Aloe and agave (Agave serrata) both belong to the Asparagales order and are characterized by their drought resistance, succulent and thick leaves, and thorns along the leaf margins. As succulents, they are frequently seen being cultivated in urban areas in Japan. However, many people mistakenly identify agave as aloe. Agave is clearly taller and has wider leaves, so it should be easy to distinguish them if you know what to look for. Not only that, but their flower shapes and ecology are completely different, and their uses are also contrasting. This article will explain the classification, morphology, and ecology of the Aloe and Agave genera.
What is Aloe or Agave?
Aloe is a general term for plants belonging to the genus Aloe in the family Hemerocallisaceae, order Asparagales, and includes species such as Aloe arborescens and Aloe vera.
Agave is a general term for plants belonging to the genus Agave in the family Asparagaceae (formerly known as the order Asparagales), and includes species such as Agave americana 'Marginata', Agave americana, Agave stricta, and Agave victoriae-reginae.
All of these plants belong to the Asparagales order and are characterized by their drought tolerance, succulent and thick leaves, and thorns along the leaf margins. As a type of succulent plant, they are an introduced species, but can be frequently seen in urban areas in Japan.
Aloe belongs to the forget-me-not family, while agave belongs to the Asparagaceae family (also known as the Asparagaceae family), so they are completely different in terms of classification.
Furthermore, aloe is native to the African continent, while agave is native to the Americas, so their evolutionary histories are completely different.
However, perhaps because agave is not very well known, when people see an agave while walking around Japan, they often mistake it for an aloe.
What are some of the Aloe and Agave species commonly seen by the roadside?
As mentioned above, it's best to think of aloe and agave as general terms, but the types of aloe and agave plants you see on the roadsides in Japan are limited.
The most commonly seen species of Aloe found on roadsides in Japan is Aloe arborescens, also known as tree aloe.
Aloe arborescens, also known as tree aloe, is sometimes simply called aloe. The name "rokai" may sound unfamiliar, but it is written with the kanji characters "蘆薈" and is an old name for aloe. Please note that the "aloe" that you usually eat, such as in aloe yogurt, is a different species called Aloe vera (Barbados aloe), so do not confuse them. This is another point that can be confusing.
Aloe arborescens is a perennial herb or shrub native to South Africa (South Africa to Mozambique) and is cultivated worldwide for ornamental purposes. In Japan, it has escaped cultivation and become naturalized (wild) along the Pacific coast, including Kyushu, the Seto Inland Sea, the Izu Peninsula, and the Boso Peninsula.
On the other hand, the most commonly seen Agave species along roadsides in Japan are Agave americana 'Marginata' and Agave americana.
Agave americana 'Marginata' is an evergreen perennial cultivar of Agave americana, which is native to Mexico and Texas in the United States and is cultivated as an ornamental plant all over the world, including Japan.
Of course, this does not apply to botanical gardens and similar places.
For information on the differences between Agave and Agave americana, please see our separate article.
Therefore, it is mainly necessary to distinguish between two types: Aloe arborescens and Agave.
What is the difference between Aloe arborescens and Agave?
Let's begin by considering the morphological differences between Aloe arborescens and Agave.
First, their overall size is completely different. While Aloe arborescens naturally grows to a height of 2-3 meters, in Japan, due to the different environment, it often remains at 30-100 cm, whereas Agave can grow to a considerably larger size of 1-2 meters.
Therefore, it grows to be as tall as a person, so even just looking at this, you can immediately tell that it is an agave plant.
Regarding the leaves, Aloe arborescens has many long, narrow leaves, while Agave has broad leaves and a limited number of leaves.
Regarding flowers, there is a crucial difference: Aloe arborescens produces cylindrical flowers similar in shape to lilies every year, about 4 cm long and ranging in color from red to dark orange, while agave flowers only once every few decades, and each plant produces only one upward-facing flower, with the flower consisting only of short green perianth segments (where the distinction between petals and sepals is unclear).
This reflects differences in pollination ecology, that is, the types of animals that visit the flowers in their native habitat.
In Aloe arborescens, the flowers are diurnal and bird-pollinated, with slender, red flowers that have evolved to attract birds with long tongues or beaks that prefer the color red (Hargreaves et al., 2012).
On the other hand, agave plants are primarily pollinated by nocturnal bats, and have evolved to provide nectar and pollen to bats at night, which then carry the pollen to other individuals (Trejo-Salazar et al., 2016; Eguiarte et al., 2021). Therefore, they lack prominent perianth segments, an adaptation for bats, which do not use their vision at night.
For more details on this aspect of agave, please see our separate article.
What are the differences in how to use Aloe arborescens and Agave?
There are also differences in how they are used.
Aloe arborescens is famous as a plant with medicinal properties, so much so that it is commonly called "the plant that makes doctors unnecessary." Historically, it has been used as a stomach tonic and laxative, by eating the transparent, fleshy part of the fresh leaves, drinking the dried leaves as aloe tea, and applying the juice of the fresh leaves externally to treat athlete's foot and burns (Kawahara, 2015).
On the other hand, agave plants store a nectar called agua miel (agave syrup) inside their bodies, and are used as raw materials for pulque (fermented agave liquor) and mezcal (a Mexican distilled spirit made primarily from agave). Tequila is a type of mezcal, but it refers to tequila made from the closely related species Agave tequilana (blue agave), and cannot be made from the agave plants commonly found in towns (Kuramitsu, 2021).
References
Eguiarte, LE, Jiménez Barrón, OA, Aguirre-Planter, E., Scheinvar, E., Gamez, N., Gasca-Pineda, J., … & Souza, V. (2021). Evolutionary ecology of Agave: distribution patterns, phylogeny, and coevolution (an homage to Howard S. Gentry). American Journal of Botany, 108 (2), 216-235. https://doi.org/10.1002/ajb2.1609
Hargreaves, AL, Harder, LD, & Johnson, SD (2012). Floral traits mediate the vulnerability of aloes to pollen theft and inefficient pollination by bees. Annals of Botany, 109 (4), 761-772. https://doi.org/10.1093/aob/mcr324
Kawahara, Katsuyuki. (2015). Edible wild plants and medicinal plants. Nanpo Shinsha. ISBN: 9784861243271
Kuramitsu, Jun. (2021). Authentic Shochu as seen from the export strategies of tequila and mezcal. Journal of the Brewing Society of Japan, 116 (2), 77-88. ISSN: 0914-7314, https://agriknowledge.affrc.go.jp/RN/2030937155
Trejo-Salazar, RE, Eguiarte, LE, Suro-Piñera, D., & Medellin, RA (2016). Save our bats, save our tequila: industry and science join forces to help bats and agaves. Natural Areas Journal, 36 (4), 523-530. https://doi.org/10.3375/043.036.0417
