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Botanika (88)

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! EN_90246533_0001 SCI
PHOTO: EAST NEWS/SCIENCE PHOTO LIBRARY St John's wort. Illustration of the flowers and leaves of a St John's wort plant (Hypericum perforatum), which is used in herbal medicine. St John's wort grows wild throughout Europe in dry and sunny positions. The leaf tips and flowers are used to treat a variety of ailments, but are most commonly used as an anti-depressant. Tablets made up of concentrated parts of the plant can be bought for this purpose. In traditional herbal medicine, the preparations were used for treating intestinal parasites, lung disorders, bladder problems and diarrhoea. In ancient times, the plant was used to ward off evil spirits.
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! EN_90246679_0003 SCI
PHOTO: EAST NEWS/SCIENCE PHOTO LIBRARY Cannabis. Computer artwork of the leaf of the hemp or marijuana plant, Cannabis sativa. This plant is used as an intoxicating drug. Native to central Asia it is cultivated for three products: fibre from the stems, seed oil, and the drug. The active ingredient of the drug is a resin from glandular hairs on the leaves, stems and flowers. The plant is a fast-growing annual and a common weed in northern India. In good conditions it can grow to over five metres tall. Male and female flowers are borne on different plants, the females being the most potent as the drug is most concentrated in them.
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! EN_90246571_0001 SCI
PHOTO: EAST NEWS/SCIENCE PHOTO LIBRARY Mineral deficiencies in leaves. Illustration of the leaves of a plant, showing the effect of excessive use of fertiliser versus various mineral deficiencies. The growing seedling (at centre right) should have sufficient room in its pot to grow and absorb fertiliser nutrients. At top, a surplus of fertiliser will cause green leaves to curl under. At centre left, nitrogen deficient leaves become pale in colour. Phosphorus deficiency is manifested in curled leaves with purplish undersides (lower left). While a leaf suffering a lack of potassium develops bronze edges (at bottom right).
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! EN_90246639_0001 SCI
PHOTO: EAST NEWS/SCIENCE PHOTO LIBRARY Shepherd's Purse. Illustration of the Shepherd's Purse plant, Capsella bursa-pastoris. The plant is seen with flowering parts (at right) and without. The pubescent basal leaves form a rosette with a tap-root; erect stems bear white-petalled flowers at their tips; the fruits are triangular (as seen beneath the flowers) containing oval seeds. The whole plant can be used for medicinal properties, including the treatment of uterine haemorrhage, nose bleeds, urinary calculosis, and was at one time a drug for malaria. Shepherd's Purse grows profusely as a garden weed and on waste ground, widespread throughout Europe.
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! EN_90246540_0001 SCI
PHOTO: EAST NEWS/SCIENCE PHOTO LIBRARY Dicotyledon leaf. Illustration showing the anatomy and cell structure of a dicotyledon leaf. The lower surface of the leaf is seen at top. Stomata (brown, pores) are present on the lower epidermis through which gaseous exchange occurs. Under the one- cell thick epidermis, two layers of mesophyll cells are found. Spongy mesophyll (green) consists of loosely packed cells; a palisade layer (yellow) contains cells important in photosynthesis. At centre left, a leaf vein (vascular bundle) is surrounded by a bundle sheath (orange); within the sheath are xylem (pink) and phloem (white) cells which transport water and nutrients.
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! EN_90263828_0001 SCI
PHOTO: EAST NEWS/SCIENCE PHOTO LIBRARY Flower anatomy. Illustration of parts of a flower, seen in longitudinal section. The flower is borne on a stalk, with the floral parts attached to a thickened receptacle. Sepals (green) are leaf-like structures that enclose and protect the flower when it is still a bud. Larger petals (red) are usually brightly coloured and may serve to attract pollinators. Within the petals are the male stamens, each made up of a filament and an anther bearing pollen. At centre is the female ovary (here cut through) bearing one or more ovules which may become seeds. The ovary has a long style with a stigma at its tip.
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! EN_90246566_0001 SCI
PHOTO: EAST NEWS/SCIENCE PHOTO LIBRARY Illustration of the vascular system in a plant root. Cross-sections through different layers of this root show elements of its internal anatomy. At lower frame, surface root hairs are involved in water absorption from the soil; the single outer layer of cells (exodermis) and thicker cortex are seen. At centre, the root's internal vascular system contains different types of cells: four groups of phloem cells (two groups are visible here, dark brown); a central area of angular xylem cells with thick lignified walls. Xylem vessels transport water and mineral salts from the root upwards; phloem conducts food down to the root.
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! EN_90254260_0001 SCI
PHOTO: EAST NEWS/SCIENCE PHOTO LIBRARY Cutaway illustration of a plant chloroplast, the unit within the leaf which manufactures the plant's food supply - starch - during photosynthesis. Contained within a double unit membrane are sheet- like lamellae (also called thylakoids) that support the the granal stacks, represented here as stacks of coins. The grana contain the photosynthetic pigments (chlorophylls) which are active in the conversion of the sun's energy into chemical energy. The chloroplast's internal structure is adapted to maximise the amount of light reaching the chlorophyll pigments.
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