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[“Manna Lichen”; syn. Lecanora esculenta]
FOLK NAMES: Torba (Libyan shepherds: Libya); Trub (Bedouin sheep herders: Libya)
USES: Food (northern Africa and west central Asia), Animal Feed (Libya), Alcoholic Beverages (Arabic), Medicine (Arabic, Cyrenaica)
Aspicilia esculenta is a vagrant desert lichen of Iran and Northern Africa. It is the most likely candidate for the biblical manna mentioned in Exodus (16:31) and Numbers that was eaten by the Israelites when they wandered the Sinai wilderness for 40 years (Perez-Llano 1944; Brodo et al. 2001). This lichen forms hard, spherical growths that resemble pebbles, usually less than one centimeter in diameter. It is loosely or not at all attached to the substrate and is easily blown around in heavy winds. In violent windstorms lichen thalli can be blown into heaps in lowland areas where morning dew can soften them. Although it is generally found evenly and sparsely distributed, there were large lichen falls were recorded in central Turkey, Armenia, and northern Persia in 1824, 1828, 1829, 1846, and 1890. In some fall events lichens have piled up to 20 to 30 cm high, and because they sometimes occurred during famines they were appreciated as a famine food (Crum 1993).
This lichen is generally thought to be edible. Brodo et al. (2001) states that people in west central Asia are known to have eaten it, at least in times of famine. Perez-Llano (1944) and Uphof (1959) both state that it is still eaten by some desert tribes, being ground mixed with meal to one-third its weight. According to Nelson (1951), it is gathered by the Tartars and made into earth bread. Crum (1993) stated that the lichen is mixed with flour and made into bread in the steppes of southern USSR. Crum also says that it was occasionally eaten in North America as an ingredient in bread, eaten raw, or eaten parched with or without oil. And according to Crum the lichen was used in Libya as famine food during WWII, and that Alexander’s army escaped starvation in 330-327 BC in Persia by eating it.
Crum (1993) also mentions several other human uses for Aspicilia esculenta. It was mentioned as an ingredient to make wine and medicinal compounds in Arabic writing in the 9th to thirteenth centuries. And in Cyrenaica in the 11th century it was collected and fermented with honey as a drink.
In some regions Aspicilia esculenta is also used as forage for sheep and goats, especially in times of drought (Brodo et al. 2001; Crum 1993). Libyan shepherds refer to Aspicilia esculenta as and often graze sheep on it in droughts (Crum 1993). They may erect cairns to help locate particularly good lichen patches, and sometimes harvest the lichen to bring it back to their livestock (Crum 1993). The Bedouin sheep herders in Libya refer to the lichen as TorbaTrub and also use it as forage for their goats and sheep (Crum 1993). Unlike the Libyans, Bedouin don’t just use Aspicilia esculenta in droughts, and they claim that all a sheep needs to survive is Trub and water (Crum 1993).
The manna in the bible is described as a small, round thing. It was as small as hoar frost on the ground, resembled coriander seed, and was white. It was baked to be eaten. This could have been inspired by the lichen Aspicilia esculenta. Currently, however, this lichen does not grow in Sinai. And as Crum (1993) points out, it is unlikely that this lichen supported all of the children of Israel for 40 years, as is suggested in the books of Exodus and Numbers. But the lichen would quite likely be nutritious if properly prepared, as it was found to be 23% carbohydrate and does not contain any secondary lichen compounds that make most lichens bitter and mildly toxic. This is contrary to Crum’s (1993) conclusions, but he was basing his analysis on uncooked lichen when almost all accounts clearly show that Aspicilia esculenta was cooked before being used.
Several other closely related species of Aspicilia grow in the same area and are often referred to as Aspicilia esculenta. These species are Aspicilia jussufii, Aspicilia vagans, and Aspicilia fruticulosa (Crum 1993). As well, another related species Aspicilia hispida has a similar growth form and is found on dry prairies in B. C., Alberta, and northwest U. S. A. (Brodo et al. 2001). Crum (1993) reports on different chemical analyses of Aspicilia esculenta. Two different nutrient analysis have shown that the lichen contains 23% starch and 66% calcium oxalate, or 11% starch and 60% calcium oxalate. The carbohydrates are mostly lichenin and there is no isolichenin. The lichen doesn’t contain detectable amounts of any secondary lichen compounds. According to Crum (1993), the calcium oxalate probably accumulates because the lichen secretes oxalic acid from its hyphae and causes calcium oxalate to form as an insoluble extracellular deposit.