Botany - Structure

Structure

Plant anatomy is the study of the internal cells and tissues of a plant; whereas plant morphology is the study of their general and external form.

Understanding the structure and function of cells is fundamental to all of the biological sciences. All organisms have cells, the cell types are unique and their nuclei store most of the DNA. Cell biology studies their structural and physiological properties. This includes responses to stimuli, reproduction, and development on the macroscopic scale, microscopic scale, and molecular level. The similarities and differences between the function of a cell are quite varied. Plant cells are eukaryotic, ie, have a membrane-encased nucleus that carries genetic material. With rare exceptions, plant cells also have a central vacuole, cytoplasm, cytosol, dictyosomes, endoplasmic reticulum, microbodies, microfilaments, microtubules, mitochondria, plasma membrane, plastids, protoplasm, ribosomes, storage products, and a cell wall. Cells divide by processes known as karyokinesis and cytokinesis.

The body of a plant contains three basic parts: roots, stems, and leaves. Roots anchor it to the ground, gather water and mineral nutrients from the soil, and produce hormones. Roots which spread out close to the surface, such as those of willows, can produce shoots and ultimately new plants. Fleshy taproots, such as those of beets and carrots, store carbohydrates. Stems provide support to the leaves and store nutrients. Leaves gather sunlight and begin photosynthesis. Large, flat, flexible, green leaves are called foliage leaves. Gymnosperms are seed-producing plants which have open seeds, such as conifers, cycads, Ginkgo, and gnetophyta. Angiosperms are seed-producing plants that produce flowers, having enclosed seeds. Some of the gymnosperms became the ancestors of the angiosperms. Woody plants, such as azaleas and oaks, undergo a secondary growth phase resulting in two additional types of tissues: wood (secondary xylem) and bark (secondary phloem and cork). All gymnosperms and many angiosperms are woody plants. Some plants reproduce sexually, some asexually, and some via both means.