Any of the more than 250,000 species of angiosperms (division Magnoliophyta) having roots, stems, leaves, and well-developed conductive tissues (xylem and phloem). They are often differentiated from gymnosperms by their production of seeds within a closed chamber (the ovary) within the flower, but this distinction is not always clear-cut. The division is composed of two classes: monocots and dicots (seecotyledon). Monocots have flower parts in threes, scattered conducting strands in the stem, and usually prominent parallel veins in the leaves, and they lack a cambium. Dicots have flower parts in fours or fives, conducting strands arranged in a cylinder, a net-veined pattern in the leaves, and a cambium. Flowering plants reflect an immense diversity in habit, size, and form; they account for more than 300 families growing on every continent, including Antarctica. Flowering plants have adapted to almost every habitat. Most reproduce sexually by seeds via the specialized reproductive organs that are present in all flowers.