Most plants, from the smallest moss to the tallest tree, are characterized by the same basic plant parts: roots which pull up nutrients and water from underground; stems and leaves, which engage in photosynthesis, converting carbon dioxide, water and various other nutrients in the presence of sunlight to starches that feed the plant, releasing oxygen as a by-product; and flowers and fruits, which are the plant's reproductive organs.
Roots and Tubers
Roots are the underground portion of a plant, which absorbs nutrients and water from the soil, and anchors the plant firmly to the ground, supporting it's above-ground growth. A primary root is the first root to develop from a seed embryo and grow straight down. In some plants this develops into a taproot, a single large dominant vertical root like that one that makes dandelions hard to dig out of your lawn, or which forms the edible part of carrots, parsnips, and radishes. Secondary roots are fibrous root, and they develop after the primary root. Bulbs are modified roots that store plant energy over the dormant season. Corms and rhizomes are technically stems, but spread horizontally underground in spreading plant masses like lily of the valley or irises.
Leaves and Stems
Stems support flowers, fruit and leaves, and can be soft and twining (as in vines), sturdy, but still green and vegetative (as in flowers), or woody, ranging from the tough stems of sage to strong tree trunks. The phloem and xylem of a stem act as the plant's vascular system, carrying water and nutrients to leaves and flowers, while cell division and growth occurs in the cambium.
Leaves are attached to the stems by a petiole and typically grow as a flat blade on either side of a midrib or distinct center vein. Leaves absorb sunlight through their upper surfaces and take in carbon dioxide through stoma, or openings, in their lower surfaces, then engage in the process of photosynthesis.
Leaf shapes are described as oval, lanceolate, cordate, elliptical, or linear, and may be simple (singular) or compound (multiple leaves on a stem, such as walnut leaves). Leaves may have sawtooth edges referred to as "pinnate," or may be lobed or "palmate" such as a poison ivy or maple leaf.
Flowers and Fruit
Flowers are portions of a plant designed to attract pollinators such as birds and bees. The flower bud is protected by a calyx comprised of many sepals--green, sturdy leaf-like petals. Colorful and often fragrant petals are arrayed in a corolla, the shape of which varies depending on the species. The pistol is the female organ of the plant, and the stamen--a stem bearing a tip of pollen--is the male portion. Perfect flowers contain all male and female parts in one flower, while dioecious plants have separate male and female plants, and monoecious plants have separate male and female flowers on the same plant.
Fruit develops from the pollinated flower and is the portion of the plant which contains the seeds.