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from article Circadian clock (plants)
Three-module circadian clock system.
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Image
from article Circadian clock (plants)
Model of the Arabidopsis circadian clock, showing light input (bold arrow), the central oscillator (large box), and output/response (tinted arrows). Light signals synchronize the clock via the cryptochromes (cry) and phytochromes (phy). These are…
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from article Gibberellins
ent-Gibberellane carbon skeleton showing the carbon numbering system and ring designations.
Image
from article Gibberellins
The GA-biosynthetic pathway in higher plants via 2-methylerythritol-4-phosphate (MEP). The biologically active end products of the pathway are GA1, GA3, and GA4. The general diterpene precursor trans-geranylgeranyldiphosphate (GGPP) is formed in…
Image
from article Gibberellins
Mechanisms for GA inactivation. C19-GAs and C20-GAs may be oxidized on C-2 by different classes of GA 2-oxidases (GA2ox). In rice, the enzyme ELONGATED UPPER INTERNODE (EUI) oxidizes the 16,17-double bond of non–13-hydroxylated GAs, such as GA4, to…
Image
from article Gibberellins
DELLA protein showing conserved domains, and a model for DELLA degradation via the SCF E3 ubiquitin ligase, which consists of a DELLA-specific F-box, Skp1, Cullin1 (CUL), and Rbx1 subunits. Binding of the GID1-GA complex to DELLAs promotes…
Image
from article Gibberellins
Model for GA-induced production of α-amylase in the aleurone of germinating cereal grains. GAs produced in the scutellum diffuse to the aleurone cells, where they stimulate transcription, processing, and secretion of α-amylase and other hydrolytic…
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from article Chlorophyceae
Chlorococcales. (a) Chlorococcum (Chlorococcaceae), vegetative cell; (b) cell with zoospores; (c) zoospores; (d) Hydrodictyon (Hydrodictyaceae), portion of coenobium; (e) portion enlarged; (f) Dictyosphaerium (Dictyosphaeriaceae), colony in…
Image
from article Chlorophyceae
Filamentous green algae with chlorophycean ultrastructure. (a) Microspora (Microsporales), showing H-shaped wall segments; (b) Sphaeroplea (Sphaeropleales); (c) Chaetophora (Chaetophorales), heterotrichous thallus (erect and prostrate systems).
Image
from article Chlorophyceae
Ulothrix (Ulotrichales).
Image
from article Chicxulub impact crater
Bouguer gravity anomaly map over the Chicxulub impact crater. The coastline is designated by a thin white line, cenotes (natural pits) and sinkholes are designated by black dots, and the city of Mérida and the town of Chicxulub Puerto are designated…
Image
from article Chicxulub impact crater
Seismic line imaging of what lies beneath the seafloor, showing the Chicxulub impact crater. The crater includes many faults that can be grouped into an exterior ring fault, a series of outer ring faults, and a series of inner ring faults. Within…
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from article Osage orange
Fruit and foliage of osage orange (Maclura pomifera). (Photo copyright © Karren Wcisel)
Image
from article Bryopsidales
Anatomical structures of selected members of Bryopsidales. (a) Dichotomosiphon, filament with oogonia and antheridia. (b) Ostreobium, filaments. (c) Caulerpa, section of filament showing trabeculae. (d) Codium, group of utricles with gametangia and…
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from article Bryopsidales
Representative members of Bryopsidales. (a) Bryopsis; (b) Caulerpa; (c) Penicillus; (d) Halimeda; (e) Codium.
Image
from article Graptolithina
Sketches of portions of pterobranch and graptolite colonies showing the dwelling tubes and the constructional units of the graptolite skeleton. (a) Young Rhabdopleura compacta colony with founder zooid and first asexual bud (Recent). Benthic…
Image
from article Graptolithina
Scanning electron micrograph of a graptolite (Pseudoclimacograptus scharengergi) showing the fuselli (horizontal ridges) that compose graptolite thecae, and the cortical bandages (oblique strips) that were deposited on top of the fuselli (Middle…
Image
from article Graptolithina
Hypothetical form of zooids that inhabited colony tubes, based on a planktic graptolite. Large zooids are shown with possible oarlike swimming organs used to move the colony through the ocean water and tentacles for feeding. Also shown are two…
Image
from article Graptolithina
Examples of some planktic graptolites, reconstructed to show three-dimensional form.
Image
from article Ursa Minor
Modern boundaries of the constellation Ursa Minor, the Little Bear. The celestial equator is 0° of declination, which corresponds to celestial latitude. Right ascension corresponds to celestial longitude, with each hour of right ascension…
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from article Venus
Venus compared to Earth in size. Note that the image of Venus at left does not include the planet's thick, opaque atmosphere. The image was obtained by the Magellan spacecraft that orbited Venus from 1990 to 1994. Magellan used cloud-penetrating…
Image
from article Venus
Venus viewed in visible light by the Galileo spacecraft during a 1990 gravity assist flyby on the probe's ultimate journey to Jupiter. (Credit: NASA)
Image
from article Venus
Global Venus clouds, as viewed in the ultraviolet from Venus Express. These features can be used to track winds and atmospheric motion at the cloud tops. Convection clouds can be seen near the equator (top of image), whereas streaky brighter clouds…
Image
from article Venus
Inhomogeneities in the total thickness of the clouds between 48 and 70 km (30 and 43 mi) show up in the near-infrared. These clouds, seen only at night, are backlit from the hot atmosphere below it (similar to a Chinese lantern), where bright…
Image
from article Venus
Perspective view of the southern boundary of Laksmi Planum, a plateau 2.5–4.0 km (1.5–2.5 mi) high. (Credit: NASA/JPL)
Image
from article Venus
Magellan image of the central and northern parts of the highland region Ovda Regio (north at top). Ridges running approximately east-west (horizontally) have been interpreted as resulting from crustal shortening (compression). Ridges are cut by…
Image
from article Venus
Perspective view of a portion of the Western Eistla Regio, with a rift valley in the foreground and the volcanoes Gula Mons (right) and Sif Mons (left) on the horizon. (Credit: NASA/JPL)
Image
from article Venus
Sapas Mons, one of several large volcanic edifices that compose the broad equatorial rise known as Alta Regio. (Credit: NASA/JPL)
Image
from article Venus
Computer-simulated perspective view, based on data from Magellan spacecraft, showing three impact craters in the northwestern portion of Lavinia Planitia with diameters ranging from 37 to 63 km (23 to 39 mi). (Credit: NASA/JPL)
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from article Plant vulnerability to climate change
Subarctic tundra and vegetation of the Denali National Park and Preserve in Alaska. As a result of climate change and the resultant poleward and upward shift of plant ranges, plants and their ecosystems may become particularly vulnerable. (Credit:…
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from article Plant vulnerability to climate change
Blue grama (Bouteloua gracilis) growing in Montana. As a result of warming temperatures, this type of grass could face decreased productivity, allowing forbs to increase and making the ecosystem less tolerant of drought and grazing. (Credit: Matt…
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from article Plant vulnerability to climate change
Modeled distribution of suitable climate space in Europe for stiff sedge (Carex bigelowii), which is an Arctic-Alpine plant: (a) during the period 1961–1990 (green color = suitable climate space during the 1961–1990 period); (b) climate model…
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from article Plant vulnerability to climate change
The endangered western prairie fringed orchid (Platanthera praeclara) is declining across much of its range in North America. (Credit: U.S. Fish and Wildlife Service)
Image
from article Plant juvenility
The basic miRNA, siRNA, and ta-siRNA pathways in plants. The enzymes that carry out the different steps are written to the right of the downward arrows. The miRNA pathway schematic shows processing of the hairpin into an miRNA:miRNA* duplex by the…
Image
from article Plant juvenility
The developmental expression patterns of genes that regulate vegetative phase change. This graph is meant to show only the changes in expression for each gene during development rather than actual expression levels or relative levels between genes.
Image
from article Rosemary
Leaves of rosemary (Rosmarinus officinalis). (Photograph courtesy of Forest and Kim Starr)
Image
from article Palaeonisciformes
Mimia toombsi (Gardiner & Bartram, 1977), Late Devonian, Gogo, Australia. One of the earliest palaeonisciforms, reaching 15 cm (6 in.) long, and known by complete fossils. (Reprinted with permission from B. G. Gardiner, The relationships of the…
Image
from article Palaeonisciformes
Chirodus granulosus (Young, 1866) was a deep-bodied palaeonisciform that grew to 10 cm (4 in.) and lived in Carboniferous coal swamps of Britain. The teeth formed cutting blades that may have been used to crop vegetation. This reconstruction is…
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from article Squash
Zucchini (Cucurbita pepo), a type of summer squash, with flowers. (Credit: Howard F. Schwartz, Colorado State University/www.Bugwood.org)
Image
from article Squash
Crookneck squash (Cucurbita moschata). (Credit: Howard F. Schwartz, Colorado State University/www.Bugwood.org)
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from article Squash
Delicata squash (Cucurbita pepo), a variety of winter squash. (Credit: Shaun Case)
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from article Squash
Leaves of Cucurbita pepo infected by a squash mosaic virus. (Credit: William M. Brown, Jr./www.Bugwood.org)
Image
from article Astronomy
A photograph of the Milky Way in the night sky over the ESO 3.6-metre telescope, at right, at the La Silla Observatory in northern Chile. [Credit: ESO/B. Tafreshi ( twanight.org )]
Image
from article Astronomy
An artist’s impression of the exoplanet GJ 504, a world several times the size of Jupiter and anticipated to have a magenta color, still glowing from its initial formation. (Credit: NASA's Goddard Space Flight Center/S. Wiessinger)
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from article Astronomy
The Hubble Space Telescope in orbit above Earth. (Credit: NASA)
Image
from article Orbital motion
Orbital motion in a plane, in the shape of an ellipse, with the primary body at the focus F.
Image
from article Orbital motion
Orbit oriented in space with respect to a fundamental plane, in this case the celestial equator.
Image
from article Dormancy
Viviparous seeds of maize (Zea mays) germinating on the cob because of a mutation (vp14) preventing abscisic acid synthesis. (From S. H. Schwartz and J. A. D. Zeevaart, Abscisic acid biosynthesis and metabolism, pp. 137–155, in P. J. Davies, ed.,…
Image
from article Phaeophyceae
Embryonic sporophyte of Desmarestia anceps, showing trichothallic growth resulting in an embryonic stipe and several pairs of embryonic branches.
Image
from article Cladoselache
Cladoselache fyleri, from the Upper Devonian of Cleveland. (After S. E. Bendix-Algreen, 1975)
Image
from article Paleocopa
Paleocopa. (a) Ogmoopsis nodulifera, left valve; from the Ordovician of Sweden. (b) Eurychilina subradiata, right valve showing wide complete frill; Ordovician of Minnesota. (c) Sulcicuneus porrectinatium, male and female carapaces; Devonian of…
Image
from article Coriander
Coriander seeds (Coriandrum sativum). (Photograph courtesy of Steve Hurst, USDA–NRCS PLANTS Database)
Image
from article Strawberry
June-bearing strawberries (Fragaria × ananassa), which are produced in early summer. (Photo courtesy of Kimberly Lewers, Agricultural Research Service, United States Department of Agriculture)
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from article Strawberry
Botrytis cinerea fungal sporulation on a ripe strawberry. (Photo courtesy of Scott Bauer, Agricultural Research Service, United States Department of Agriculture)
Image
from article Scrophulariales
Flowers of the common snapdragon (Antirrhinum majus), a typical member of the family Scrophulariaceae in the order Scrophulariales (Lamiales). (Photo by Ondřej Zicha, BioLib, Czech Republic)
Image
from article Venus' flytrap
Dionaea muscipula (the Venus' flytrap) growing in a South Carolina nature preserve. Winged petioles and traps in various stages of the capture cycle are visible. The plant is surrounded by Sphagnum moss, which is a frequent community associate.…
Image
from article Venus' flytrap
Stages in the capture and digestion of a fly by the Venus' flytrap. A prey item is attracted to the trap margins by nectar (a). When a trigger hair on the inside leaf surface is twice stimulated (b), the trap closes rapidly (c). Complete closure is…
Image
from article Oats
Oats (genus Avena). (Photo by Jan Samanek, State Phytosanitary Administration, Czech Republic)
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from article Oats
Oat panicles with many branches and spikelets. (Photo by Jan Samanek, State Phytosanitary Administration, Czech Republic)
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from article Oats
Oat florets. Scale bar = 1 cm (0.4 in.). (Photo by Steve Hurst, USDA–Natural Resources Conservation Service PLANTS Database)
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from article Oats
Crown rust on oat leaves. This devastating disease is caused by Puccinia coronata. (Photo courtesy of the USDA Agricultural Research Service)
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from article Oats
Stem rust infection (caused by Puccinia graminis) on oat stems. (Photo by Howard F. Schwartz, Colorado State University)
Image
from article Mass–luminosity relation
Mass-luminosity relation, where the abscissa is the logarithm of mass M and the ordinate is the logarithm of luminosity L, both relative to the Sun as unit. This relation is typically plotted with the brightest, most massive stars at the upper left,…
Image
from article Cell plastids
Light microscope view of part of Hypochaeris radicata leaf, showing chloroplasts sectioned in a variety of planes and displaying internal grana.
Image
from article Cell plastids
Three-dimensional model of grana with intergranal connections. (After W. Wehrmeyer, Planta, 63:13–30, 1964)
Image
from article Cell plastids
Electron microscope view of two oat leaf chloroplasts, one showing successive layers of grana in side view, and the other showing grana in face view (disk shape of constituent thylakoid lobes are seen).
Image
from article Cell plastids
Part of oat leaf chloroplast at higher magnification. Grana are seen in side view, revealing profiles of membranes. Thylakoids that interconnect grana are shown, with components of stroma, or ground substance, in which thylakoids lie. The dense…
Image
from article Cell plastids
Proplastid in cell of broad bean root tip. Double membranous envelope is shown and rudimentary nature of internal membrane system is obvious.
Image
from article Milky Way Galaxy
The Milky Way as seen from the Atacama Desert in Chile at an altitude of around 3,650 m (12,000 ft), with large cacti silhouetted in the foreground. (Credit: ESO/S. Guisard )
Image
from article Milky Way Galaxy
An artist’s impression of the Milky Way Galaxy as seen from above and with the approximate location of the Sun labeled. [Credit: NASA/JPL-Caltech/R. Hurt (SSC)]
Image
from article Milky Way Galaxy
Infrared image of the Milky Way as seen from the location of the Sun, made from the 2MASS infrared sky survey. The image shows both the bulge and the disk of the Milky Way. Absorption by dust is minimized in the infrared, which accounts for the…
Image
from article Milky Way Galaxy
NGC 4603, a galaxy with a gross morphology similar to the Milky Way, seen obliquely. The spiral arms and the bulge are visible in the center. The bulge appears to be elongated because the galaxy also contains a bar, an extended feature containing…
Image
from article Milky Way Galaxy
A combination of X-ray and radio emission data from the core of the Milky Way, revealing the three-armed “minispiral” structure, with Sagittarius A* labeled, as well as other features including a jet blasted out by the supermassive black hole.…
Image
from article Virgo Cluster
Distribution of members of the Virgo Cluster on the sky, as determined in the du Pont Telescope survey. (After O.-G. Richter and B. Binggeli, eds., The Virgo Cluster, European Southern Observatory, 1985)
Image
from article Virgo Cluster
Central area of the Virgo Cluster, showing some of its brightest galaxy members. (Canada-France-Hawaii Telescope image courtesy of C. Cuillandre)
Image
from article Virgo Cluster
X-ray image of the entire Virgo Cluster. The main blob is centered on the giant active galaxy M87 (see Fig. 4). (Image from Roentgen Satellite (ROSAT) courtesy of NASA)
Image
from article Virgo Cluster
Giant elliptical galaxy M87. It is one of the brightest galaxies in the Virgo Cluster and is notable for its extremely massive central black hole. (Canada-France-Hawaii Telescope image courtesy of C. Cuillandre)
Image
from article Virgo Cluster
Sombrero Galaxy in an image obtained with the Spitzer Space Telescope. The spheroidal galaxy of stars hosts a thin, spiral-shaped ring of dust, visible in the infrared because of the light emission from the warm dust grains. (NASA/Spitzer Science…
Image
from article Pluto
An enhanced-color global view of Pluto taken by the New Horizons spacecraft on July 14, 2015, showing Pluto's diversity in surface texture and composition. The image (which actually is a mosaic of four images) resolves details on scales as small as…
Image
from article Pluto
Pluto and its five known moons, imaged by the Hubble Space Telescope on July 7, 2012. (Credit: NASA/ESA/Mark R. Showalter, SETI Institute)
Image
from article Pluto
A perspective view of the orbit of Pluto showing the inclination i and eccentricity of the orbit. The orbits of Jupiter, Saturn, Uranus, and Neptune are also shown. Terms: A, aphelion; P, perihelion; NN′, line of nodes. (Credit: Based on an original…
Image
from article Pluto
Two views of Pluto's vast nitrogen ice plain known as Sputnik Planitia. (Left) An enhanced-color close-up section of the glacial plains in the middle of Sputnik Planitia. (Right) A "scattering map" of the same region, created by combining two images…
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from article Pluto
Charon, pictured by New Horizons. (Credit: NASA/JHUAPL/SwRI)
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from article Herbig-Haro objects
Jet and bow-shock emission from Herbig-Haro 34. Two opposite jets run into the surrounding interstellar medium, where they terminate in Herbig-Haro objects with a characteristic bow-shock structure. The jets are composed of “bullets” of dense gas…
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from article Herbig-Haro objects
Spitzer Space Telescope infrared image and an optical Digital Sky Survey image of Herbig-Haro objects 46 and 47. The inset at the bottom left shows the optical image of the cloud in which the protostar is born and the associated Herbig-Haro objects…
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from article Herbig-Haro objects
Disk and jets associated with Herbig-Haro 30, showing changes between images taken in (a) 1995, (b) 1998, and (c) 2000 with the Wide Field and Planetary Camera 2 aboard the Hubble Space Telescope. A slightly flared disk of dust and gas appears…
Image
from article Patellogastropoda
Whitecap limpet (Acmaea mitra). (Photo by Douglas Eernisse)
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from article Patellogastropoda
Ribbed Mediterranean limpet (Patella ferruginea). (Photo by Georgina Rivera Ingraham)
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from article Patellogastropoda
Radula of the patellogastropod Notoacmea scapha.
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from article Fruit, tree
Apple trees growing in an orchard. (Photo by Charles Rondeau)
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from article Fruit, tree
Apple scab on fruit. This disease, caused by the fungus Venturia inaequalis, leads to unsightly blemishes on ripe apples. (Photo courtesy of the University of Georgia Plant Pathology Archive)
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from article Fruit, tree
Brown rot, caused by the fungus Monilinia fructicola, on a peach. (Photo by Jonas Janner Hamann, Universidade Federal de Santa Maria, Brazil)
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from article Fruit, tree
Fire blight, caused by the bacterium Erwinia amylovora, on apple fruits and leaves. (Photo courtesy of the University of Georgia Plant Pathology Archive)
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from article Fruit, tree
Blue mold (Penicillium italicum) on a rotting orange. (Photo by G. L. Barron)
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from article Funariales
Funariales sporophytes. (a) Funaria hygrometrica, entire plant (after H. S. Conard, How To Know the Mosses, Jaques, 1944); (b) deoperculate capsule; (c) capsule tip enlarged. (d) Physcomitrium turbinatum (P. pyriform), entire plant; (e) capsule…
Image
from article Acanthodii
Jaws of an Early Devonian ischnacanthid from northern Canada. The upper palatoquadrate and lower meckelian cartilages have tooth-bearing jawbones along their facing edges. (From University of Alberta, Laboratory for Vertebrate Paleontology…
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from article Acanthodii
Examples of acanthodians from the Early Devonian of northern Canada. (a) Primitive climatiiform Lupopsyrus. (b) Diplacanthid Tetanopsyrus. (c) Ischnacanthiform Ischnacanthus. (d) Unnamed mesacanthid acanthodiform. (From the University of Alberta,…
Image
from article Lichens
The ascolichen Teloschistes chrysophthalmus. (Credit: Jason Hollinger)
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from article Lichens
Cuplike lichens of the genus Cladonia. (Credit: Jacinta Lluch Valero)
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from article Ebony
Persimmon (Diospyros virginiana). (Photograph by Dot Paul, National Resources Conservation Service, USDA)
