– PLANT DESCRIPTION:
The largest and most majestic of the native Texas Agaves, Agave americana often grows as tall as 6 feet. Its leaves are gray-blue to blue-green with spines at the tips and on the margins; the older leaves often gracefully arch down. Century plant lives for 10 to 25 years (the “century” is an exaggeration) before it uses all its reserves to produce a magnificent flower stalk that can be 15 feet tall. After that the original plant dies, but is replaced by small offshoots around the base. In Texas it grows in dry, gravelly soils in the south, but is naturalized and grown farther north and west. Like most Agaves, A. americana needs full sun and well drained soil to thrive. It is extremely drought tolerant and moderately slow-growing. Supplemental water in dry summer months will make it grow faster, but care must be taken not to over-water, especially in clay soils, because too much moisture will cause the roots to rot. It is hardy to about 20 degrees F., and like most Agaves, is tolerant of reflected heat. Several variegated forms of Agave americana are in cultivation. (1)
Some agave flower stalks are covered with hundreds of bulbils, sometimes called plantlets (pictured right). Growing from a bud at the base of each flower, a bulbil is a miniature clone of the parent plant. The longer it stays attached, the larger it grows.
Eventually, bulbils fall to the ground and may take root. Rather than wait for nature to take its course, gardeners can remove bulbils from the stalk as soon as they can be easily pulled off, without resistance or tissue damage. Keep in mind that the bottom of a bulbil must be intact for roots to develop. (2)
Types of Agave:
There are many other types of agave, which makes it easy to find and garden with this stunning plant. Some of these include:
- Agave parryi
- Agave ocahui
- Agave macroacantha
- Agave gigantensis
Agave have a large tap root and do not transplant well, so choose an appropriate site when planting agave. The majority of the roots are surface roots and do not require a deep hole if planted when young. Check your soil for drainage, or if planting in heavy clay soils amend the soil with sand or grit. Mix in enough sand to make the soil halfway comprised of grit. Water the plant diligently for the first week and then cut it to half the second week. Taper off even more until you are only watering once every week or two.
Growing agave is easy if you plant the right variety in the right location. Agaves need full sun and gritty soil that percolates easily. They can even do quite well when potted but use an unglazed clay pot that will allow evaporation of excess moisture.
Water needs are moderate to light depending upon the heat of the season but the plants should be allowed to dry out before irrigation.
In spring they benefit from the application of a granulated time release fertilizer that will provide nutrient needs for the season.
Many varieties of agave will die after blooming and then produce pups or offshoots from their base to replace themselves. On varieties where the parent plant doesn’t die after flowering, it is a good idea to get long handled pruners and remove the spent bloom.
After establishment, neglect is actually how to grow agave and produce happy plants.
– CHEMICAL COMPOSITION:
– Study isolated two new spirostanol glycosides: agamenoside A and B.
– Study yielded a new steroidal saponin: a bisdesmosidic spirostanol saponin.
– Studies on chemical composition of leaves yielded high amount of total dietary fiber (38.40%), total sugars (45.83%), and protein (35.33%), with a relatively low ash content (5.94%) and lipid (2.03%). Agave inulin showed significant differences when compared to commercial inulin.
– Study of leaves isolated tigogenin, hecogenin, 9-dehydrohecogenin, rockogenin,12-epirockogenin, gitogenin, chlorogenin and manogenin.
– AGAVE USES & BENEFITS:
- Considered antiseptic, depurative, diuretic and laxative.
- Studies suggest antibacterial, anti-inflammatory properties
- The pineapple-shaped heart of the plant yields a sweet sticky juice, agave nectar, which can be made into a syrup and used as a sweetener, with a taste similar to honey.
- Agave is best known for its role in tequila.
- Antibacterial: Study yielded tetratriacontanol, tetratriacontyl hexadecanoate and a new 2-tritriacontylchromone; two of them exhibited significant antibacterial activity. (5)
- Anti-Inflammatory: Study evaluated the anti-inflammatory activity of aqueous extracts and steroidal sapogenins of Agave americana. Extracts showed good anti-inflammatory activity. (6)
- Hecogenin Tetraglycoside /Cytotoxic activity: A new steroidal saponin from the leaves of Agave americana: Study isolated a new bisdesmosidic spirostanol saponin along with three known saponins. Hecogenin tetraglycoside showed cytotoxic activity against HL-60 human promyelocytic leukemia cells.
- Cytotoxic activity: Study evaluated the cytotoxicity of various parts of medicinal plants such as Agave americana, Strychnos nuxvomica and Areca catechu using MCF-7 and Vero cell line. Results showed the methanol extract of Agave americana and aqueous extract of Areca catechu are potent cytotoxic. (7)
- Anti-Anxiety / Leaves: Study evaluated the anti-anxiety effects of an ethanolic extract of Agave americana leaves in rat and mice. Results obtained from experimental models confirmed the anxiolytic activity (400mg/kg) comparable to standard drug diazepam. Activity was attributed to flavonoid phytoconstituents. (8)
- Anti-Leishmanial / Leaves: Study evaluated the comparative in vitro anti-leishmanial activity of various fractions of Agave americana extracts. An ethyl acetate fractions showed significant anti-leishmanial activity with IC50-25 µg/ml complete inhibition (IC50) at 50µg/ml. (9)
- Agave Dermatitis: Study reports on a case of Agave-induced purpura in an otherwise healthy patient. Histopathology was consistent with an evolving leukocytoclastic vasculitis. (10) Study reports on 12 cases of self-inflicted contact dermatitis provoked by Agave americana, ten with systemic signs and symptoms, 8 with abnormal laboratory results. Treatment consisted of oral antihistamines and topical saline compresses. (11)
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