Underground stem
Encyclopedia
Underground stems are modified plant structures that derive from stem
tissue but exist under the soil
surface. Plants have two axes of growth, which can be best seen from 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 root
s. 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 bud
s where leaves and flowers arise at specific locations, while roots do not.
Plants use under ground stems to multiply their numbers by asexual reproduction
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
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
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 herbivore
s. 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.
A number of underground stems are consumed by people including; onion
, potato
, ginger
, yam
and taro
.
Plant 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 , conifer cones, roots, other stems etc. The internodes distance one node from another...
tissue but exist under the soil
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...
surface. Plants have two axes of growth, which can be best seen from seed
Seed
A seed 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...
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 root
Root
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 . Furthermore, a stem normally occurring below ground is not exceptional either...
s. 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 bud
Bud
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. Buds may be specialized to develop flowers or short shoots, or may have...
s 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
Asexual reproduction is a mode of reproduction by which offspring arise from a single parent, and inherit the genes of that parent only, it is reproduction which does not involve meiosis, ploidy reduction, or fertilization. A more stringent definition is agamogenesis which is reproduction without...
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
Dormancy is a period in an organism's life cycle when growth, development, and physical activity are temporarily stopped. This minimizes metabolic activity and therefore helps an organism to conserve energy. Dormancy tends to be closely associated with environmental conditions...
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
Grazing generally describes a type of feeding, in which a herbivore feeds on plants , and also on other multicellular autotrophs...
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 herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
s. 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:- BulbBulbA bulb is a short stem with fleshy leaves or leaf bases. The leaves often function as food storage organs during dormancy.A bulb's leaf bases, known as scales, generally do not support leaves, but contain food reserves to enable the plant to survive adverse conditions. At the center of the bulb is...
- Short, upright organ used by plants for food storage or reproduction, with specialized leaves modified into thick flesh scales. Tulips and Lilies. - CormCormA 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 ....
- Short, upright, hard or fleshy stems covered with thin, dry papery leaves. - RhizomeRhizomeIn botany and dendrology, a rhizome is a characteristically horizontal stem of a plant that is usually found underground, often sending out roots and shoots from its nodes...
- With reduced scale like leaves. The top can generate leafy stems while the bottom can produce roots. Iris. - StolonStolonIn biology, stolons are horizontal connections between organisms. They may be part of the organism, or of its skeleton; typically, animal stolons are external skeletons.-In botany:...
- 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". - TuberTuberTubers 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...
- 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
The onion , also known as the bulb onion, common onion and garden onion, is the most widely cultivated species of the genus Allium. The genus Allium also contains a number of other species variously referred to as onions and cultivated for food, such as the Japanese bunching onion The onion...
, potato
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...
, ginger
Ginger
Ginger is the rhizome of the plant Zingiber officinale, consumed as a delicacy, medicine, or spice. It lends its name to its genus and family . Other notable members of this plant family are turmeric, cardamom, and galangal....
, yam
Yam (vegetable)
Yam is the common name for some species in the genus Dioscorea . These are perennial herbaceous vines cultivated for the consumption of their starchy tubers in Africa, Asia, Latin America and Oceania...
and taro
Taro
Taro is a common name for the corms and tubers of several plants in the family Araceae . Of these, Colocasia esculenta is the most widely cultivated, and is the subject of this article. More specifically, this article describes the 'dasheen' form of taro; another variety is called eddoe.Taro is...
.