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Malesia: The biogeographical region from Western Malaysia to New Britain, embracing the Malay Archipelago; it was formerly called Malaysia, but the name can no longer be used in this context, as it is now a political unit comprising the former Malaya, Sarawak and Sabah.

Male sterility: In flowering plants when the pollen is absent or non-functional.

Mass selection: A system of breeding in which seed from individuals selected on the basis of phenotype is composited and used to grow the next generation.

Meiosis: Nuclear divisions in which the diploid chromosome number is reduced of half that of the parent cell to give the haploid number, as in gametes.

Membranous: Thin, dry, flexible, parchmentlike.

Mericarp: One of the separate halves or parts of a fruit, as in Umbelliferae.

Meristem: Undifferentiated tissue of the growing point whose cells are capable of dividing and developing into various organs and tissues.

Mesocarp: The middle layer of the pericarp or fruit wall which is often fleshy or succulent.

Mesophyte: Average plant, often with broad leaves, suited to a fairly or continuously moist climate.

Micropyle: The minute opening between the integuments in an ovule through which the pollen-tube usually enters.

Midrib: The main vein of a leaf which is a continuation of the petiole.

Mitosis: The normal process of the division of somatic cells in which the chromosomes are duplicated longitudinally to give two daughter nuclei each having a chromosome complement equal to that of the original nucleus.

Monadelphous: Of stamens which are united into one group by their filaments.

Moniliform: Like a string of beads.

Monocarpic: Flowering and fruiting once and then dying.

Monochasium: A cyme reduced to a single flower in each axis.

Monocotyledon: Angiosperms having a single cotyledon or seed-leaf.

Monoecious: When the male and female flowers are separate, but borne on the same plant.

Monoembryonic: A seed with a single embryo which is usually of gametic origin.

Monophyletic: Derived from a single ancestral line.

Monopodial: Of a primary axis which continues its original line of growth from the same apical meristem to produce successive lateral branches.

Monotypic: Of a genus composed of a single species.

Mucronate: Ending abruptly in a short stiff point.

Multiple alleles: A series of alleles or alternative forms of a gene.

Multiple genes: Two or more independent pairs of genes which produce complementary or cumulative effects upon a single character of the phenotype.

Muricate: Rough with short firm projections.

Mutation: A sudden variation in the hereditary material of a cell.

Mycorrhiza: A symbiotic association of roots with a fungus which may form a layer outside the root (ectotrophic) or within the outer tissues (endotrophic).

Nectary: A nectar-secreting gland.

Nerve: A strand of strengthening or conducting tissue running through a leaf, which starts from the midrib and diverges or branches throughout the blade.

Node: The point on the stem or branch at which a leaf or branch is borne.

Nucellar embryo: An embryo developed from the tissue of the nucellus and consequently of the same genotype as the female parent.

Nucellus: The nutritive tissue in an ovule.

Nut: Properly a one-seeded indehiscent fruit with a hard dry pericarp or shell.

Nutlet: A little nut.

Obcordate: Deeply notched at the apex.

Oblanceolate: Much longer than broad and with the greatest width above the middle.

Oblique: Slanting; unequal-sided.

Oblong: Longer than broad with the sides parallel or almost so.

Obovate: Egg-shaped with the terminal half broader than the basal half.

Obtuse: Blunt or rounded at the end.

Ochrea: A tubular stipule sheathing the stem.

Open-pollination: Pollination without control so that the male parent is not known.

Opposite: Of leaves and branches when two are borne at the same node on opposite sides of the stem.

Orbicular: Flat with a more or less circular outline.

Orthotropic: Vertical growth; tendency to elongate vertically.

Outcross: Cross-pollination, usually by natural means, with plants differing in genetic constitution.

Ovary: That part of the pistil, usually the enlarged base, which contains the ovules and eventually becomes the fruit.

Ovate: Egg-shaped; a flat surface which is scarcely twice as long as broad with the widest portion below the middle.

Ovoid: A solid object which is egg-shaped (ovate) in section.

Ovule: A structure containing the egg and developing into the seed after fertilization.

Palea: The upper of the two bracts enclosing each floret in a grass spikelet.

Palmate: Lobed or divided like the palm of the hand.

Palmatifid: Cut about half way down in a palmate manner.

Pandurate: Fiddle-shaped.

Panicle: An indeterminate branching racemose inflorescence with stalked flowers.

Paniculate: Resembling a panicle.

Papillose: Covered with minute nipple-like protuberances.

Pappus: The ring of hairs or scales round the tip of the fruit, as in Compositae.

Parietal: When ovules are attached to the inner surface of the walls of a one-celled syncarpous ovary.

Paripinnate: A pinnate leaf without the odd terminal leaflet.

Parthenocarpic: The production of fruit without pollination.

Parhenogenic: The development of an individual from a gamete without fertilization.

Parthe: Nearly, but not quite to the base.

Pectinade: Comb-like.

Pedicel: Stalk of each individual flower of an inflorescence.

Peduncle: The stalk on an inflorescence or partial inflorescence.

Pellucid: Translucent.

Peltate: Of a leaf with the stalk attached to the under surface, not at the edge.

Pendulous: Drooping; hanging down.

Pentaploid: Having five sets of chromosomes (5n).

Perennial: Living from year to year and usually flowering each year.

Perfect flower: A flower possessing both male and female organs.

Perfoliate: Of a sessile leaf or bract whose base completely surrounds the stem.

Perianth: The floral leaves as a whole, including both sepals and petals if both are present.

Pericarp: The wall of the ripened ovary or fruit wall of which the layers may be fused into one, or be more or less divisible into exocarp, mesocarp and endocarp.

Perigynous: When the sepals, petals and stamens are carried up around the ovary, but are not attached to it.

Perisperm: The nutritive tissue of some seeds derived Irons the nucellus.

Persistent: Remaining attached; not falling off.

Petal: A member of the inner series of perianth segments which are often brightly coloured.

Petaloid: Petal-like.

Petiole: The stalk of a leaf.

Petiolule: The stalk of a leaflet.

Phenotype: The physical or external appearance of an organism as distinguished from its genetic constitution (genotype); a group of organisms with similar physical or external make-up.

Phyllode: A flattened petiole taking on the form and function of a leaf.

Phyllotaxy: The arrangement of leaves or floral parts on their axis.

Physiological races: Pathogens of the same species and variety, which are structurally similar, but which differ in physiological and pathological characteristics.

Pilose: Hairy with rather long soft hairs.

Pinna, p1. pinnae: A primary division or leaflet of a pinnate leaf.

Pinnate: A compound leaf with the leaflets arranged along each side of a common rachis.

Pinnatifid: With the margin pinnately cleft.

Pinnatilobed: Pinnately divided to about half-way to the midrib.

Pinnule: The secondary or tertiary leaflet of a leaf which is twice or thrice pinnate.

Pistil: The female part of a flower (gynoecium) consisting, when complete, of ovary, styles and stigmas, of one or more carpels.

Pistillate: A unisexual flower with pistil, but no stamens.

Placenta: The part of the ovary to which the ovules are attached.

Placentation: The position of the placentae in the ovary.

Plagiotropic: Having the lateral branches inclined away from the vertical line.

Plasmagene: A cytoplasmic-borne unit of heredity.

Plicate: Folded like a fan.

Plumose: Featherlike with fine hairs, as on the sides of some bristles.

Plumule: The primary bud of an embryo or germinating seed.

Pod: An uncritical term for a dry dehiscent fruit.

Polar nuclei: Two of the nuclei of the embryo sac which unite with the second sperm from the pollen in a triple fusion, giving rise to the endosperm, which is thus triploid.

Pollen: Spores or grains borne by the anthers containing the male element (gametophyte).

Pollen tube: The tube developing from the germinating pollen grain through which the germ cells pass to reach the ovule.

Pollination: The transfer of pollen from the dehiscing anther to the receptive stigma.

Pollinia: Regularly shaped masses of pollen formed by the cohesion of a large number of pollen grains, as in orchids.

Polycross: An isolated group of plants or clones arranged to facilitate random inter-pollination.

Polyembryony: The production of two or more embryos within an ovule.

Polygamous: With unisexual and bisexual flowers in the same plant.

Polymorphic: Very variable in habit or some morphological feature; represented by two or more forms.

Polypetalous: With a corolla of separate petals.

Polyploid: An organism with more than two sets (genomes) of chromosomes in its somatic cells.

Pome: A fruit in which the seeds are surrounded by a tough but not woody layer, derived from the inner part of the fruit wall, the whole fused with the deeply cup-shaped fleshy receptacle, e.g., apple.

Precocious: Appearing or developing early.

Prickle: A sharp relatively stout outgrowth from the outer layers.

Procumbent: Lying loosely along the surface of the ground.

Proliferous: Bearing adventitious buds on the leaves or in the flowers, which can root and form separate plants.

Protandrous: Stamens shedding pollen before the stigma is receptive.

Protogynous: When the stigma is receptive before the pollen is shed.

Pseudobulb: A thickened or bulbiform stem, as of certain orchids.

Puberulous: Minutely pubescent.

Pubescent: Covered with soft short hairs.

Panetate: Marked with dots or translucent glands.

Pure line: A strain in which all members have descended by self-fertilization from a single homozygous individual.

Pyrene: A nutlet or kernel; the stone of a drupe or similar fruit.