Greengages (subspecies of Prunus), sometimes Americanized as Green Gage, are a European plum sometimes found in the wild as an escapee from cultivation. Imported into England by Sir Thomas Gage (whence its English name), it has been grown in America since the days of Washington and Jefferson. They produce a small, oval, yellowish-green fruit with juicy, smooth-textured, amber flesh. They have a rich, confectionary flavor that diminishes somewhat after generations in the wild, but even then they are quite sweet.
Most wild greengage trees grow from 5 to 9 feet high with low branches and rounded head. They have attractive blossoms, deep gree foliage, and are quite hardy. They are self-fertile but still are known to cross with other Prunus species if in close proximity.
Wild greengages make an excellent wine that requires considerably less aging than plum, damson, sloe, or cherry wines.
Put 1/2 gallon water on to boil. Meanwhile, mince the barley and wash, sort, destem, destone, and chop the fruit, saving all juice. Transfer fruit and barley to primary and add boiling water, cover and allow to cool to lukewarm. Add crushed Campden, recover and wait 12 hours. Add pectic enzyme, recover, and wait 4 days. Strain fruit and barley through nylon straining bag and press well to extract most juice. Add half the sugar and the yeast nutrient, stirring well to dissolve, then transfer to secondary and add yeast. Cover with sterile cloth secured with rubber band. After 7 days of fermentation, add remaining sugar, stir well with sterile rod to dissolve, and fit airlock. Rack after one month, top up and refit airlock. Repeat after wine clears. Set aside for 4 months. Stabilize, wait 10 days and rack into bottles. This wine can be consumed young but improves if stored one year. [Adapted recipe from C.J.J. Berry's First Steps in Winemaking]