Autumnal coloring

Canney, F. C., Cannon, H. L.,Cathrall,J. B. Robinson, K. (1979)- Autumn colors, insects, plant disease, and prospecting. Economic Geology, 74, 1673-76. 

What do the following have in common An athlete is disqualified from the Olympics for illegal use of anabolic steroids. You spray a bread pan with canola oil to keep the bread from sticking. Your mother is rushed to surgery to remove a gallbladder packed with cholesterol. You wax your shiny new car with carnauba wax. Your father is treated with a prostaglandin to lower his blood pressure. An artist uses turpentine to thin her brushes after painting the brilliant autumn colors. 

Weigelas are opposite-leaved, deciduous shrubs grown for their bright flowers, which appear in late spring and early summer. Because they lack interesting fruit and autumn color, weigelas are best used in the mixed shrub border. 

Polyenes, CH2(=CH-CH) =CH2, have been discussed in previous chapters. The transitions to the first and second excited state are either strongly allowed ( A or forbidden ( A 2 Ap and go into the visible region for long chains (red, brown, and yellow autumn colors). If the number of carbou atoms teuds to infinity, there appears to be a remaining gap of 1.5-2 eV, contrary to the case of graphene, where the gap has closed. This is directly connected to Peierls distortion to alternating bond lengths in the one-dimensional case. Peierls distortion cannot take place in the two-dimensional case. 

The bright colors of flowers and the varied hues of autumn leaves have always been a cause for delight, but it was nor until the twentieth century that chemists understood how these colors arise from the presence of organic compounds with common structural features. They discovered how small differences in the structures of the molecules of these compounds can enhance photosynthesis, produce important vitamins, and attract pollinating bees. They now know how the shapes of molecules and the orbitals occupied by their electrons explain the properties of these compounds and even the processes taking place in our eyes that allow us to see them. 

During autumn (fall), mushrooms with egg-shaped, grey-white fruiting bodies occasionally appear, very often on road-sides, which after a few days deliquesce into an ink-colored liquid. The mushroom, Coprinus atramentarius, or inky cap, is edible when young, but can cause alcohol incompatability when consumed before, or together with, ethanol. 

Tennant investigated it carefully m an attempt to alloy lead with it, and concluded that it contained a new metal (17). In the autumn of the same year H.-V. Collet-Descotils, a friend and pupil of N.-L. Vauquelin, found that this powder contains a metal which gives a red color to the precipitate from an ammoniacal platinum solution (18). When Vauquelin treated the powder with alkali he obtained a volatile oxide which he believed to be that of the same metal with which Descotils was dealing (19). 

As flavonoids and flavanones contribute to the yellow color in both white and red wines, anthocyanins 42 and their mono- and diglucosides are the bright red pigments in grapes, mainly in the skin, but in autumn also in the leaves. These components contribute only slightly to the taste but as... 

Other pigments, called antenna pigments, or accessory pigments, absorb light at other wavelengths. The accessory pigments are responsible for the brilliant colors of plants in the autumn (in the Northern Hemisphere). The breakdown of chlorophyll allows us to see the colors of the accessory pigments. 

Maples are characterized by the shape of their leaves, which in most species are broadly palmate with a three- or five-lobed outline, and are arranged in an opposite fashion on their branches. Maples have seasonally deciduous foliage, which is shed in the autumn. The leaves of many species of maples develop beautiful yellow, orange, or red colors in the autumn, prior to shedding for the winter. Maple flowers appear early in the springtime, and consist of non-showy, rather inconspicuous inflorescences. The flowers of some species produce nectar and are insect-pollinated, while other species shed their pollen into the air and are wind-pollinated. Maples have distinctive, winged seeds known as samaras, which are arrar ed in opposite pairs. 

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