Agave
Encyclopedia
Agave is a genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of monocots. The plants are perennial, but each rosette
Rosette (botany)
In botany, a rosette is a circular arrangement of leaves, with all the leaves at a single height.Though rosettes usually sit near the soil, their structure is an example of a modified stem.-Function:...

 flowers once and then dies (see semelparity); they are commonly known as the century plant.

In the APG III system
APG III system
The APG III system of flowering plant classification is the third version of a modern, mostly molecular-based, system of plant taxonomy...

, the genus is placed in the subfamily Agavoideae of the broadly circumscribed
Circumscription (taxonomy)
In taxonomy, circumscription is the definition of the limits of a taxonomic group of organisms. One goal of taxonomy is to achieve a stable circumscription for every taxonomic group. Achieving stability can be simple or difficult....

 family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Asparagaceae
Asparagaceae
Asparagaceae is the botanical name of a family of flowering plants, placed in the order Asparagales of the monocots.In earlier classification systems, the species involved were often treated as belonging to the family Liliaceae...

. Some authors prefer to place it in the segregate
Segregate (taxonomy)
In taxonomy, a segregate, or a segregate taxon is created when a taxon is split off, from another taxon. This other taxon will be better known, usually bigger, and will continue to exist, even after the segregate taxon has been split off...

 family Agavaceae
Agavaceae
Agavoideae is a subfamily of monocot flowering plants in the family Asparagaceae, order Asparagales. It has previously been treated as a separate family, Agavaceae. The group includes many well-known desert and dry zone types such as the agave, yucca, and Joshua tree...

. Traditionally, it was circumscribed to comprise about 166 species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

, but it is now usually understood to have about 208 species.

Description

Chiefly Mexican
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

, agaves are also native to the southern and western United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 and central and tropical South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

. They are succulents
Succulent plant
Succulent plants, also known as succulents or fat plants, are water-retaining plants adapted to arid climates or soil conditions. Succulent plants store water in their leaves, stems, and also in roots...

 with a large rosette
Rosette (botany)
In botany, a rosette is a circular arrangement of leaves, with all the leaves at a single height.Though rosettes usually sit near the soil, their structure is an example of a modified stem.-Function:...

 of thick fleshy leaves, each ending generally in a sharp point and with a spiny margin; the stout stem is usually short, the leaves apparently springing from the root. Along with plants from the related genus Yucca
Yucca
Yucca is a genus of perennial shrubs and trees in the family Asparagaceae, subfamily Agavoideae. Its 40-50 species are notable for their rosettes of evergreen, tough, sword-shaped leaves and large terminal panicles of white or whitish flowers. They are native to the hot and dry parts of North...

, various Agave species are popular ornamental plant
Ornamental plant
Ornamental plants are plants that are grown for decorative purposes in gardens and landscape design projects, as house plants, for cut flowers and specimen display...

s.

Each rosette is monocarpic
Monocarpic
Monocarpic plants are those that flower, set seeds and then die. Other terms with the same meaning are hapaxanth and semelparous. The term was first used by Alphonse de Candolle....

 and grows slowly to flower only once. During flowering, a tall stem or "mast" grows from the center of the leaf rosette and bears a large number of shortly tubular flowers. After development of fruit, the original plant dies, but sucker
Basal shoot
A basal shoot, root sprout, adventitious shoot, water sprout or sucker is a shoot or cane which grows from a bud at the base of a tree or shrub or from its roots. This shoot then becomes, or takes the form of, a singular plant. A plant that produces suckers is referred to as surculose...

s are frequently produced from the base of the stem, which become new plants.

It is a common misconception that agaves are cacti
Cactus
A cactus is a member of the plant family Cactaceae. Their distinctive appearance is a result of adaptations to conserve water in dry and/or hot environments. In most species, the stem has evolved to become photosynthetic and succulent, while the leaves have evolved into spines...

. They are not related to cacti, nor are they closely related to Aloe
Aloe
Aloe , also Aloë, is a genus containing about 500 species of flowering succulent plants. The most common and well known of these is Aloe vera, or "true aloe"....

whose leaves are similar in appearance.

Agave species are used as food plants by the larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...

e of some Lepidoptera
Lepidoptera
Lepidoptera is a large order of insects that includes moths and butterflies . It is one of the most widespread and widely recognizable insect orders in the world, encompassing moths and the three superfamilies of butterflies, skipper butterflies, and moth-butterflies...

 (butterfly
Butterfly
A butterfly is a mainly day-flying insect of the order Lepidoptera, which includes the butterflies and moths. Like other holometabolous insects, the butterfly's life cycle consists of four parts: egg, larva, pupa and adult. Most species are diurnal. Butterflies have large, often brightly coloured...

 and moth
Moth
A moth is an insect closely related to the butterfly, both being of the order Lepidoptera. Moths form the majority of this order; there are thought to be 150,000 to 250,000 different species of moth , with thousands of species yet to be described...

) species including Batrachedra striolata
Batrachedra
Batrachedra is the largest genus in the moth family Batrachedridae.It includes the following species:*Batrachedra acrodeta*Batrachedra agaura*Batrachedra albanica*Batrachedra albicapitella*Batrachedra albistrigella...

, which has been recorded on A shawii.

Taxonomy

In the Cronquist system
Cronquist system
The Cronquist system is a taxonomic classification system of flowering plants. It was developed by Arthur Cronquist in his texts An Integrated System of Classification of Flowering Plants and The Evolution and Classification of Flowering Plants .Cronquist's system places flowering plants into two...

 and others, Agave was placed in the family Liliaceae
Liliaceae
The Liliaceae, or the lily family, is a family of monocotyledons in the order Liliales. Plants in this family have linear leaves, mostly with parallel veins but with several having net venation , and flower arranged in threes. Several have bulbs, while others have rhizomes...

, but phylogenetic analyses of DNA sequence
DNA sequence
The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...

s later showed that it did not belong there. In the APG II system
APG II system
The APG II system of plant classification is the second, now obsolete, version of a modern, mostly molecular-based, system of plant taxonomy that was published in April 2003 by the Angiosperm Phylogeny Group. It was a revision of the first APG system, published in 1998, and was superseded in 2009...

, Agave was placed in the family Agavaceae. When this system was superseded by the APG III system
APG III system
The APG III system of flowering plant classification is the third version of a modern, mostly molecular-based, system of plant taxonomy...

 in 2009, Agavaceae was subsumed into the expanded family Asparagaceae
Asparagaceae
Asparagaceae is the botanical name of a family of flowering plants, placed in the order Asparagales of the monocots.In earlier classification systems, the species involved were often treated as belonging to the family Liliaceae...

, and Agave was treated as one of 18 genera in the subfamily Agavoideae.

Agave had long been treated as a genus of about 166 species, but it is now known that this concept of Agave is paraphyletic over the genera Manfreda
Manfreda
Manfreda is a genus of about 20 species of flowering plants in the family Asparagaceae, subfamily Agavoideae. Along with Polianthes, members are commonly called tuberoses. Some authorities place Manfreda in genus Polianthes, while others group place both genera in Agave...

, Polianthes
Polianthes
Polianthes is a genus of plants in family Asparagaceae, subfamily Agavoideae. It includes tuberose , a plant that is commonly used in perfume making...

, and Prochnyanthes. These genera are now combined with Agave as Agave sensu lato, which contains about 208 species. In some of the older classifications
Biological classification
Biological classification, or scientific classification in biology, is a method to group and categorize organisms by biological type, such as genus or species. Biological classification is part of scientific taxonomy....

, Agave was divided into two subgenera, Agave and Littaea, based on the form of the inflorescence
Inflorescence
An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...

. These two subgenera are probably not monophyletic.

Agaves have long presented special difficulties for taxonomy
Alpha taxonomy
Alpha taxonomy is the discipline concerned with finding, describing and naming species of living or fossil organisms. This field is supported by institutions holding collections of these organisms, with relevant data, carefully curated: such institutes include natural history museums, herbaria and...

; variations within a species may be considerable, and a number of named species are of unknown origin and may just be variants of original wild species.

Spanish and Portuguese explorers probably brought agave plants back to Europe with them, but the plants became popular in Europe during the 19th century, when many types were imported by collectors. Some have been continuously propagated by offset since then, and do not consistently resemble any species known in the wild, although this may simply be due to the differences in growing conditions in Europe.

Commonly grown species

The most commonly grown species include Agave americana, Agave angustifolia
Agave angustifolia
Agave angustifolia is a plant which is native to Mexico and Central America. It is used to make mezcal and also as an ornamental plant, particularly the cultivar 'Marginata'....

, Agave tequilana, and Agave attenuata
Agave attenuata
Agave attenuata is a species of agave sometimes known as the "lion's tail", "swan's neck", or "foxtail" for its development of a curved stem, unusual among agaves...

.

Agave americana

One of the most familiar species is Agave americana, a native of tropical America. Common names include century plant, maguey (in Mexico), or American aloe (it is not, however, closely related to the genus Aloe
Aloe
Aloe , also Aloë, is a genus containing about 500 species of flowering succulent plants. The most common and well known of these is Aloe vera, or "true aloe"....

). The name "century plant" refers to the long time the plant takes to flower. The number of years before flowering occurs depends on the vigor of the individual plant, the richness of the soil and the climate; during these years the plant is storing in its fleshy leaves the nourishment required for the effort of flowering.

Agave americana, century plant, was introduced into Europe about the middle of the 16th century, and is now widely cultivated as an ornamental; in the variegated forms, the leaf has a white or yellow marginal or central stripe. As the leaves unfold from the center of the rosette, the impression of the marginal spines is conspicuous on the still erect younger leaves. The plants require protection from frost. They mature very slowly and die after flowering, but are easily propagated by the offsets from the base of the stem.

Blue A. americana occur in abundance in the Karoo
Karoo
The Karoo is a semi-desert region of South Africa. It has two main sub-regions - the Great Karoo in the north and the Little Karoo in the south. The 'High' Karoo is one of the distinct physiographic provinces of the larger South African Platform division.-Great Karoo:The Great Karoo has an area of...

, and arid highland regions of South Africa. Introduced by the British settlers in 1820, the plant was originally cultivated and used as emergency feed for livestock. Today it is used mainly for the production of syrup and sugar.

Agave attenuata

A. attenuata is a native of central Mexico and is uncommon in its natural habitat. Unlike most species of Agave, A. attenuata has a curved flower spike from which it derives one of its numerous common names - the foxtail agave. A. attenuata is also commonly grown as a garden plant. Unlike many agaves, A. attenuata has no teeth or terminal spines, making it an ideal plant for areas adjacent to footpaths. Like all agaves, A. attenuata is a succulent and requires little water or maintenance once established.

Agave tequilana

Agave azul (blue agave) is used in the production of tequila
Tequila
Tequila is a spirit made from the blue agave plant, primarily in the area surrounding the city of Tequila, northwest of Guadalajara, and in the highlands of the western Mexican state of Jalisco....

.

Uses

The ethnobotany
Ethnobotany
Ethnobotany is the scientific study of the relationships that exist between people and plants....

 of the agave was eloquently described by William H. Prescott
William H. Prescott
William Hickling Prescott was an American historian and Hispanist, who is widely recognized by historiographers to have been the first American scientific historian...

 in 1843:

But the miracle of nature was the great Mexican aloe, or maguey, whose clustering pyramids of flowers, towering above their dark coronals of leaves, were seen sprinkled over many a broad acre of the table-land. As we have already noticed its bruised leaves afforded a paste from which paper was manufactured, its juice was fermented into an intoxicating beverage, pulque, of which to the natives, to this day, are extremely fond; its leaves further supplied an impenetrable thatch for the more humble dwellings; thread, of which coarse stuffs were made, and strong cords, were drawn from its tough and twisted fibers; pins and needles were made from the thorns at the extremity of its leaves; and the root, when properly cooked, was converted into a palatable and nutritious food. The agave, in short, was meat, drink, clothing, and writing materials for the Aztec! Surely, never did Nature enclose in so compact a form so many of the elements of human comfort and civilization!

There are four major parts of the agave that are edible: the flowers, the leaves, the stalks or basal rosettes, and the sap (called aguamiel—honey water). (Davidson 1999)

Each agave plant will produce several pounds of edible flowers
Edible flowers
Edible flowers are flowers that can be consumed safely. Edible flowers may be preserved for future use using techniques such as drying, freezing or steeping in oil. They can be used in drinks, jellies, salads, soups, syrups and main dishes. Flower-flavoured oils and vinegars are made by steeping...

 during its final season. The stalks, which are ready during the summer, before the blossom, weigh several pounds each. Roasted, they are sweet and can be chewed to extract the aguamiel, like sugarcane
Sugarcane
Sugarcane refers to any of six to 37 species of tall perennial grasses of the genus Saccharum . Native to the warm temperate to tropical regions of South Asia, they have stout, jointed, fibrous stalks that are rich in sugar, and measure two to six metres tall...

. When dried out, the stalks can be used to make didgeridoo
Didgeridoo
The didgeridoo is a wind instrument developed by Indigenous Australians of northern Australia around 1,500 years ago and still in widespread usage today both in Australia and around the world. It is sometimes described as a natural wooden trumpet or "drone pipe"...

s. The leaves may be collected in winter and spring, when the plants are rich in sap, for eating. The leaves of several species also yield fiber: for instance, Agave rigida var. sisalana, sisal
Sisal
Sisal is an agave that yields a stiff fibre traditionally used in making twine, rope and also dartboards. The term may refer either to the plant or the fibre, depending on context...

 hemp, Agave decipiens, false sisal hemp. Agave americana is the source of pita fiber, and is used as a fiber plant in Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

, the West Indies and southern Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

.

During the development of the inflorescence
Inflorescence
An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...

, there is a rush of sap to the base of the young flower stalk. Agave nectar (also called agave syrup), a sweetener derived from the sap, is used as an alternative to sugar
Sugar
Sugar is a class of edible crystalline carbohydrates, mainly sucrose, lactose, and fructose, characterized by a sweet flavor.Sucrose in its refined form primarily comes from sugar cane and sugar beet...

 in cooking and it can be added to breakfast cereal
Breakfast cereal
A breakfast cereal is a food made from processed grains that is often, but not always, eaten with the first meal of the day. It is often eaten cold, usually mixed with milk , water, or yogurt, and sometimes fruit but sometimes eaten dry. Some cereals, such as oatmeal, may be served hot as porridge...

s as a binding agent. In the case of A. americana and other species, this is used in Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

 and Mesoamerica
Mesoamerica
Mesoamerica is a region and culture area in the Americas, extending approximately from central Mexico to Belize, Guatemala, El Salvador, Honduras, Nicaragua, and Costa Rica, within which a number of pre-Columbian societies flourished before the Spanish colonization of the Americas in the 15th and...

 in the production of the beverage pulque
Pulque
Pulque, or octli, is a milk-colored, somewhat viscous alcoholic beverage made from the fermented sap of the maguey plant, and is a traditional native beverage of Mexico. The drink’s history extends far back into the Mesoamerican period, when it was considered sacred, and its use was limited to...

. The flower shoot is cut out and the sap collected and subsequently fermented. By distillation, a spirit called mezcal
Mezcal
Mezcal, or mescal, is a distilled alcoholic beverage made from the maguey plant native to Mexico. The word mezcal comes from Nahuatl metl and ixcalli which mean 'oven cooked agave.'...

 is prepared; one of the best-known forms of mezcal is tequila
Tequila
Tequila is a spirit made from the blue agave plant, primarily in the area surrounding the city of Tequila, northwest of Guadalajara, and in the highlands of the western Mexican state of Jalisco....

. In 2001, the Mexican Government and European Union
European Union
The European Union is an economic and political union of 27 independent member states which are located primarily in Europe. The EU traces its origins from the European Coal and Steel Community and the European Economic Community , formed by six countries in 1958...

 agreed upon the classification of tequila and its categories. All 100% blue agave tequila must be made from the Weber blue agave plant, to rigorous specifications and only in certain Mexican states.

People have found a few other uses of the plant aside from its several uses as food. When dried and cut in slices, the flowering stem forms natural razor strop
Razor strop
A razor strop is a flexible strip of leather or canvas used to straighten and polish the blade of a straight razor, a knife, or a woodworking tool like a chisel...

s, and the expressed juice of the leaves will lather in water like soap. The natives of Mexico used the agave to make pens, nails and needles, as well as string to sew and make weavings. Leaf tea
Tea
Tea is an aromatic beverage prepared by adding cured leaves of the Camellia sinensis plant to hot water. The term also refers to the plant itself. After water, tea is the most widely consumed beverage in the world...

 or tincture
Tincture
A tincture is an alcoholic extract or solution of a non-volatile substance . To qualify as a tincture, the alcoholic extract is to have an ethanol percentage of at least 40-60%...

 taken orally is used to treat constipation
Constipation
Constipation refers to bowel movements that are infrequent or hard to pass. Constipation is a common cause of painful defecation...

 and excess gas. It is also used as a diuretic
Diuretic
A diuretic provides a means of forced diuresis which elevates the rate of urination. There are several categories of diuretics. All diuretics increase the excretion of water from bodies, although each class does so in a distinct way.- Medical uses :...

. Root tea or tincture
Tincture
A tincture is an alcoholic extract or solution of a non-volatile substance . To qualify as a tincture, the alcoholic extract is to have an ethanol percentage of at least 40-60%...

 is taken orally to treat arthritic joints. Several agave species are also considered to have potential as effective bioenergy crops. Agave's ability to grow in naturally water-limited environments could help to prevent the food vs fuel
Food vs fuel
Food vs. fuel is the dilemma regarding the risk of diverting farmland or crops for biofuels production in detriment of the food supply on a global scale. The "food vs. fuel" or "food or fuel" debate is international in scope, with good and valid arguments on all sides of this issue...

 trade-off.

Warnings

The juice from many species of agave can cause acute contact dermatitis
Dermatitis
-Etymology:Dermatitis derives from Greek derma "skin" + -itis "inflammation" and genetic disorder.-Terminology:There are several different types of dermatitis. The different kinds usually have in common an allergic reaction to specific allergens. The term may describe eczema, which is also called...

. It will produce reddening and blistering lasting one to two weeks. Episodes of itching may recur up to a year thereafter, even though there is no longer a visible rash. Irritation is, in part, caused by calcium oxalate
Calcium oxalate
Calcium oxalate is a chemical compound that forms needle-shaped crystals, known in plants as raphides. A major constituent of human kidney stones, the chemical is also found in beerstone, a scale that forms on containers used in breweries...

 raphides
Raphides
Raphides are needle-shaped crystals of calcium oxalate as the monohydrate or calcium carbonate as aragonite, found in more than 200 families of plants.Both ends are needle-like, but raphides tend to be more blunt at one end and more tapering at the other....

. Dried parts of the plants can be handled with bare hands with little or no effect. If the skin is pierced deeply enough by the needle-like ends of the leaf from a vigorously growing plant, this can also cause blood vessels in the surrounding area to erupt and an area some 6–7 cm across appear to be bruised. This may last up to two to three weeks.
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