Herbs in History: Aloe

Aloe Aloe vera CONTENTS Socotra? A Recent Introduction The Making of a Tradition Back to the East References

By Alain Touwaide & Emanuela Appetiti | October 2022

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Socotra?

In his Qanun (Canon), the omniscient ibn Sina (980-1037) best known in the Western World as Avicenna, identified aloe as a plant from the island of Socotra, that is, the Socotra Archipelago, east of the Horn of Africa, now Socotra Governorate of Yemen. Ever since, aloe has been considered as a plant from Socotra, with the best and most used species (Aloe perryi Bak.) coming indeed from the island. The story is much longer, however.
 

A Recent Introduction

Illustration 1: Aloe barbadensis

Typical of the tropical climates, aloes grow in dry soils, including poor ones, with abundant exposure to the sun and warm temperatures. It is propagated from seeds and offsets that grow roots.
 
Native to southern Africa, where it is represented by the species Aloe arborescens Mill. and A. ferox Mill. (currently known as Cape Aloe), the genus Aloe (in the family of the Asphodelaceae) had an extraordinary history of diffusion reaching West Africa, the Saharan-Sudanian region, and the Arabian Peninsula via the Ethiopian-Somalian world, also arriving on Madagascar from the Zambezian area, with repeated processes of introduction in the Arabian Peninsula and Madagascar. Along these roads, the genus went through different events of speciation. The most important species in history and in present times is Aloe barbadensis Miller (mostly known as Aloe vera (L.) Burm. f.), native to the Arabian Peninsula (Illustration 1). And, early in history, this species was acclimated to India.
 
Whereas different species of aloe are now established in the Mediterranean region, particularly in coastal areas, they arrived recently in the region. No species appear, indeed, in the vast collection of medical treatises attributed to Hippocrates (5^th-4^th cent. BCE), the Father of Medicine, even though several genera of plants non-native of the Mediterranean region are attested in the so-called Hippocratic collection. Similarly, no aloe is included in the founding treatises of botany of the Ancient World, the works by Theophrastus (4^th-3^rd century BCE), which do refer to plants discovered by the troops of Alexander the Great (356-323) in their odyssey from Macedonia (central Greece) to Northern India. Educated by the scientist and philosopher Aristotle (384-322 BCE), Alexander invited scientists to accompany his troops to record and report all the discoveries he was expecting to make, from people and skies to plants and other natural curiosities. Data from these reports were included by Theophrastus in his two treatises Historia Plantarum (Inquiry on Plants) and De causis plantarum (Physiology of Plants). No aloe appears in either work.
 
The first written trace of aloe in the medical and scientific literature of the Mediterranean World appears in the encyclopedia of materia medica by the Greek Dioscorides (1^st cent. CE). There we find a precise description of the plant that allows for identification (Illustration 2):
 

Illustration 2: Close-up view of thorny aloe leaf

Aloe. It has a leaf quite similar to that of squill, bright, large, thick …, curling backward. On each of their edges, the leaves have thorns slightly protruding, truncated. It produces a stem like that of the asphodel, a white flower and a fruit similar to that of asphodel … It is single-rooted, having a root like a spike …
 

Most interesting for our purpose here, is the distribution of aloe according to Dioscorides:
 

It is abundant in India, where comes the sap (exported for use); it also grows in Arabia and Asia, in some coastal areas and islands, as, for example, Andros.
 

This supposed distribution is particularly significant, because it reveals that the ancient Greek world traded the drug made of aloe sap from India even though it knew that the plant grows in other places that are not well identified here, except Arabia. Even more significant the reference to the island of Andros, close to the region of Athens (Attic) and the large island of Euboea, hinting at a diffusion of the species from east to west throughout the Mediterranean World.
 
The rather exact description of the plant goes together with a fine environmental note, that is, the presence of aloe in coastal regions, which is still the case.
 
This description has been traditionally used to affirm that aloe was introduced in Mediterranean medicine at the latest in the 1^st century CE, that is, at Dioscorides’ tine. However sure it might seem, this statement is far from certain.
 
Dioscorides’ De materia medica is a vas compilation in which each materia medica is dealt with in a chapter. The chapters resulting from the collection of material are assembled in a very clear structure, with two levels of grouping: first, the plants with similar botanical structures, organoleptic qualities or medical properties are grouped in coherent units sometimes corresponding to present-day taxonomy (e.g. the Solanaceae); then, all the groups created in that way, are ordered in a significant way defined by the therapeutic properties of these groups, from warming to cooling, on a scale of gradual reduction of the former and increase, instead, of the latter.
 
Returning to aloe, its chapter in De materia medica appears alone, between two groups to which it is unrelated: thistles before, and aromatic plants after. In addition, all the plants coming from the East, including India, are presented at the beginning of the work, forming the group of the plants coming from warm climates that were known to the Greeks

 All this suggests that the chapter on aloe might not be part of the original version of De materia medica, but might be an addition, introduced at some point in time in the transmission of the treatise by a user of De materia medica who annotated a copy of the text. This might have happened in the form of a fly leaf, as a personal note, which was inserted in the treatise at a random place. Further on, this additional note was integrated into the text as if it were a chapter of the original form of De materia medica, resulting in the out-of-order presence of aloe in Dioscorides’ compilation. Assuming that this is correct, we do not know when and where the author of the entry on aloe introduced it into Dioscorides’ work.

 

The Making of a Tradition

Whoever the author of this chapter was and whenever he was active, he listed the therapeutic applications of aloe sap, with both internal and external uses (though more of the latter than of the former). Generally, aloe was considered astringent, desiccative, and soporific. Internally, it is a purgative, stops blood-spitting (tuberculosis? Or infections of the digestive tract?), treats jaundice, and all conditions of the mouth (including tonsilitis).  In external use (applied dry, or diluted in wine or honey), it treats all kinds of injuries (including in affections of the eyes such as blepharitis), which it helps to cicatrize. It also stops hair loss. Applied on the head, specifically on the temples, with vinegar and rose unguent, it was said to relieve headache. The juice was adulterated by mixing it with gum.
 
In the 2^nd/3^rd century CE, Galen also devoted a chapter to aloe in his vast encyclopedia of therapeutic substances. He did not follow Dioscorides as he often did, even though he presented similar information. For him aloe comes from India (which produced the best species according to him) and Syria (that is, the Near East and not Syria strictly speaking). It is astringent and desiccative as in Dioscorides, in addition to bitter, which does not appear in Dioscorides, instead. For Galen, aloe is mostly warming, with a mild intensity, identified at the 1^st or 2^nd degree on a scale of 4 such degrees. Galen recommended it for a range of medical conditions that is quite different from that in Dioscorides: as a cathartic, for the stomach, to close and clean wounds, particularly in the anus (hemorrhoids) and the genitals, and to reduce inflammation in the mouth, nose, and eyes.
 
After the Greek scientific and medical literature was translated into Arabic from the late-8^th century on, scientists in the Arabic Empire compiled new syntheses similar to those by Dioscorides and Galen. One of them, possibly the most analytical, was the Qanun (Canon) by Avicenna.
 
Whereas his Greek predecessors valued more the Indian aloe, Avicenna recommended the aloe from Socotra, considering that the species from Egypt are of lower quality. For him, the plant is warming at the 3^rd degree, that is, much at much higher degree than according to Galen, and it is astringent, desiccative, and soporific. On this basis, it is very useful, including in cosmetology, as it cleans wounds and spots on the skin. As the presence of the soporific action indicates, Avicenna mostly reproduced all the uses attested in Dioscorides, which he developed further.
 
With the transmission of Arabic science and medicine to the West through translations into Latin, aloe was introduced to the Middle Ages. In the 13^th-century Tractatus de herbis (Treatise on Medicinal Plants) it is analyzed in a long chapter that summarizes, and expands on, previous knowledge, attesting to the making of a tradition through the amalgamation of all earlier knowledge and new data.
 
In this chapter, aloe is said to grow not only in India, Persia, and Greece, but also in Apulia, that is, Southern Italy, where it probably was introduced by the Arabs in a further expansion westward. Of the various species, the Treatise recommended the Socotra variety as per Avicenna’s statement.
 
Regarding aloe’s general therapeutic property, it is considered warming at the 2^nd degree as in Avicenna’s Canon, being also desiccative as in Dioscorides, at the same degree (2^nd) by an extension of Galen’s system of measurement of therapeutic actions to this property.
 
The uses are an assemblage of data from De materia medica and Galen, with one from Avicenna and some new ones. In internal use aloe is cathartic as in Galen, and it relieves a heavy stomach, as well as the spleen and the liver. It also cleans wounds in the genitals and stops bleeding from wounds, also from Galen. In external use, it relieves headache as De materia medica already stated. As a cosmetic, it gives a good color to the skin and it stops hair loss as in Avicenna’s Canon.
 
As for other indications, the use in gynecology to provoke menses, is new. The others, instead, might result from an extension of previous uses, possibly thanks to new trials, with applications in ophthalmology, to clarify vision, in oto-rhino-laryngology, to reduce swellings of the ears.

 

Illustration 3: Remberti Dodonaei, Stirpium Historiae Pemptdes Sex, sive Libri XXX. Antverpiae: Ex Officina Christophori Plantini, 1583, p. 355. Aloë ex America

With the Fall of Constantinople in 1453 and the diffusion of the printing press, ancient information was more common and more largely disseminated in the West. In his epoch-making Historia Stirpium (Inquiry into Medicinal Plants), the German herbalist and physician Leonhart Fuchs (1501-1566) literally translated the chapters of Dioscorides and Galen to which he added elements taken from the natural history encyclopedia by Pliny (1^st cent. CE). Interestingly, in his measurement of the degree of action of the major properties of aloe, he combined data from Dioscorides, Galen, and Avicenna: if he considered that aloe is warming at the 1^st or 2^nd degree in a way that recalls Galen, he added that it is desiccative at the 3^rd, transferring the degree of intensity of the warming property as per Avicenna to an action mentioned in De materia medica without any measurement of intensity.
 
The subsequent history followed the earlier pattern, with the Flemish Rembert Dodoens following Dioscorides in his Kruijdeboeck (Book on Herbs) published in 1554. However, he expanded the distribution of aloe, listing not only Southern Italy as the Tractatus already did, but also Spain, mentioning however that this Spanish species was not of any use. More than anything, Dodoens reported a species growing in “America”, with larger and stronger, spiny leaves. And he included a representation of this species in his work (Illustration 3). For the medicinal uses of the plant, he repeated the properties of earlier literature (warming and desiccative), and reproduced ancient indications, referring to Dioscorides specifically for the use in ophthalmology.  
 

Back to the East

It is a scholarly tradition to consider that aloe is mentioned in the Bible. However, in almost all mentions, the plant appears in conjunction with fragrant species, myrrh, and frankincense, cassia and cinnamon, and also spikenard, saffron, and calamus. This is also the case in the passage of the Gospels, where Apostle John reported that Nicodemus brough “a mixture of myrrh and aloes” to be used for Jesus’ burial. Although the chronology of the latter reference might be compatible with the recent introduction of aloe in the Mediterranean (possibly 1^st cent. CE), the repeated mention of fragrance does not favor such an identification. The substance referred to here is in fact the resinous wood of Aquilaria malacensis Lam. (A. agallocha Roxb., Thymeleaeceae), a large tree of the Malayan Peninsula, the wood of which was indeed used as a drug in the past. Agarwood does appear in Dioscorides, De materia medica, in the group of the exotic plants at the beginning of the treatise, where it is identified as a scented wood coming from India and Arabia.
 
If aloe was not present in the Bible, it was instead at Socotra later, where it even became a monopoly of the Sultan as the reports from the East Indian Company confirm much later.

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