Flowering plants (angiosperms) have ovules and seeds enclosed within carpels. The term angiosperms is derived from two Greek words angeion, meaning “vessel”, and sperma, meaning “seed”. The vessel is the carpels that become ovaries then become fruits. There is divided into two classes which are dicots (Magnoliopsida) and monocots (Liliopsida) and there is on;y one phylum of flowering plants (Magnoliophyta). The ancestors of flowering plants are believed to have evolved from gymnosperm. Flowering plants produce two kinds of spores which are heterosporous. Its gametophytes develop in separate structures. The female gametophyte (megagametophyte) develops in the ovule. Megagametophyte is surround by integuments, which later become a seed coat. Pollen grains developed in anthers become male gametophytes. Pollination of angiosperm is brought about by insects, wind, and other agents. After pollination, a pollen tube grow from a pollen grain to the female gametophyte. The tube nucleus remains at its tip, and the generative cell divides, producing two sperm nuclei. Following the contents discharge of the pollen tube into the female gametophyte, a sperm unites with the egg, forming a zygote. The other sperm simultaneously unites with the two central cell nuclei, forming 3x endosperm. The nutritive endosperm tissue may become part of the seed or absorbed by the seed’s embryo. Some flowering plants produce 5x, 9x, or 15x endosperm tissue due to variations in how a female gametophyte develops. Bee-pollinated flowers are sweet and fragrant and always to be blue or yellow in color. Beetle-pollinated flowers tend to have stronger odors and are usually white or dull in color. Some fly-pollinated flowers expel foul odors. Moth-pollinated flowers usually white or yellow in color. Bird-pollinated flowers are usually bright red or yellow and have much nectar but little odor. Most orchids produce pollen grains in pollinia that stick onto parts of visiting insects. Herbaria are fundamentally collection of dried, pressed, or preserved plants, fungi, and algae ordered so that specific specimens may be readily located. Properly preserved plants may last for hundreds of years. A plant to be pressed is placed in a plant press between sheets of newspaper and absorbent material. Dry specimens are mounted to sheets of high-quality paper, with a label giving collection information. Plant parts may be pressed for art work, place mats, and so on. Flowers may be preserved 3D. Collectors should try to limit their future collecting to photographs as much as possible because so many plants are now on rare and endangered species lists.