A storage organ is a part of a plant specifically modified for storage of energy
(generally in the form of
carbohydrate
In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or ma ...
s) or water. Storage organs often grow underground, where they are better protected from attack by
herbivore
A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...
s. Plants that have an underground storage organ are called geophytes in the
Raunkiær plant life-form classification system.
[; reprinted (1977) in ''History of ecology'' series, New York: Arno Press, ] Storage organs often, but not always, act as
perennating organ
A perennial plant or simply perennial is a plant that lives more than two years. The term (''wikt:per-#Prefix, per-'' + ''wikt:-ennial#Suffix, -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annual pl ...
s which enable plants to survive adverse conditions (such as cold, excessive heat, lack of light or drought).
Relationship to perennating organ
Storage organs may act as
perennating organ
A perennial plant or simply perennial is a plant that lives more than two years. The term (''wikt:per-#Prefix, per-'' + ''wikt:-ennial#Suffix, -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annual pl ...
s ('perennating' as in
perennial
A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...
, meaning "through the year", used in the sense of continuing beyond the year and in due course lasting for multiple years). These are used by plants to survive adverse periods in the plant's life-cycle (e.g. caused by cold, excessive heat, lack of light or drought). During these periods, parts of the plant die and then when conditions become favourable again, re-growth occurs from
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 a stem. Once formed, a bud may remain for some time in a dormant condition, or it may form a shoot immediately. Buds may be specia ...
in the perennating organs. For example, geophytes growing in woodland under deciduous trees (e.g.
bluebells,
trilliums) die back to underground storage organs during summer when tree leaf cover restricts light and water is less available.
However, perennating organs need not be storage organs. After losing their leaves, deciduous trees grow them again from 'resting buds', which are the perennating organs of phanerophytes in the
Raunkiær classification, but which do not specifically act as storage organs. Equally, storage organs need not be perennating organs. Many
succulents
In botany, succulent plants, also known as succulents, are plants with parts that are thickened, fleshy, and engorged, usually to retain water in arid climates or soil conditions. The word ''succulent'' comes from the Latin word ''sucus'', meani ...
have leaves adapted for water storage, which they retain in adverse conditions.
Underground storage organ
In common parlance, underground storage organs may be generically called roots,
tuber
Tubers are a type of enlarged structure used as storage organs for nutrients in some plants. They are used for the plant's perennation (survival of the winter or dry months), to provide energy and nutrients for regrowth during the next growing ...
s, or bulbs, but to the
botanist
Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek wo ...
there is more specific technical
nomenclature
Nomenclature (, ) is a system of names or terms, or the rules for forming these terms in a particular field of arts or sciences. The principles of naming vary from the relatively informal naming conventions, conventions of everyday speech to the i ...
:
* True
root
In vascular plants, the roots are the organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often below the sur ...
s:
** Storage
taproot
A taproot is a large, central, and dominant root from which other roots sprout laterally. Typically a taproot is somewhat straight and very thick, is tapering in shape, and grows directly downward. In some plants, such as the carrot, the taproo ...
— e.g. carrot
**
Tuberous root
Tubers are a type of enlarged structure used as storage organs for nutrients in some plants. They are used for the plant's perennation (survival of the winter or dry months), to provide energy and nutrients for regrowth during the next growing ...
or root tuber – e.g. ''
Dahlia
Dahlia (, ) is a genus of bushy, tuberous, herbaceous perennial plants native to Mexico and Central America. A member of the Asteraceae (former name: Compositae) family of dicotyledonous plants, its garden relatives thus include the sunflower, ...
''
* Modified
stem
Stem or STEM may refer to:
Plant structures
* Plant stem, a plant's aboveground axis, made of vascular tissue, off which leaves and flowers hang
* Stipe (botany), a stalk to support some other structure
* Stipe (mycology), the stem of a mushro ...
s:
**
Bulb
In botany, a bulb is structurally a short stem with fleshy leaves or leaf basesBell, A.D. 1997. ''Plant form: an illustrated guide to flowering plant morphology''. Oxford University Press, Oxford, U.K. that function as food storage organs duri ...
(a short stem that produces fleshy scale leaves or modified leaf bases) — e.g. ''
Lilium
''Lilium'' () is a genus of herbaceous flowering plants growing from bulbs, all with large prominent flowers. They are the true lilies. Lilies are a group of flowering plants which are important in culture and literature in much of the world. M ...
'', ''
Narcissus
Narcissus may refer to:
Biology
* ''Narcissus'' (plant), a genus containing daffodils and others
People
* Narcissus (mythology), Greek mythological character
* Narcissus (wrestler) (2nd century), assassin of the Roman emperor Commodus
* Tiberiu ...
'', onion
**
Caudex
A caudex (plural: caudices) of a plant is a stem, but the term is also used to mean a rootstock and particularly a basal stem structure from which new growth arises.pages 456 and 695
In the strict sense of the term, meaning a stem, "caudex" is m ...
— e.g. ''
Adenium
''Adenium'' is a genus of flowering plants in the family Apocynaceae first described as a genus in 1819. It is native to Africa and the Arabian Peninsula.
Cultivation and uses
''Adenium obesum'' is grown as a houseplant in temperate and tropica ...
'' (desert-rose)
**
Corm
A corm, bulbo-tuber, or bulbotuber is a short, vertical, swollen underground plant stem that serves as a storage organ that some plants use to survive winter or other adverse conditions such as summer drought and heat (perennation).
The word ' ...
— e.g. ''
Crocus
''Crocus'' (; plural: crocuses or croci) is a genus of seasonal flowering plants in the family Iridaceae (iris family) comprising about 100 species of perennials growing from corms. They are low growing plants, whose flower stems remain undergro ...
''
**
Pseudobulb
The pseudobulb is a storage organ found in many epiphytic and terrestrial sympodial orchids. It is derived from a thickening of the part of a stem between leaf nodes and may be composed of just one internode or several, termed heteroblastic and ...
— e.g. ''
Pleione'' (windowsill orchid)
**
Rhizome
In botany and dendrology, a rhizome (; , ) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow hori ...
— e.g. ''
Iris pseudacorus
''Iris pseudacorus'', the yellow flag, yellow iris, or water flag, is a species of flowering plant in the family Iridaceae. It is native to Europe, western Asia and northwest Africa. Its specific epithet ''pseudacorus'' means "false acorus", re ...
'' (yellow flag iris)
**
Stem tuber
Tubers are a type of enlarged structure used as storage organs for nutrients in some plants. They are used for the plant's perennation (survival of the winter or dry months), to provide energy and nutrients for regrowth during the next growing ...
— e.g. ''
Zantedeschia
''Zantedeschia'' is a genus of eight species of herbaceous, perennial, flowering plants in the family Araceae, native to southern Africa from South Africa north to Malawi. The genus has been introduced on all continents except Antarctica. Commo ...
'' (arum lily), potato
** Trophopod (the persistent
petiole base of several fern genera) — e.g. ''
Diplazium
''Diplazium'' is a genus of ferns that specifically includes the approximately 400 known species of twinsorus ferns. The Greek root is ''diplazein'' meaning ''double'': the indusia in this genus lie on both sides of the vein. These ferns were ...
'', ''
Onoclea sensibilis
''Onoclea sensibilis'', the sensitive fern, also known as the bead fern, is a coarse-textured, medium to large-sized deciduous perennial fern. The name comes from its sensitivity to frost, the fronds dying quickly when first touched by it. It is ...
''
* Others:
** Storage
hypocotyl
The hypocotyl (short for "hypocotyledonous stem", meaning "below seed leaf") is the stem of a germinating seedling, found below the cotyledons (seed leaves) and above the radicle (root).
Eudicots
As the plant embryo grows at germination, it send ...
(the stem of a seedling) — sometimes called a
tuber
Tubers are a type of enlarged structure used as storage organs for nutrients in some plants. They are used for the plant's perennation (survival of the winter or dry months), to provide energy and nutrients for regrowth during the next growing ...
, as in ''
Cyclamen
''Cyclamen'' ( or ) is a genus of 23 species of perennial flowering plants in the family Primulaceae. ''Cyclamen'' species are native to Europe and the Mediterranean Basin east to the Caucasus and Iran, with one species in Somalia. They grow ...
''
Some of the above, particularly pseudobulbs and caudices, may occur wholly or partially above ground. Intermediates and combinations of the above are also found, making classification difficult. As an example of an intermediate, the tuber of ''Cyclamen'' arises from the stem of the seedling, which forms the junction of the roots and stem of the mature plant. In some species (e.g. ''
Cyclamen coum
''Cyclamen coum'', the eastern sowbread, is a species of flowering plant in the family Primulaceae. It is a tuberous herbaceous perennial, growing to , with rounded heart-shaped leaves and pink shell-shaped flowers with darker coloration at the ...
'') roots come from the bottom of the tuber, suggesting that it is a stem tuber; in others (e.g. ''
Cyclamen hederifolium
''Cyclamen hederifolium'', the ivy-leaved cyclamen or sowbread, is a species of flowering plant in the family Primulaceae. This widespread cyclamen species is widely cultivated and among the most hardy and vigorous in oceanic climates. It is na ...
'') roots come largely from the top of the tuber, suggesting that it is a root tuber. As an example of a combination, juno irises have both bulbs and storage roots.
Underground storage organs used for food may be generically called
root vegetable
Root vegetables are underground plant parts eaten by humans as food. Although botany distinguishes true roots (such as taproots and tuberous roots) from non-roots (such as bulbs, corms, rhizomes, and tubers, although some contain both hypocotyl a ...
s, although this phrase should not be taken to imply that the class only includes true roots.
Other storage organs
Succulent
In botany, succulent plants, also known as succulents, are plants with parts that are thickened, fleshy, and engorged, usually to retain water in arid climates or soil conditions. The word ''succulent'' comes from the Latin word ''sucus'', meani ...
s are plants which are adapted to withstand periods of drought by their ability to store moisture in specialized storage organs.
[Information in this section taken from , pp. 75–6]
* Leaf succulents store water in their leaves, which are thus thickened, fleshy and typically covered with a waxy coating or fine hairs to reduce evaporation. They may also contain mucilaginous compounds. Some leaf succulents have leaves which are distributed along the stem in a similar fashion to non-succulent species (e.g. ''
Crassula
''Crassula'' is a genus of succulent plants containing about 200 accepted species, including the popular jade plant (''Crassula ovata''). They are members of the stonecrop family (Crassulaceae) and are native to many parts of the globe, but cult ...
'', ''
Kalanchoe
''Kalanchoe'' , also written ''Kalanchöe'' or ''Kalanchoë'', is a genus of about 125 species of tropical, succulent plants in the stonecrop family Crassulaceae, mainly native to Madagascar and tropical Africa. A ''Kalanchoe'' species was one ...
''); their stems may also be succulent. In others, the leaves are more compact, forming a rosette (e.g. ''
Echeveria
''Echeveria'' is a large genus of flowering plants in the family Crassulaceae, native to semi-desert areas of Central America, Mexico and northwestern South America.
Description
Plants may be evergreen or deciduous. Flowers on short stalks (cyme ...
'', ''
Aloe
''Aloe'' (; also written ''Aloë'') is a genus containing over 650 species of flowering succulent plants.WFO (2022): Aloe L. Published on the Internet;http://www.worldfloraonline.org/taxon/wfo-4000001341. Accessed on: 06 Nov 2022 The most wid ...
''). Pebble-plants or living stones (e.g. ''
Lithops
''Lithops'' is a genus of succulent plants in the ice plant family, Aizoaceae. Members of the genus are native to southern Africa. The name is derived from the Ancient Greek words () 'stone' and () 'face', referring to the stone-like appearanc ...
'', ''
Conophytum
''Conophytum'' is a genus of South African and Namibian succulent plants that belong to the family Aizoaceae. The name is derived from the Latin ''conus'' (cone) and Greek ''phytum'' (plant). The plants are also known as knopies (buttons in ...
'') have reduced their leaves to just two, forming a fleshy body, only the top of which may be visible above ground.
![Ferocactus pilosus1](https://upload.wikimedia.org/wikipedia/commons/5/55/Ferocactus_pilosus1.jpg)
*
Stem succulent
Stem succulents are fleshy succulent columnar shaped plants which conduct photosynthesis mainly through their stems rather than their leaves.Frerea indica, a Stem Succulent CAM Plant with Deciduous C₃ Leaves, Otto L. Lange and Margit Zuber, Oeco ...
s are generally either leafless or have leaves which can be quickly shed in the event of drought. Photosynthesis is then taken over by the stems. As with leaf succulents, stems may be covered with a waxy coating or fine hairs to reduce evaporation. The ribbed bodies of
cacti
A cactus (, or less commonly, cactus) is a member of the plant family Cactaceae, a family comprising about 127 genera with some 1750 known species of the order Caryophyllales. The word ''cactus'' derives, through Latin, from the Ancient Greek ...
may be an adaption to allow shrinkage and expansion with the amount of water stored. Plants of the same general form as cacti are found in other families (e.g. ''
Euphorbia canariensis
''Euphorbia canariensis'', commonly known as the Canary Island spurge, Hercules club or in Spanish ''cardón'', is a succulent member of the genus ''Euphorbia'' and family Euphorbiaceae endemic to the Canary Islands. It is the plant symbol of t ...
'' (family
Euphorbiaceae
Euphorbiaceae, the spurge family, is a large family of flowering plants. In English, they are also commonly called euphorbias, which is also the name of a genus in the family. Most spurges, such as ''Euphorbia paralias'', are herbs, but some, e ...
), ''
Stapelia
''Stapelia'' is a genus of low-growing, spineless, stem succulent plants, predominantly from South Africa with a few from other parts of Africa. Several Asian and Latin American species were formerly included but they have all now been transfe ...
'' (family
Apocynaceae
Apocynaceae (from ''Apocynum'', Greek for "dog-away") is a family of flowering plants that includes trees, shrubs, herbs, stem succulents, and vines, commonly known as the dogbane family, because some taxa were used as dog poison Members of the ...
)).
Notes and references
{{DEFAULTSORT:Storage Organ
Plant morphology
Energy storage
Biology terminology