Agave

Agave (/əˈɡɑːvi/, UK also /əˈɡeɪvi/, Anglo-Hispanic: /əˈɡɑːveɪ/) is a genus of monocots native to the hot and arid regions of the Americas, although some Agave species are also native to tropical areas of South America. The genus Agave (from the Ancient Greek αγαυή, agauê) is primarily known for its succulent and xerophytic species that typically form large rosettes of strong, fleshy leaves. Plants in this genus may be considered perennial, because they require several to many years to mature and flower. However, most Agave species are more accurately described as monocarpic rosettes or multiannuals, since each individual rosette flowers only once and then dies (see semelparity); a small number of Agave species are polycarpic. Along with plants from the closely related genera Yucca, Hesperoyucca, and Hesperaloe, various Agave species are popular ornamental plants in hot, dry climates, as they require very little supplemental water to survive. Most Agave species grow very slowly. Some Agave species are known by the common name 'century plant'. The succulent leaves of most Agave species have sharp marginal teeth, an extremely sharp terminal spine, and are very fibrous inside. The stout stem is usually extremely short, which may make the plant appear as though it is stemless. Agave rosettes are mostly monocarpic, though some species are polycarpic. During flowering, a tall stem or 'mast' ('quiote' in Mexico) grows apically from the center of the rosette and bears a large number of short, tubular flowers and sometimes vegetatively produced bulbils (a form of asexual reproduction). After pollination/fertilization and subsequent fruit development, in monocarpic species, the original rosette dies. However, throughout the lifetime of many Agave species, rhizomatous suckers develop above the roots at the base of the rosette. These suckers go on to form new plants after the original rosette desiccates and dies. It is important to note that not all agaves produce suckers throughout their lifetime; some Agave species rarely or never produce suckers, while others may only develop suckers after final maturation with inflorescence. Agaves can be confused with cacti, aloes, or stonecrops, but although these plants all share similar morphological adaptations to arid environments (e.g. succulence), each group belongs to a different plant family and probably experienced convergent evolution. Further, cactus (Cactaceae) and stonecrop (Crassulaceae) lineages are eudicots, while aloes (Asphodelaceae) and agaves (Asparagaceae) are monocots. Agave species are used as food plants by the larvae of some Lepidoptera (butterfly and moth) species, including Batrachedra striolata, which has been recorded on A. shawii. The agave root system, consisting of a network of shallow rhizomes, is designed to help the agave efficiently capture moisture from rain, condensation and dew. In addition to growing from seeds, most agaves produce 'pups' – young plants from runners. Agave vilmoriniana (the octopus agave) produces hundreds of pups on its bloom stalk. Agave leaves store the plant's water and are crucial to its continued existence. The coated leaf surface prevents evaporation. The leaves also have sharp, spiked edges. The spikes discourage predators from eating the plant or using it as a source of water and are so tough that ancient peoples used them for sewing needles. The sap is acidic. Some agaves bloom at a height up to 30 ft (9 m) so that they are far out of reach to animals that might attack them. Smaller species, such as Agave lechuguilla, have smaller bloom stalks. In the APG III system, the genus Agave is placed in the subfamily Agavoideae of the broadly circumscribed family Asparagaceae. Some authors prefer to place it in the segregate family Agavaceae. According to the most recent phylogenetic analyses, the genus Agave is shown to be paraphyletic with the embedded genera Manfreda, Polianthes, and Prochnyanthes. These genera are now combined with Agave to form the group described as Agave sensu lato, which contains about 252 species total. Traditionally, the genus Agave was circumscribed to be composed of about 166 species.