{"id":40027,"date":"2019-07-16T21:15:02","date_gmt":"2019-07-16T21:15:02","guid":{"rendered":"http:\/\/www.labri.fr\/perso\/barla\/blog\/?p=40027"},"modified":"2020-04-12T21:44:52","modified_gmt":"2020-04-12T21:44:52","slug":"natures-palette","status":"publish","type":"post","link":"https:\/\/www.labri.fr\/perso\/barla\/blog\/?p=40027","title":{"rendered":"Nature&#8217;s palette"},"content":{"rendered":"<p id=\"top\" \/>\n<p><em>by David Lee<\/em><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Nature&#8217;s Palette<\/h3>\n\n\n\n<p><strong>Absorbance of light by plant pigments is due to the repetition of basic structural units that move the peak of absorbance toward the visible<\/strong>, modified by chemical structures attached to the basic molecule that may further affect absorbance in the visible wavelengths. &#8211; p.62<\/p>\n\n\n\n<p>All higher plants produce two chlorophyll molecules; chlorophyll <em>b<\/em> is derived from <em>a<\/em> by a single chemical step. These two molecules, the most abundant pigment molecules on earth; have slightly different absorbance spectra. Both absorb in the blue and red wavelengths, but in chlorophyll <em>b<\/em> the blue peak absorbs at a longer wavelength and the red peak absorbs at a shorter wavelength than chlorophyll <em>a<\/em>. &#8211; p.64<\/p>\n\n\n\n<p>The <strong>yellow and orange<\/strong> colors of many flowers are caused by the accumulation of <strong>carotenoid pigments in the chromoplasts<\/strong> of petal cells. The wavelengths of absorbance of these pigments are influenced by their length and the numbers of double carbon bonds, so they can produce a fairly broad range of colors. &#8211; p.69<\/p>\n\n\n\n<p>The <strong>flavones<\/strong> produce <strong>ivory or cream colors<\/strong>, and the <strong>flavonols <\/strong>produce <strong>yellows<\/strong>. The <strong>anthocyanins<\/strong>, exceedingly important in plants, produce <strong>orange-red to violet colors<\/strong>. &#8211; p.73<\/p>\n\n\n\n<p>The number of anthocyanins (pigment attached to sugar) is very large, because of the types of sugars and their positions of attachment. All of them share the basic strong absorbance peak at the middle of our visual spectrum, with minor (but important) differences among different types. &#8211; p.75<\/p>\n\n\n\n<p>Plants can <strong>combine these separate pigments<\/strong> to absorb more evenly across the visible spectrum, producing <strong>browns grading toward blacks<\/strong>, depending upon their balance and concentration. Plants also produce molecules that give brown to black colors; most are <strong>complex molecules derived from the fusion of simpler molecules. The rapid production of brown<\/strong> (and eventually black) in plants is seen in many injured tissues; a cut apple turns brown. &#8211; p.79<\/p>\n\n\n\n<p><strong>Tannins are mostly brown colors<\/strong>, but what about black? In many animals including humans, <strong>brown and black pigmentation<\/strong> are produced by complex aromatic molecules, <strong>melanins<\/strong>. &#8211; p.80<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">The canvas<\/h3>\n\n\n\n<p><strong>Plants are much more like a watercolor than an oil or acrylic painting<\/strong>. The plant organs, particularly leaves and flower petals, are structurally complex features that efficiently absorb or reflect different wavelengths of light, depending on the requirements of the plant. <strong>Thus leaves and flowers are optical organs.<\/strong> &#8211; p.82<\/p>\n\n\n\n<p>The slight differences in refractive indexes of the different cell components provide conditions of<strong> weak reflectance at boundaries between<\/strong> them, as between <strong>the cytoplasm and a chloroplast, or even between structures within the chloroplasts<\/strong>. However, these differences are small compared with that between the refractive index of air (1.0) and the cell wall (around 1.40). The greater density of cell contents, and the higher refractive indexes of cell components, means that <strong>light is strongly reflected from this surface when it contacts air. Even within the cell<\/strong>, differences in refractive indexes cause some scattering of light. &#8211; p.84<\/p>\n\n\n\n<p>In the <strong>satin leaf tree<\/strong> (fig. 4.1), the <strong>undersurface hairs are colored light brown by deposits of tannins<\/strong>. The resulting reflectance is a <strong>bronze color<\/strong>, and the flat and parallel arrangement of the hairs gives the leaves their <strong>satin appearance<\/strong>. &#8211; p.85-86<\/p>\n\n\n\n<p><strong>Cells whose outer wall rises into a pointed tip<\/strong> may be particularly effective in absorbing light in a diffuse environment. Such shape reduces the likelihood of surface reflection at oblique angles. <strong>Side illumination is more likely absorbed by the steeply pitched walls, and direct illumination glances off the surface more directly into an adjacent cell<\/strong>. <strong>A more rounded external wall can function like a miniature lens<\/strong>, refracting light into a place in the interior of the organ-into a spot of higher intensity. Such lens-like cells would be less effective in capturing diffuse radiation than the cone-shaped external cells above. &#8211; p.86-87<\/p>\n\n\n\n<p>These differences in light absorption, between chlorophyll in solution compared to a structure with pigments in plastids, and between a structure with air spaces and one cleared of air spaces, are due to two important optical properties of plant tissues: scattering or path-lengthening effects, and packaging or sieving effects. &#8211; p.93<\/p>\n\n\n\n<p>The effect of <strong>path-lengthening on absorption by pigments<\/strong> <strong>requires <\/strong>that the pigments be in the midst of the region of <strong>air spaces in the plant organ<\/strong>. <strong>If the air spaces are near the outside<\/strong>, then much of the radiation scatters directly back to the exterior without alteration by absorption. In such cases <strong>the reflected light looks silver<\/strong> despite the presence of pigments beneath the spaces. Such spaces also decrease the amount of light transmitted through the organ. &#8211; p.94<\/p>\n\n\n\n<p>In the art of watercolor, water-soluble pigments are brushed onto the paper and coat the cellulose paper fibers evenly. When sunlight illuminates the painting, the scattered light passes through the pigmented coatings and is reflected from the paper fibers to produce brilliant colors. In plant cells, however, pigments are not so evenly distributed. <strong>Pigments are always sequestered in a portion of the cells.<\/strong> &#8211; p.95<\/p>\n\n\n\n<p>The optical implications of packaging effects are important. <strong>When pigments are in small particles, it is more likely that light will pass through a structure<\/strong>, even when scattered, <strong>without encountering a pigment molecule<\/strong>. Path-lengthening effects may actually decrease the capture of photons at wavelengths most effectively absorbed by a particular pigment. Thus <strong>packaging (sometimes also called sieving) helps explain the reduced efficiency of chlorophyll absorbance by leaves in the blue and red<\/strong> portions of the spectrum. &#8211; p.95-96<\/p>\n\n\n\n<p>Another implication of the packaging of pigments into structures within cells is that their positions at different times may affect the amount of color that is produced. If the organelles are placed along the sides of the cells, in relation to the surface of the structure and the direction of illumination, the probability of their absorbing light is decreased, and the light is more effectively transmitted through the tissue. Such tissue would produce little color. However, if the organelles are placed along the outer and inner margins of the cell, more parallel to the surface of the organ, the likelihood of their capturing light is much greater. Such an arrangement would more effectively intercept light and could produce color both through transmission and reflection of the light. Thus<strong> the movement of organelles within cells is an effective mechanism for changing their optical properties.<\/strong> &#8211; p.96-97<\/p>\n\n\n\n<p><strong>Because of the complexities of plant organs, there are no completely satisfactory models of their leaf properties to date<\/strong>. It is not difficult to understand why: once light enters the leaf, it encounters internal cell structures and intercellular spaces at crazy angles. These surfaces cause the partial reflectance of light, lengthening its path through the leaf. Furthermore, the reflectance from these surfaces is best described as diffuse, and not specular adding to the complexity of the patterns. Such scattering of light, and the possibility of refraction&#8217;s locally focusing light within the plant organ, may produce higher light intensity at certain points within the structure than that on the surface. These patterns of light absorption may be particularly important for certain plant organs. &#8211; p.99<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Leaves<\/h3>\n\n\n\n<p>Plants adapted to intense light conditions, or leaves acclimated to these conditions, may produce less pigment and more enzymes, as the latter may limit the rate of photosynthesis. Plants adapted, or acclimated to, very shady conditions do the opposite, allocating more of their nitrogen to pigments and less to enzymes. The pigment concentrations affect light absorption, and color, but the distribution of pigments in organelles is equally important. &#8211; p.128<\/p>\n\n\n\n<p>Many plants deviate strongly from the normal greens of foliage because they produce various structures that scatter light directly at the surface of the leaf. These <strong>structures include hairs, scales, and waxy coatings<\/strong>. &#8211; p.131<\/p>\n\n\n\n<p>When hairs are produced exclusively on the leaf undersurface, they reduce water loss and increase the efficiency of light absorption by the leaves. <strong>Light<\/strong> that passes through the leaf, both through packaging and scattering effects, <strong>is backscattered into the leaf upon encountering the hairs on the undersurface.<\/strong> This increases the total absorption of the leaf, and foliage of such plants, as in satin leaf and in snakewood, is dark green. &#8211; p.131<\/p>\n\n\n\n<p><strong>Waxes can give leaves a glaucous or white color<\/strong>, the intensity depending on the amount of deposition. <strong>When particularly small particles are deposited<\/strong>, they are more effective at scattering shorter wavelengths of light, <strong>more blue than yellow or red<\/strong>. Some leaves, such as those of blue spruce, look powdery blue. &#8211; p.133<\/p>\n\n\n\n<p>Some <strong>variegation <\/strong>in tropical understory plants<strong> is at least partly due to the production of anthocyanins in areas of the leaf-blade<\/strong>. This may be joined by the absence of chlorophyll in other leaf areas, giving a variety of color patterns. Such a leaf may have dark brown areas (chlorophyll and anthocyanin), bright red areas (anthocyanin alone), white areas (no pigments), and normal green (chlorophyll alone). &#8211; p.143<\/p>\n\n\n\n<p>Since many plants may be strongly shade-adapted as small seedlings, and more sun-adapted as adults, they often produce variegated leaves as juveniles and normal green leaves as adults. Such patterns are observed in different developmental stages of vines. &#8211; p.145<\/p>\n\n\n\n<p>When leaves produce both chlorophyll and anthocyanin in proper balance the absorptions of the pigments combine to efficiently capture the visible wavelengths of light. The result is a brown, or almost black, color. Some leaves produce this color uniformly on the surface, or as variegation on a light background. Such color may actually camouflage a living leaf so that it appears dead to a potential herbivore. &#8211; p.146<\/p>\n\n\n\n<p><strong>One possible consequence of focusing is that a fleck of direct sunlight could be directed into the leaf at such high intensities as to destroy the chloroplasts. So such a feature must occur in very shady habitats.<\/strong> A possible benefit of such epidermal cells is that they are more efficient in capturing oblique rays of diffuse sunlight. which would normally reflect off the leaf surface. A cell shape optimal for absorbing the oblique rays would be more conical and less rounded. &#8211; p.149<\/p>\n\n\n\n<p>In many plants, including algae and mosses, chloroplasts can quickly change position, in a few minutes, after exposure to direct light. The chloroplasts typically move from the bottom of the palisade cells to the sides of the cells.<strong> This shift in position makes the cells more transparent to light, as more light can be transmitted through the cells without encountering any chlorophyll molecules.<\/strong> &#8211; p.150-151<\/p>\n\n\n\n<p>Leaves that develop beneath flowers become intensely colorful in a few plants. They thus compensate for the lack of visual attractiveness of the flowers, and may supply visual signals to attract agents of pollination. &#8211; p.153<\/p>\n\n\n\n<p>Leaves provide subtle signals of color that we can use to learn about the function of plants in their landscapes. The more knowledgeable we become about the identity of individual plants in their landscapes, the more sensitive we become to slight shifts in hue, intensity, and saturation. Each species responds to its physical environment in a distinct pattern, and each &#8220;behaves&#8221; in a particular way; in its rhythm of flowering, fruiting, and producing and shedding leaves. We call such rhythms of activity the phenology of a particular species. &#8211; p.155-156<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Flowers<\/h3>\n\n\n\n<p>Willsditter extracted cyanidin from the petals of red roses. The orange-red color of geranium (Pelargonium) yielded the anthocyanidin pelargonidin. Mallows (Malva sp.) yielded malvidin, and peonies (Paeonia sp.) yielded peonidin. These last two pigments produce colors rather similar to cyanidin. The colors of violet-blue flowers are due to the presence of delphinidin, extracted from Delphinium. These pigments absorb in the blue-green region of the visual spectrum, and transmit and reflect blue and red wavelengths. The small differences in the absorbance ranges of these pigments alter the amount of blues and reds reflected and dramatically change the hues. Thus the slight shift in the absorbance of delphinidin to longer wavelengths adds more blue wavelengths to the reds, producing the violet colors we are accustomed to in many flowers. &#8211; p.170-172<\/p>\n\n\n\n<p>The red-purple varieties of Bougainvillea, so important in tropical landscapes, are produced by quite different pigments, the betalains. &#8211; p.173<\/p>\n\n\n\n<p>Carotenoid pigments also vary in their cutoff of visible light absorbance, producing yellow through red colors as the cutoff wavelengths increase. &#8211; p.174<\/p>\n\n\n\n<p>Yellow flowers are produced by quite different pigments. In addition to the yellows produced by carotenoid pigments, quite common in sunflowers and other members of the aster family as well as in yellow tulips and pansies, yellows are also produced by individual flavonoid pigments, such as the flavonols and aurones. &#8211; p.175<\/p>\n\n\n\n<p><strong>Most flower colors are produced by mixtures of pigments.<\/strong> Thus hues can be altered by small changes in the proportions of pigments. A mixture of anthocyanins produces subtle colors in a variety of flowers, from pink to purple. Yellow to orange colors may be produced by mixtures of carotenoids, and by mixtures of flavonols and aurones, along with anthocyanins. &#8211; p.176<\/p>\n\n\n\n<p>Although the numbers of anthocyanins, flavonols, and carotenoids are not great, particularly compared to the range and subtlety of flower colors, they can be chemically modified to alter their color properties in new directions. &#8211; p.178<\/p>\n\n\n\n<p>The flavonoid pigments, most important in producing flower colors, are in solution in the vacuoles of cells. Their production of color is affected by interactions with other molecules in solution. Individual molecules, such as anthocyanins, may also associate with other flavonoid pigments, to increase stability, increase absorbance, and alter color properties. When another flavonoid, such as a flavonol, is mixed with an anthocyanin, the two molecules interact to form loose complexes that shift the wavelength of absorbance toward longer wavelengths (and produce colors toward blue). Anthocyanins are also affected by the acidity of the vacuole solution; they are unstable at more alkaline conditions. Even mild shifts in acidity may alter their absorbance and color properties. The charge in the middle ring of anthocyanins promotes association with ions in solution, such as the positively charged metal ions magnesium and aluminum. These ions may add to stability and alter color production. It should be clear by now that flower color, at least its chemical basis, can be very complicated. &#8211; p.179-180<\/p>\n\n\n\n<p>Several mechanisms, all involving the\nalteration of anthocyanin pigments, produce brilliant blues. &#8211; p.180<\/p>\n\n\n\n<p>Some flowers shift through a range of colors\nin the process of attracting pollinators and being fertilized. &#8211; p.183<\/p>\n\n\n\n<p>The petal surface and distribution of intercellular spaces in the interior strongly affect the intensity and efficiency of floral coloration. The distribution of pigments within flowers may also be important. Most flowers produce convexly curved surfaces that effectively capture light, and most produce pigments in the outermost layer (the epidermis), where they are most likely to receive light. &#8211; p.185<\/p>\n\n\n\n<p>Most flowers make their yellow-orange and red-purple pigments water-soluble by attaching one or more sugars to the molecules. These are then shunted into the large vacuoles of the pigmented cells, filling some 90 percent of the cell volume with pigments. This location increases the likelihood of their absorbing light, and makes for more efficient color production. However, pigments may be present as small particles. Flowers with yelIow-orange carotenoid pigments (such as the French marigold) produce them in small plastids in the periphery of the cells, around the vacuole. &#8211; p.187<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Fruits and seeds<\/h3>\n\n\n\n<p>The &#8216;Red Delicious&#8217; is a solid red, caused by the accumulation of a single anthocyanin, cyanidin-3-giucoside, in the epidermis and layers immediately beneath. The pigment appears to be sequestered in large bodies within the cell vacuoles.<strong> Light passing through these pigmented layers is scattered by the white fruit tissue beneath, and reflected back out of the surface. <\/strong>&#8211; p.202 <em>There seems to be a gradient of concentration.<\/em><\/p>\n\n\n\n<p><strong>The pale to yellow colors of fresh peaches are caused by mixtures of carotenoid pigments<\/strong>, principally beta-carotene. The reddish brown burnish on the shoulder, most exposed to the sun, is due to the addition of anthocyanin pigment, cyanidin-3-g1ucoside. &#8211; p.205<\/p>\n\n\n\n<p><strong>The brilliant red of strawberries is the simple consequence of the accumulation of many anthocyanins<\/strong>, but especially pelargonidin-3-glucoside, in the epidermis and layers beneath.\u00a0 &#8211; p.205<\/p>\n\n\n\n<p>Different varieties of bell pepper mature as\ngreen, yellow, orange, red, or purple fruits. The green fruits produce\nchloroplasts in their outer layers, giving the brilliant green color of these\nvarieties. In both the yellow and red varieties, carotenoid pigments,\nsequestered in chromoplasts, are responsible for the colors. In the red bell\npeppers, the pigments lycopene&nbsp; and\ncapsanthin are responsible for the brilliant red color. &#8211; p.206<\/p>\n\n\n\n<p>The principal red pigment, lycopene, gets its name from the original genus of tomato. The outer layer contains high concentrations of this pigment in chromoplasts, and the pigment decreases in concentration toward the center of the fruit. &#8211; p.207<\/p>\n\n\n\n<p>Although there are white and purple varieties of eggplants in our markets, most varieties are a dark purple-black. The pigment mostly responsible for this intense dark color is the anthocyanin delphinidin-3-rhamnoside, with a residue of coumaric acid added to the sugar to shift the absorbance toward purple. &#8211; p.208<\/p>\n\n\n\n<p>The colors of the orange and its numerous\nrelatives are primarily due to the production of carotenoid pigments in the\nrind. Carotenoids, particularly beta-carotene, are largely responsible for the\nyellow-orange of the rind and the pulp (and juice) of oranges and other fruits.\n&#8211; p.208<\/p>\n\n\n\n<p><strong>The colors of mango fruit vary from green to yellow-orange. and are caused by an accumulation of carotenoid pigments<\/strong>, especially beta-carotene in the outer wall of the fruit, and in the flesh as well. In some varieties, the shoulder or even the entire fruit may turn reddish from the production of anthocyanins. In others, the fruits stay green from the persistence of chloroplasts in the outer layers. &#8211; p.210<\/p>\n\n\n\n<p>Squash colors vary from green (chlorophyll in\nchloroplasts) to orange (carotenoids in chromoplasts). &#8211; p.210<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Stems and roots<\/h3>\n\n\n\n<p>Lignin does not color wood or bark significantly by itself; it is mainly a cement that makes the walls of the conductive vessels and fibers terrifically strong. <strong>Smaller complexes of molecules in wood give it color, the lignans.<\/strong> &#8211; p.240<\/p>\n\n\n\n<p><strong>Condensed tannins may accumulate in bark and produce reddish or darker colors; these may also be present in the heartwood. <\/strong>The color partly depends upon the shapes and distributions of cells in the phellum. Dark corky barks are produced by phellum heavily suberized throughout the tissue. Lighter-colored barks are suberized, but <strong>air spaces in the tissue or between separate layers allow for some backscattering of light<\/strong>. Phellum produced in thin papery layers impregnated with suberin may allow light to penetrate and be reflected out through the surface, producing more orange-red colors, like the thin layers in the gumbo-limbo. &#8211; p.240 <em>Interesting layered structure.<\/em><\/p>\n\n\n\n<p>Stems and other plant parts may produce color from fluids that are exuded when tissues are wounded. &#8211; p.240<\/p>\n\n\n\n<p>Members of the poison ivy family (Anacardiaceae) often produce long chain aromatic compounds with economic value. When exposed to air, these same compounds are oxidized and produce black stains. &#8211; p.243<\/p>\n\n\n\n<p>The attractiveness of the wood of many trees is due to the way that the secondary xylem, or conductive tissue, is formed, as well as the chemicals that are deposited in the old tissue, principally in the center part of the trunk: the heartwood. &#8211; p.244<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Iridescent plants<\/h3>\n\n\n\n<p>More familiar to most of us are the waxy varieties of many conifer trees, particularly the blue spruce. <strong>The needles of this tree are coated with small wax particles. These particles are so small that they scatter radiation more effectively at short wavelengths.<\/strong> Given the distribution of sunlight and our visual sensitivity, we observe this scatter as a blue color. This selective scattering is a physical phenomenon, called Tyndall scattering, and it is also responsible for the blue color of the sky and the ocean. &#8211; p.255<\/p>\n\n\n\n<p>Figure 10.6 &#8211; p.258<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Why leaves turn red<\/h3>\n\n\n\n<p>The leaves of witch hazel are typical of the species that turn yellow. As the aging chloroplasts lose chlorophyll, the carotenoid pigments become more visible. Eventually all chlorophyll break down, some carotenoid pigments remain, and the leaves are a brilliant yellow. The leaves of the red oak are fairly typical of the species that turn red. In red oak anthocyanins begin to accumulate in the vacuoles of the palisade mesophyll layer of the leaf when part of the original chlorophyll concentration is lost. The final color is thus a blend between the anthocyanins produced in vacuoles, some carotenoids in the old chloroplasts, and the removal of chlorophyll. <strong>The anthocyanins are clearly being produced while leaves are in decline, when about half of the chlorophyll has already broken down.<\/strong> &#8211; p.285-286<\/p>\n\n\n\n<p><strong>Both red and yellow leaves contain about the same amounts of carotenoid pigments, which decline in concentration as chlorophyll degrades and the leaves prepare to detach from the trees<\/strong>. &#8211; p.286-287<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Chlorophilia<\/h3>\n\n\n\n<p>The greatest shift in the distribution of wavelengths in the shade compared to sun is barely beyond the limits of human vision, in the far-red region of the spectrum. This is particularly well documented by the <strong>ratio of the red and far-red regions. In sunlight the ratio is around 1.2, while in forest shade it is around 0.3. Plants have evolved an elegant system of perception of the shifts in these two bands with the phytochrome pigment.<\/strong> This pigment detects the ratio of these two wavelengths as an equilibrium between the chemically distinct red (R) and far-red (FR) arms of the molecule. Since this ratio is strongly influenced by green foliage, either transmitted through it or reflected from the foliage surface, plants have thus evolved an elegant means of determining the presence of nearby plants. Many of the plant growth responses to the red:far-red ratio improve their ability to compete against other plants, as in growing taller by stretching more and allocating fewer resources to make roots. &#8211; p.303<\/p>\n\n\n\n<p>If we could perceive the subtle wavelength changes produced by vegetation, it would not be the color green, but would more likely be the color blue-which is reduced in the understory where there is a slight increase in green. So light effects might be in a wavelength range that is a consequence of the absorption of sunlight by foliage, and not green directly. &#8211; p.305<\/p>\n","protected":false},"excerpt":{"rendered":"<p>by David Lee Nature&#8217;s Palette Absorbance of light by plant pigments is due to the repetition of basic structural units that move the peak of absorbance toward the visible, modified by chemical structures attached to the basic molecule that may further affect absorbance in the visible wavelengths. &#8211; p.62 All higher plants produce two chlorophyll &#8230; <a title=\"Nature&#8217;s palette\" class=\"read-more\" href=\"https:\/\/www.labri.fr\/perso\/barla\/blog\/?p=40027\" aria-label=\"Read more about Nature&#8217;s palette\">Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[621],"tags":[],"class_list":["post-40027","post","type-post","status-publish","format-standard","hentry","category-books"],"_links":{"self":[{"href":"https:\/\/www.labri.fr\/perso\/barla\/blog\/index.php?rest_route=\/wp\/v2\/posts\/40027","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.labri.fr\/perso\/barla\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.labri.fr\/perso\/barla\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.labri.fr\/perso\/barla\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.labri.fr\/perso\/barla\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=40027"}],"version-history":[{"count":14,"href":"https:\/\/www.labri.fr\/perso\/barla\/blog\/index.php?rest_route=\/wp\/v2\/posts\/40027\/revisions"}],"predecessor-version":[{"id":40330,"href":"https:\/\/www.labri.fr\/perso\/barla\/blog\/index.php?rest_route=\/wp\/v2\/posts\/40027\/revisions\/40330"}],"wp:attachment":[{"href":"https:\/\/www.labri.fr\/perso\/barla\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=40027"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.labri.fr\/perso\/barla\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=40027"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.labri.fr\/perso\/barla\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=40027"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}