Underground stems are modified plant structures that derive from stem A stem is one of two main structural axes of a vascular plant. The stem is normally divided into nodes and internodes, the nodes hold buds which grow into one or more leaves, inflorescence , cones or other stems etc. The internodes distance one node from another. The term shoots is often confused with stems; shoots generally refer to new fresh tissue but exist under the soil Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics. It is composed of particles of broken rock that have been altered by chemical and environmental processes that include weathering and surface. Plants have two axes of growth, which can be best seen from seed A seed ( /ˈsiːd/ ) is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant. The formation of the seed completes the process of reproduction in seed germination and growth. Seedlings develop two structures or axes of growth, one that develops upward out of the soil, called stems, and structures that develop downward which are called roots In vascular plants, the root is the organ of a plant that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial or aerating (growing up above the ground or especially above water). Furthermore, a stem normally occurring below ground is not exceptional either (see rhizome). So, it is. The roots are modified to have root hairs and branch indiscriminately with cells that take in water and nutrients, while the stems are modified to move water and nutrients to and from the leaves and flowers. Stems have nodes with buds In botany, a bud is an undeveloped or embryonic shoot and normally occurs in the axil of a leaf or at the tip of the stem. Once formed, a bud may remain for some time in a dormant condition, or it may form a shoot immediately where leaves and flowers arise at specific locations, while roots do not. Plants use under ground stems to multiply their numbers by asexual reproduction Asexual reproduction is reproduction which does not involve meiosis, ploidy reduction, or fertilization. Only one parent is involved in asexual reproduction. A more stringent definition is agamogenesis which refers to reproduction without the fusion of gametes. Asexual reproduction is the primary form of reproduction for single-celled organisms and to survive from one year to the next, usually over a period of dormancy. Plants produce these modified stems so they can survive a cold or dry period which normally is a period of inactive growth, and when the cold or dry period is over the plants begin new growth from the underground stems. Being underground protects the stems from the elements during the dormancy Dormancy is a period in an organism's life cycle when growth, development, and physical activity is temporarily stopped. This minimizes metabolic activity and therefore helps an organism to conserve energy. Dormancy tends to be closely associated with environmental conditions. Organisms can synchronize entry to a dormant phase with their period, such as freezing and thawing in winter or extreme heat and drought in summer or fire. They can also protect plants from heavy grazing Grazing generally describes a type of predation in which a herbivore feeds on plants , and also on other multicellular autotrophs (such as algae). Grazing differs from true predation because the organism being eaten is not killed, and it differs from parasitism as the two organisms do not live together, nor is the grazer necessarily so limited in pressure from animals, the plant might be eaten to the ground but new growth can occur from below ground that can not be reached by the herbivores Herbivores are animals that are adapted to eat plants. Herbivory is a form of predation in which an organism consumes principally autotrophs[page needed] such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in general are known as primary consumers. A number of weedy species use underground stems to spread and colonize large areas since the stems do not have to be supported or strong, less energy and resources are needed to produce these stems, often these weeds have more mass under ground than above ground.
Types of underground stems
Different forms of underground stems include:
- Bulb A bulb is a short stem with fleshy leaves or leaf bases. The leaves often function as food storage organs during dormancy - Short, upright organ used by plants for food storage or reproduction, with specialized leaves modified into thick flesh scales. Tulips and Lilies.
- Corm A corm is a short, vertical, swollen underground plant stem that serves as a storage organ used by some plants to survive winter or other adverse conditions such as summer drought and heat (estivation). A corm consists of one or more internodes with at least one growing point, with protective leaves modified into skins or tunics. The thin tunic - Short, upright, hard or fleshy stems covered with thin, dry papery leaves.
- Rhizome In botany, a rhizome is a characteristically horizontal stem of a plant that is usually found underground, often sending out roots and shoots from its nodes. Rhizomes may also be referred to as creeping rootstalks or rootstocks - With reduced scale like leaves. The top can generate leafy stems while the bottom can produce roots. Iris.
- Stolon In biology, stolons are horizontal connections between organisms. They may be part of the organism, or of its skeleton; typically, animal stolons are external skeletons - Horizontal stems that run at or just below the soil surface with nodes that root and long internodes, the ends produce new plants. When above ground they are called "runners".
- Tuber Tubers are various types of modified plant structures that are enlarged to store nutrients. They are used by plants to survive the winter or dry months and provide energy and nutrients for regrowth during the next growing season and they are a means of asexual reproduction. Two different groups of tubers are: stem tubers, and root tubers - An enlarged fleshy end of a stem, generally from rhizomes but often also referring to thickened roots too.
A number of underground stems are consumed by people including; onion Onion is a term used for many plants in the genus Allium. They are known by the common name "onion" but, used without qualifiers, it usually refers to Allium cepa. Allium cepa is also known as the "garden onion" or "bulb" onion. Above ground, the onion shows only a single vertical shoot; the bulb grows underground,, potato The potato is a starchy, tuberous crop from the perennial Solanum tuberosum of the Solanaceae family . The word potato may refer to the plant itself as well as the edible tuber. In the region of the Andes, there are some other closely related cultivated potato species. Despite being first introduced outside the Andes region four centuries ago,, ginger Ginger is a tuber that is consumed whole as a delicacy, medicine, or herb. It is the rhizome of the plant Zingiber officinale. It lends its name to its genus and family . Other notable members of this plant family are turmeric, cardamom, and galangal and taro Taro is a common name for the corms and tubers of several genera of the family Araceae The name includes species of Colocasia spp (dasheen, taro, cocoyam, eddoe) Alocasia spp (giant taro), Amorphophallus campanulatus (Roxb) (elephant yam) and Crytosperma chamissons (Shott) and the tropical American Xanthosoma sagittifolim (Shott). Of all the.
