Agave is a genus of monocots. The plants are perennial, but each rosette flowers once and
then dies. Some species are known by the name century plant.
In the APG III system, the genus is placed in the subfamily Agavoideae of the broadly
circumscribed family Asparagaceae. Some authors prefer to place it in the segregate family
Agavaceae. Traditionally, it was circumscribed to be composed of about 166 species, but it
is now usually understood to have about 208 species.
Description Chiefly Mexican, agaves are also native to
the southern and western United States and central and tropical South America. They are
succulents with a large rosette 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, various Agave
species are popular ornamental plants.
Each rosette is monocarpic 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 short,
tubular flowers. After development of fruit, the original plant dies, but suckers are frequently
produced from the base of the stem, which become new plants.
It is a common misconception that agaves are cacti. They are not related to cacti, nor
are they closely related to Aloe whose leaves are similar in appearance.
Agave species are used as food plants by the larvae of some Lepidoptera species, including
Batrachedra striolata, which has been recorded on A. shawii.
Taxonomy In the Cronquist system and others, Agave
was placed in the family Liliaceae, but phylogenetic analyses of DNA sequences later showed it
did not belong there. In the APG II system, Agave was placed in the family Agavaceae.
When this system was superseded by the APG III system in 2009, the Agavaceae were subsumed
into the expanded family Asparagaceae, 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 this concept of Agave is now known to be paraphyletic over the genera
Manfreda, Polianthes, and Prochnyanthes. These genera are now combined with Agave as Agave
sensu lato, which contains about 208 species. In some of the older classifications, Agave
was divided into two subgenera, Agave and Littaea, based on the form of the inflorescence.
These two subgenera are probably not monophyletic. Agaves have long presented special difficulties
for taxonomy; 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, 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 tequilana, Agave attenuata, Agave parviflora, Agave murpheyi,
Agave vilmoriniana, Agave palmeri, Agave parryi and Agave victoriae-reginae.
Agave americana
One of the most familiar species is Agave americana, a native of tropical America. Common
names include century plant, maguey, or American 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 occurs in abundance in the
Karoo, 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 is used in the production of tequila. Uses
The ethnobotany of the agave was eloquently described by William H. Prescott 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 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. Each agave plant will produce several pounds
of edible flowers 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. When dried out, the stalks can be used to make
didgeridoos. 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 hemp, Agave decipiens, false sisal hemp. Agave americana is the source
of pita fiber, and is used as a fiber plant in Mexico, the West Indies and southern Europe.
During the development of the inflorescence, sap rushes to the base of the young flower
stalk. Agave nectar, a sweetener derived from the sap, is used as an alternative to sugar
in cooking, and can be added to breakfast cereals as a binding agent. The sap of A.
americana and other species is used in Mexico and Mesoamerica to produce pulque, an alcoholic
beverage. The flower shoot is cut out and the sap collected and subsequently fermented.
By distillation, a spirit called mezcal is prepared; one of the best-known forms of mezcal
is tequila. In 2001, the Mexican Government and European Union 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.
When dried and cut in slices, the flowering stem forms natural razor strops, 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
or tincture taken orally is used to treat constipation and excess gas. It is also used
as a diuretic. Root tea or tincture 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 reduce the food
vs fuel trade-off. The agave, especially Agave murpheyi, was
a major food source for the prehistoric indigenous people of the Southwestern United States.
The Hohokam of southern Arizona cultivated large areas of agave.
The Navajo similarly found many uses for the agave plant. A beverage is squeezed from the
baked fibers, and the heads can be baked or boiled, pounded into flat sheets, sun dried,
and stored for future use. The baked, dried heads are also boiled and made into an edible
paste, eaten whole, or made into soup. The leaves are eaten boiled, and the young, tender
flowering stalks and shoots are roasted and eaten as well. The fibers are used to make
rope, the leaves are used to line baking pits, and the sharp pointed leaf tips are used to
make basketry awls. Warnings
The juice from many species of agave can cause acute contact dermatitis. It will produce
reddening and blistering lasting one to two weeks. Episodes of itching may recur up to
a year thereafter, though the rash is no longer visible. Irritation is, in part, caused by
calcium oxalate raphides. 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
three weeks. Images of species and cultivars
Species See List of Agave species.
See also Agave nectar
Sisal References
Bibliography Howard Scott Gentry, Agaves of Continental
North America, the standard work, with accounts of 136 species.
Die Agaven. IPNI : The International Plant Name Index.
Native Plant Information Network More information on species in the Agave genus.
Xeric World An online community dedicated to the study of Xeric plant species with a
focus on the family Agavaceae. Kolendo, Jan. The Agave Pages. [1]
Davidson, Alan. The Oxford Companion to Food. Oxford: Oxford University press. pp. xx +
892. ISBN 0-19-211579-0.