I found a reference to a type of edible gall that grows on sage plants in Crete, and is sold as a sweet in markets there. Can you tell me what species of sage that might be, and is it something we can grow in the Pacific Northwest? Will it develop tasty galls here?
It seems very likely that the species of sage is Salvia pomifera. That species name (‘fruit-like’) refers to the apple- or fruit-shaped galls. The webpage of Flora of Israel has a feature article by Professor Avinoam Danin on this type of Salvia that does indeed grow in Crete. He mentions another Cretan species that produces fruit-like gall structures, Salvia fruticosa.
Flowers of Crete (John Fielding and Nicholas Turland, Kew, 2005) describes these two common shrubby sages found in Crete. “They share similar habitats, pine woodland, olive groves, scrub, garrigue, and rocky places,” though S. fruticosa is mainly found in the lowlands, while S. pomifera is more montane. Salvia fruticosa (faskomilo in Greek) is used in herbal tea, but “both species produce globose stem galls, which are eaten raw (including the insect larvae inside) by Cretan children.” (The authors do not say why children–rather than adults?–prefer this treat!)
According to Greek horticulturist and Salvia expert Eleftherios Dariotis, “Salvia pomifera is the one that produces most galls and people like to eat them. Their taste is like a sagey apple and they are crunchy in texture. S.fruticosa produces galls as well, but not as often.”
In the Middle East, there is another species of sage that produces edible galls. Salvia dominica goes by the common name Bedouin peach, or khokh, because the galls it develops are fuzzy like the fruit.
The galls aroused curiosity among plant explorers in centuries past. 16th century French botanist Pierre Belon described them as “covered with hair and sweet and pleasant to the taste. They were collected at the beginning of May and sold by the people of Candie [Candia?] to neighboring villagers.” [Source: The American Naturalist, Volume 52 February-March 1918]
During his travels in Crete, the 17th/18th century French botanist Joseph Pitton de Tournefort came across a sage he called ‘Salvia cretica frutescens pomifera,’ a shrubby Cretan sage that bore apple-like fruit. An article in Saturday Magazine (vol. 16, 1840) mentions his observation of large galls “caused by the punctures of insects; these galls are firm, fleshy, semi-transparent tumours, swelling out from the branches of the plant, and supposed to be produced in the same manner as oak apples, by the puncture of an insect of the Cynips genus. They form an article of ordinary sale in the markets, and are called sage-apples. When preserved with sugar, these apples are regarded as a great delicacy.”
Salvia pomifera will grow in USDA hardiness zones 7-10, and both Salvia fruticosa and Salvia dominica will grow in USDA hardiness zones 8-11. To me, that sounds like potentially marginal hardiness given our tendency for wet (Salvia-rotting!) winters.
I have a feeling that you would not have much luck in attracting the right species of Cynipid gall wasp to Pacific Northwest-grown Salvias. The Aulax species of gall wasp is what causes the galls found on sage species growing in the Mediterranean region. According to the Field Guide to Plant Galls of California and Other Western States by Ron Russo (University of California Press, 2006), the gall wasps which may affect Salvia species in California and other western states are Rhopalomyia species. The galls they form are tubular in shape, and not fruit-like in appearance. There is no documentation on their taste.