Phloem: Plant tissue that carries nutrients, especially sucrose, by turgor pressure. Movement is bidirectional, in contrast to XYLEM where it is only upward. Phloem originates and grows outwards from meristematic cells (MERISTEM) in the vascular cambium. P-proteins, a type of LECTINS, are characteristically found in phloem.Cucurbita: A plant genus of the family CUCURBITACEAE, order Violales, subclass Dilleniidae, which includes pumpkin, gourd and squash.Plant Exudates: Substances released by PLANTS such as PLANT GUMS and PLANT RESINS.Xylem: Plant tissue that carries water up the root and stem. Xylem cell walls derive most of their strength from LIGNIN. The vessels are similar to PHLOEM sieve tubes but lack companion cells and do not have perforated sides and pores.Plant Structures: The parts of plants, including SEEDS.Plant Stems: Parts of plants that usually grow vertically upwards towards the light and support the leaves, buds, and reproductive structures. (From Concise Dictionary of Biology, 1990)Cucurbitaceae: The gourd plant family of the order Violales, subclass Dilleniidae, class Magnoliopsida. It is sometimes placed in its own order, Cucurbitales. 'Melon' generally refers to CUCUMIS; CITRULLUS; or MOMORDICA.Plant Leaves: Expanded structures, usually green, of vascular plants, characteristically consisting of a bladelike expansion attached to a stem, and functioning as the principal organ of photosynthesis and transpiration. (American Heritage Dictionary, 2d ed)Apium graveolens: A plant species of the family APIACEAE. The stalks are a food source.Plasmodesmata: Membrane-like channels of cytoplasm connecting adjacent plant cells. Plasmodesmata connect through pores in the CELL WALL and associate with the CYTOSKELETON machinery. They are essential for intercellular transport and communication.Scrophulariaceae: The figwort plant family of the order Lamiales. The family is characterized by bisexual flowers with tubular corollas (fused petals) that are bilaterally symmetrical (two-lips) and have four stamens in most, two of which are usually shorter.Cucumis sativus: A creeping annual plant species of the CUCURBITACEAE family. It has a rough succulent, trailing stem and hairy leaves with three to five pointed lobes.Aphids: A family (Aphididae) of small insects, in the suborder Sternorrhyncha, that suck the juices of plants. Important genera include Schizaphis and Myzus. The latter is known to carry more than 100 virus diseases between plants.Sucrose: A nonreducing disaccharide composed of GLUCOSE and FRUCTOSE linked via their anomeric carbons. It is obtained commercially from SUGARCANE, sugar beet (BETA VULGARIS), and other plants and used extensively as a food and a sweetener.Plant Proteins: Proteins found in plants (flowers, herbs, shrubs, trees, etc.). The concept does not include proteins found in vegetables for which VEGETABLE PROTEINS is available.Carbohydrate Metabolism: Cellular processes in biosynthesis (anabolism) and degradation (catabolism) of CARBOHYDRATES.Ricinus: A plant genus of the family EUPHORBIACEAE, order Euphorbiales, subclass Rosidae. The seed of Ricinus communis L. is the CASTOR BEAN which is the source of CASTOR OIL; RICIN; and other lectins.Plantago: A plant genus of the family Plantaginaceae. The small plants usually have a dense tuft of basal leaves and long, leafless stalks bearing a terminal spike of small flowers. The seeds, known as PSYLLIUM, swell in water and are used as laxatives. The leaves have been used medicinally.Cambium: A layer of living cells between the bark and hardwood that each year produces additional wood and bark cells, forming concentric growth rings.Plants, Genetically Modified: PLANTS, or their progeny, whose GENOME has been altered by GENETIC ENGINEERING.Bignoniaceae: A plant family of the order Lamiales. The family is characterized by oppositely paired, usually compound leaves and bell- or funnel-shaped, bisexual flowers having a five-lobed calyx and corolla.Plant Roots: The usually underground portions of a plant that serve as support, store food, and through which water and mineral nutrients enter the plant. (From American Heritage Dictionary, 1982; Concise Dictionary of Biology, 1990)Plant Vascular Bundle: A strand of primary conductive plant tissue consisting essentially of XYLEM, PHLOEM, and CAMBIUM.Papaveraceae: The poppy plant family of the order Papaverales, subclass Magnoliidae, class Magnoliopsida. These have bisexual, regular, cup-shaped flowers with one superior pistil and many stamens; 2 or 3 conspicuous, separate sepals and a number of separate petals. The fruit is a capsule. Leaves are usually deeply cut or divided into leaflets.Gene Expression Regulation, Plant: Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control of gene action in plants.Vitamin U: A vitamin found in green vegetables. It is used in the treatment of peptic ulcers, colitis, and gastritis and has an effect on secretory, acid-forming, and enzymatic functions of the intestinal tract.Vicia faba: A plant species of the genus VICIA, family FABACEAE. The edible beans are well known but they cause FAVISM in some individuals with GLUCOSEPHOSPHATE DEHYDROGENASE DEFICIENCY. This plant contains vicine, convicine, Vicia lectins, unknown seed protein, AAP2 transport protein, and Vicia faba DNA-binding protein 1.Ranunculaceae: The buttercup plant family of the order Ranunculales, subclass Magnoliidae, class Magnoliopsida. The leaves are usually alternate and stalkless. The flowers usually have two to five free sepals and may be radially symmetrical or irregular.Plant Shoots: New immature growth of a plant including stem, leaves, tips of branches, and SEEDLINGS.Arabidopsis: A plant genus of the family BRASSICACEAE that contains ARABIDOPSIS PROTEINS and MADS DOMAIN PROTEINS. The species A. thaliana is used for experiments in classical plant genetics as well as molecular genetic studies in plant physiology, biochemistry, and development.Biological Transport: The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.Phytoplasma: A genus of minute bacteria in the family ACHOLEPLASMATACEAE that inhabit phloem sieve elements of infected PLANTS and cause symptoms such as yellowing, phyllody, and witches' brooms. Organisms lack a CELL WALL and thus are similar to MYCOPLASMA in animals. They are transmitted by over 100 species of INSECTS especially leafhoppers, planthoppers, and PSYLLIDS.Tobacco: A plant genus of the family SOLANACEAE. Members contain NICOTINE and other biologically active chemicals; its dried leaves are used for SMOKING.Verbascum: A plant genus of the family SCROPHULARIACEAE.Cucumis: A plant genus of the family CUCURBITACEAE, order Violales, subclass Dilleniidae best known for cucumber (CUCUMIS SATIVUS) and cantaloupe (CUCUMIS MELO). Watermelon is a different genus, CITRULLUS. Bitter melon may refer to MOMORDICA or this genus.Inflorescence: A cluster of FLOWERS (as opposed to a solitary flower) arranged on a main stem of a plant.Plant Diseases: Diseases of plants.Eucalyptus: A genus of trees of the Myrtaceae family, native to Australia, that yields gums, oils, and resins which are used as flavoring agents, astringents, and aromatics.Populus: A plant genus of the family SALICACEAE. Balm of Gilead is a common name used for P. candicans, or P. gileadensis, or P. jackii, and sometimes also used for ABIES BALSAMEA or for COMMIPHORA.Clethraceae: A plant family of the order Ericales, subclass Dilleniidae, class Magnoliopsida.Liquidambar: A plant genus of the family HAMAMELIDACEAE. The sap is a source of storax, which should not be confused with the similar named STYRAX genus.Solanum tuberosum: A plant species of the genus SOLANUM, family SOLANACEAE. The starchy roots are used as food. SOLANINE is found in green parts.Citrullus: A plant genus of the family CUCURBITACEAE known for the edible fruit.Hemiptera: A large order of insects characterized by having the mouth parts adapted to piercing or sucking. It is comprised of four suborders: HETEROPTERA, Auchenorrhyncha, Sternorrhyncha, and Coleorrhyncha.Plant Physiological Phenomena: The physiological processes, properties, and states characteristic of plants.Brassica napus: A plant species of the family BRASSICACEAE best known for the edible roots.