_pollen._ The dust or grains contained in the anther, which, falling on the stigma, grows and fertilizes the forming ovules. _pollination._ The transfer of pollen from the anther to the stigma. The transfer may be accomplished by wind, insects, birds, water (in the case of water plants), or by the natural falling of the pollen. _polypetalous_ (“many-petaled”). Said of a corolla with the petals not united. _polysepalous_ (“many-sepaled”). Said of a calyx with sepals not united. _pome._ An apple-like or pear-like or quince-like fruit, with a five-carpeled or en-carpeled “core.” _proterandrous._ Said of a flower when the anthers mature in advance of the pistils in the same flower. _proterogynous._ Said of a flower when its pistils mature before its anthers. _prothallus_ (“first thallus”). The minute leaf-like body or organ produced by the germination of a spore, in ferns and allied plants. It bears the sex organs. _protoplasm._ The living matter in plants. It is the living part of the cells, usually in a semi-fluid, translucent state. _pseud-annual._ A plant that is apparently annual, but which is carried over winter by a bulb, tuber, or similar body; as potato, onion. _pyxis._ A dry fruit or capsule in which the top comes off, like a cover to a jar. _raceme._ A simple (unbranched) cluster in which the flowers are on short pedicels and open from the base upwards. _raphe._ A ridge or elevation on some seeds caused by the seed-stalk and seed-coats growing together. _ray._ The elongated corolla-limb of some members of the Compositæ family. _receptive._ Said of a stigma when it is “ripe” or ready to receive the pollen. _regular flowers_ are those in which all the members of each series (as all the sepals, or all the petals, or all the stamens) are like each other in shape, size, and colour. _reinforced._ See _accessory fruits_. _respiration._ Breathing; manifest by oxygen taken in and carbon dioxide given off. _rhizome._ A rootstock; an underground root-like stem. It has joints, usually scales representing leaves, and is often thick and fleshy. _samara._ A key fruit, being an indehiscent (not opening) fruit provided with a wing or wings. _saprophyte._ A plant that lives on dead or decaying material. See _parasite_. _scape._ A flower-stem rising directly from the crown of the plant at the surface of the ground or near it. A scape may have bracts. _self-fertilization_ or _close-fertilization_ is fertilization by means of pollen produced in the same flower. _sepal._ One of the parts or leaves of the calyx. _septicidal._ A form of dehiscence or opening along the natural partitions of the capsule. _sessile._ Sitting; without a stem, as a leaf without petiole, or a flower without pedicel or peduncle. _shrub._ A low woody plant that does not have a distinct trunk. When a plant normally has a trunk, it is a tree.