloneriaceae fam.
Abstract: Megaspores and megagametophytes that exhibit a wide range of variability were discovered within sporangia of the Pennsylvanian fossil lycophyte, Chaloneria cormosa. The smallest megaspores occur in tetrahedral tetrads, with larger specimens preserved individually. Full-sized megaspores are often devoid of contents, but some show cellular megagametophytes entirely within the spore, or megagametophytes that protrude out of the trilete and display several archegonia. The range of variability is compared with developmental variations in extant and other fossil lycophytes to interpret megaspore and megagametophyte ontogeny and several aspects of reproductive biology in Chaloneria. Based on numerous similarities to Isoetes and to the Mesozoic Pleuromeia complex, Chaloneria and several other Paleozoic lycophytes are grouped into the Chaloneriaceae fam. nov and placed within the Isoetales.
TL;DR: The capacity of buds to break dormancy after summer rain thus appears to be adaptive in Mediterranean habitats.
Abstract: At Wagga Wagga, N.S W, Australia, 23 Mediterranean accessions of Phalaris aquatica L were grown in one or more of five field experiments One or more rainstorms in each summer interrupted the phase of dormancy conditional on drought, thus enabling estimates to be made of the comparative levels of regrowth capabilities of the accessions The accessions differed significantly in summer regrowth, and these values were inversely related to the proportion of plants surviving through one or more summers Summer regrowth levels were positively correlated with rainfall during the hottest 4 mo in the original habitats, except those with only 0-6 mm of summer rain; in the latter habitats, accessions may have high, medium, or low regrowth Summer regrowth was not related to summer temperature or daylength in the original habitats Little genetic variation for summer regrowth remains within populations compared with that between them. Broad-sense heritability within populations was 0.03 ± 0.08 in one experiment and 0.37 ±...
TL;DR: It is concluded that cytoplasmic modification of the endosperm cells in the micropylar region is necessary for the completion of germination in lettuce achenes, in addition to the necessity for decrease in embryo water potential.
Abstract: The endosperm structure of dark-germinating Grand Rapids lettuce (Lactuca sativa L.) achenes was examined by light microscopy under different germination conditions. Achenes imbibed in darkness at 25 C show significant structural modifications in a restricted area of the endosperm, opposite the radicle tip, before radicle emergence. These preemergence changes, similar to those observed in light-requiring Grand Rapids lettuce achenes after phytochrome activation, are mainly characterized by the mobilization of storage materials and the vacuolation of the cytoplasm Achenes imbibed under conditions not permitting the completion of germination (continuous far-red light, high temperature, and appropriate osmotic solution) do not show any structural change in their endosperm cells. We conclude that cytoplasmic modification of the endosperm cells in the micropylar region is necessary for the completion of germination in lettuce achenes, in addition to the necessity for decrease in embryo water potential.
TL;DR: It is suggested that mechanical injury causes a localized increase in the potential of the imbibed water and that the resulting increase inthe supply of water to the embryo triggers the onset of germination.
Abstract: In experiments conducted under controlled conditions, the water content of dormant caryopses of Avena fatua L. reached a maximum of ca. 75% (dry weight basis) after 5 days of imbibition of water. The rate of germination induced by piercing the seed coat of the imbibed caryopsis was inversely related to the distance of the hole from the embryo Germination was not prevented by covering the hole with lanolin and was significantly accelerated when the hole was covered with wet filter paper Experiments in which the caryopsis was cut transversely gave similar results. We suggest that mechanical injury causes a localized increase in the potential of the imbibed water and that the resulting increase in the supply of water to the embryo triggers the onset of germination.
TL;DR: The gynoecium was the most variable flower part and varied independently of the other parts, which tended to vary in a coordinated fashion, compared with other examples of abnormal merism in the Polemoniaceae.
Abstract: The numbers of flower parts are considered among the most constant angiosperm characters However, nearly 33% of the plants in 13 populations of Ipomopsis aggregata in Colorado had at least one anomalous flower, and almost 10% of the flowers displayed abnormal merism (abnormal floral formulas) Floral inconstancy varied significantly among populations The number of abnormal flowers per plant increased with the proportion of plants displaying abnormal merism at a given site Abnormal flowers were nonrandomly distributed; more plants had multiple anomalous flowers than expected by chance The gynoecium was the most variable flower part and varied independently of the other parts, which tended to vary in a coordinated fashion These observations are compared with other examples of abnormal merism in the Polemoniaceae
TL;DR: Testa development was compared in normal and hull-less strains of Cucurbita pepo L and Expression of the mutant phenotype was particularly evident in the seed margin where hypodermal tissue normally contributes substantially to overall testa thickness.
Abstract: Testa development was compared in normal and hull-less strains of Cucurbita pepo L. Histochemical studies showed that both normal and hull-less mutant seeds develop a five-zoned testa between 5 and 10 days post-anthesis Because of limited secondary wall development in the epidermis, hypodermis, and sclerenchyma in testae of the hull-less mutant cultivars, individual tissue layers began to compress between 20 days post-anthesis until the seed reached maturity. In the hull-less mutant, complete desiccation of seeds removed from the fruit resulted in complete collapse of the hypodermis, sclerenchyma, and parenchyma. These tissues remain largely intact in normal seeds. Expression of the mutant phenotype was particularly evident in the seed margin where hypodermal tissue normally contributes substantially to overall testa thickness. Analyses of testa composition revealed a marked reduction in lignin (83%), cellulose/hemicelluloses (67%), and protein (54%), and increases in ethanol-soluble material (58%) and li...
TL;DR: The uniformity in wood anatomy between these fossils and the extant genera of the Engelhardieae suggests that a common pattern of anatomy, established during or prior to the Eocene, has been retained despite the morphological differentiation of fruits and foliage.
Abstract: Fossil wood representing the tribe Engelhardieae of the Juglandaceae is reported for the first time. The genus Engelhardioxylon is created to accommodate fossil woods with anatomy like that of modern genera in the Engelhardieae. Two middle Eocene species of Engelhardioxylon are described, one from eastern Oregon (E. nutbedensis) and one from southeastern Texas (E. texana). The anatomy of these fossils is indistinguishable from that of the modern genera of the Engelhardieae, i.e., Engelhardia, Oreomunnea, and Alfaroa. The uniformity in wood anatomy between these fossils and the extant genera of the Engelhardieae suggests that a common pattern of anatomy, established during or prior to the Eocene, has been retained despite the morphological differentiation of fruits and foliage.
TL;DR: The development and ultrastructure of glandular trichomes of Glycine max (soybean) leaves have been characterized from initiation through maturation and senescence on mature leaves.
Abstract: The development and ultrastructure of glandular trichomes of Glycine max (soybean) leaves have been characterized from initiation through maturation and senescence on mature leaves. They develop from a single epidermal cell and at maturity contain five cells in a linear arrangement, including a basal cell that is continuous with the epidermal layer The nuclei of the upper four cells are centrally placed At initiation of secretion the cuticle separates from the primary cell wall at a region between the uppermost two cells The gland cells are enriched in dictyosomes, rough endoplasmic reticulum, and small vesicles. Plasmodesmata occur in high frequency between gland cells but are fewer between the basal cell and adjacent leaflet cells. The plastids of the upper two cells are unique in that they are closely associated with the nuclei and contain membrane aggregations surrounded by osmiophilic globules, membrane-bound crystalline structures, and starch granules but no grana or thylakoids During gland senescen...
TL;DR: The results suggest that SO2 adversely affects sexual reproduction in G carolinianum by the inhibition of pollen germination on the stigmatic surface, which causes a subsequent reduction of seed set.
Abstract: Exposure of Geranium carolinianum L flowers to 0.6 ppm SO2 at 90% relative humidity (RH) for 8 h during anthesis reduced the number of germinated pollen grains per stigma, the percentage of pollen germination, and the number of seeds per flower (seed set). Similar exposures at 70% and 80% RH had no effect Regardless of RH, exposure to SO2 had no effect on the total number of pollen grains transferred to the stigma (self-pollination) or on pollen-tube growth in the style. A 6-h exposure to 0.6 ppm SO2 at 90% RH begun immediately after hand pollination reduced seed set by 20%, but a similar exposure begun 30 min after pollination had no effect on seed set. The results suggest that SO2 adversely affects sexual reproduction in G carolinianum by the inhibition of pollen germination on the stigmatic surface, which causes a subsequent reduction of seed set
TL;DR: It is suggested that CAM and succulence are often associated in drought-adapted plants because both characters have been selected for in arid environments.
Abstract: Crassulacean acid metabolism (CAM) and succulence were compared in two species of Peperomia (Piperaceae) and six species of Cissus and Cyphostemma (Vitaceae) The species include thin-leaved plants, leaf succulents, and stem succulents Succulence at the organ or the cellular level (mesophyll succulence [Sm]) does not appear to be causally related to CAM Peperomia, with high Sm, shows low CAM activity, while Cyphostemma, with relatively low Sm, exhibits very high CAM activity Overnight accumulation of malic acid as high as 332 μeq/g fresh weight was measured in the nonsucculent, thin leaves of Cissus sp, while only 50 μeq of malic acid per gram fresh weight accumulated in the succulent, photosynthesizing stem of the same plant In the thin-leaved species of Cissus, CAM does not appear to be related to drought adaptation Succulence in the CAM species Cissus may be a new acquisition that has allowed the genus to spread from the wet tropics to arid environments We suggest that CAM and succulence are often assoc...
TL;DR: The most striking phenomenon was the accumulation of large amounts of the colorlessCarotenoid precursor phytofluene, which amounted to 20% and 67% of the total carotenoids in the endocarp and flavedo, respectively.
Abstract: Pigment changes in the flavedo and endocarp of the developing pummelo, Citrus grandis `Goliath,' were investigated at four ripening stages: green, color break, almost ripe, and fully ripe. In the flavedo, chlorophyll of the green fruit decreased abruptly and was totally absent in the fully ripe, lemon-yellow fruit, which contained only carotenoids However, the total colored carotenoid content decreased from 26 μg/g in the green fruit to 5 μg/g in the fully ripe fruit. The pulp of the endocarp, characterized as "colorless," contained small amounts of chlorophyll and 0 4 μg/g total colored carotenoids which remained nearly at the same level in all ripening stages. The carotenoid pattern at the green stage of both the flavedo and the endocarp was that of the chloroplast type During ripening, the four chloroplast carotenoids decreased gradually, and typical chromoplast carotenoids-such as ζ-carotene, neurosporene, mutatochrome, cryptoxanthin, and its 5,8-epoxide-appeared The most striking phenomenon was the a...
TL;DR: There were no differences among the host species in the number of mistletoes occurring on infested trees and the occurrence of the mistletoe varied with geography, host species, and host size.
Abstract: The comparative distribution and abundance of Phoradendron villosum subsp villosum were described on three species of California oaks (Quercus agrifolia, Q douglasii, and Q lobata) at 21 field sites between San Francisco and Santa Barbara The occurrence of the mistletoe varied with geography, host species, and host size Quercus agrifolia, an evergreen black oak, was virtually uninfested at the sites north of Arroyo Grande but was infested south of Arroyo Grande In contrast, Q douglasii and Q lobata, both deciduous white oaks, were infested at northern and southern sites Infested trees tended to be larger than uninfested trees in the three host species There were no differences among the host species in the number of mistletoes occurring on infested trees
TL;DR: An ovulate pinaceous cone and associated needles, wood, and pollen cones were found permineralized within a small lens of chert in sediments of Middle Eocene age near Smithers, B.C. and may represent parts of the same plant.
Abstract: An ovulate pinaceous cone and associated needles, wood, and pollen cones were found permineralized within a small lens of chert in sediments of Middle Eocene age near Smithers, B.C. The ovulate cone, Pinus driftwoodensis sp.n., is cylindrical, about 3 cm long and 2.7 cm in diameter. Ovuliferous scales have swollen apices and an umbo lacking a spine. Pith and cortex of the axis are parenchymatous. The narrow vascular cylinder includes a ring of up to 70 resin canals. The trace to each bract and its associated ovuliferous scale arises as a single unit, circular in cross section, with an abaxial resin canal system. Two ovules with well-developed integuments but little internal tissue are borne on each ovuliferous scale. Pinaceous leaves, in two-needle fascicles, are associated with the cone. These needles contain two vascular bundles, numerous medial resin canals, stomata on both abaxial and adaxial surfaces, and a uniform hypodermis. Associated wood and small twigs have pinoid resin canals, heterogeneous ra...
TL;DR: Plants of a drug strain of Cannabis sativa L -grown 33 days under daylight, shaded daylight conditions, filtered green, blue, and red light, and darkness- were analyzed by gas-liquid chromatography for their cannabinoid content.
Abstract: Plants of a drug strain of Cannabis sativa L -grown 33 days under daylight, shaded daylight conditions, filtered green, blue, and red light, and darkness-were analyzed by gas-liquid chromatography for their cannabinoid content. The highest content of cannabinoids, predominantly Δ9-tetrahydrocannabinol (Δ9-THC) in this strain, occurred in the youngest leaves of daylight-grown plants Leaves at successively lower nodes of this control condition and all treated plants subsequently grown in daylight contained progressively lower levels of cannabinoids Leaves from plants grown under filtered green light and darkness contained significantly lower levels of Δ9-THC than those from plants grown in daylight However, the Δ9-THC content of leaves from plants grown under shaded daylight and filtered red and blue light did not differ significantly from the Δ9-THC content in daylight controls, indicating that these conditions did not alter the synthetic rate of this cannabinoid The cannabichromene (CBC) content of plants...
TL;DR: T. lanceolatum was clearly the most toxic species tested, its extracts and volatiles greatly suppressing growth of the indicators, but when the extracts were inoculated with 0.5 g soil and incubated several months at room temperature, most gradually diminished in toxicity.
Abstract: We tested 55 plant species in northern California for water-extractable and volatile inhibitors of plant growth with seed bioassays: 69% significantly inhibited, and none significantly stimulated, radicle growth of Hordeum vulgare when tested as 1:25 or 1:50 (g tissue:ml water) extracts, whereas 38% inhibited and 15% stimulated Bromus mollis. Extracts of species in the Compositae and Labiatae, as well as Aesculus californica, Ailanthus altissima, Brassica nigra, Ceanothus integerrimus, Lupinus arboreus, Nicotiana glauca, Ribes cereum, and Scrophularia californica, were the most inhibitory. Only Artemisia tridentata, Heteromeles arbutifolia, Salvia sonomensis, and Trichostema lanceolatum released strongly inhibitory volatiles; T. lanceolatum was clearly the most toxic species tested, its extracts and volatiles greatly suppressing growth of the indicators. Five of the species most inhibitory in the initial screening were selected for further investigation Their extracts reduced germination and growth of a n...
TL;DR: Investigation in two "normal" genotypes and two genotypes lacking L-1 activity in mature seeds found dry-matter accumulation patterns during seed development and germination were similar in all four genotypes, and changes in L-2 plus -3 activity per milligram extracted protein and total L- 1 activity per seed decreased as germination proceeded.
Abstract: Dry-matter accumulation, extracted protein, lipoxygenase-1 (L-1), and lipoxygenase-2 plus -3 (L-2 plus -3) were investigated in two "normal" genotypes and two genotypes lacking L-1 activity in mature seeds. Dry-matter accumulation patterns during seed development were similar in all four genotypes. Protein extracted during seed development or the first week of germination also showed similar profiles for the four genotypes. Changes in L-2 plus -3 activity per milligram extracted protein and total L-2 plus -3 activity per seed again showed similar profiles for all four genotypes during seed development and germination. L-2 plus -3 activity was maximal between days 5 and 20 before physiological maturity and again maximal between days 4 and 7 of germination. The two soybean genotypes that did not have L-1 activity in mature seeds also lacked detectable L-1 activity throughout seed development and the first week of germination. The two normal soybean genotypes displayed similar profiles of L-1 activity. L-1 a...