D.

=Dew=, _n._ The moisture of the air when condensed on any cold surface. Dew does not _fall_; it is formed wherever moisture in the air comes in contact with a substance colder than the air. Hence there may be dew on the under as well as the upper side of a leaf.

=Dissolve=, _v._ L. _dis_, apart, _solvere_, loose; to separate the solid particles of a body in a liquid; to melt. Sugar dissolves in water.

=Double flowers=, _n._ All those whose petals are numerous. Sometimes the stamens are changed into petals, as in double roses, and sometimes even the pistils have become petals.

E.

=Evaporation=, _n._ The conversion of a solid or liquid by heat into vapor. Most often used in reference to the conversion of water into vapor. The warm air of summer causes a rapid evaporation of water from the leaves of plants.

F.

=Fayal=, _n._ One of the Azores Islands, west of Portugal.

=Ferns=, _n._ A division of flowerless plants.

=Fertilize=, _v._ L. _fertilis_, fruitful; to make fruitful or productive, in the flower, by introducing the pollen to the ovule, enabling them in union to become a seed.

=Filament=, _n._ L. _filum_, a thread; the stem of an anther, often thread-like in form, though it varies greatly; any thread-like part.

=Flower=, _n._ L. _flos_, a flower; the part of a plant consisting of pistil, stamens, corolla, and calyx. Sometimes the corolla is wanting; sometimes both calyx and corolla are wanting. Since pistils and stamens are the most important part of the flower, an organ containing them only is called a flower. Sometimes a flower consists of only stamens or only pistils, as in some kinds of maple.

=Force pump=, _n._ A pump in which a liquid is moved by pressure behind instead of being lifted, as is the case in the ordinary pump.

=Fossil=, _n._ Animal or vegetable forms which have been long buried in the earth and so preserved; the _forms_ or traces of animal or vegetable structures which have been preserved in rock.

=Fruit=, _n._ The matured ovary and all it contains or is incorporated with. Sometimes the calyx forms part of the fruit, as in the apple.

G.

=Gamopetalous=, _a._ From two Greek words meaning “marriage” and “leaf” or “petal”; having the petals united or grown together. Where a flower has the corolla in the form of a tube it is called gamopetalous. Several petals are believed to be united into one piece.

=Geranium=, _n._ From a Greek word meaning “crane’s bill”; the name of a plant, so called because of the long, projecting beak of the seed-vessel.

=Gland=, _n._ Certain cells upon or near the surface of a plant that secrete, or take from the sap, certain substances. The nectary is a gland that secretes a sweet juice.

=Great pyramids of Egypt=, _n._ Three large pyramids at Ghizeh, near Cairo, in Egypt. The largest one is the largest work of man’s hands in the world. The pyramids are very interesting structures, and are probably the tombs of the ancient rulers of Egypt.

=Guard cells=, _n._ The curved cells that guard the entrance to the stomata, or breathing pores, of leaves.

H.

=Hairs=, _n._ Fine, thread-like outgrowths from the skin of plants or animals.

=Halberd-shaped=, _a._ Shaped like a halberd, or old-time battle-ax. The bases of certain leaves are called halberd-shaped from their form.

=Hawthorne=, _n._ A small tree with thorny stems. The fruit consists of small bright red berries called “haws.”

=Heart=, _n._ The principal organ for the circulation of the blood in man and other animals.

=Hercules=, _n._ In Greek and Roman mythology, a mighty hero, the god of strength and courage. He performed many feats of strength, chief among which are those known as the twelve labors of Hercules.

=Honeycomb cells=, _n._ The wax cells made by bees for storing the honey.

=Hyacinth=, _n._ The name of an early spring flower; also of a precious stone.

=Hydrogen=, _n._ From two Greek words meaning “water producing.” It is a very light, invisible gas, and when chemically united to oxygen, two parts of hydrogen to one of oxygen, the result is water.