Diocoreophyllum cumminsii , 10 seeds /$6, shipping /$10, Phyto certificate /$12

This astounding, smallish climbing plant produces slender stems from an underground tuber. The small, green flowers are followed by pea-sized, pinkish red fruits that have a firm, slightly crunchy coat and an intensely sweet, mucilaginous layer around the single seed. That layer is considered to be the sweetest known naturally occurring substance, perhaps as much as 3000 times sweeter than table sugar. Even though the Serendipity Berries are really too sweet to enjoy more than a single one, they would have enormous potential as a carbohydrate-free sugar substitute, similar to Synsepalum dulcificum. The fruit stores well at room temperature for several weeks. The underground tuber is also said to be edible. Dioscoreophyllum cumminsii is native to forests in tropical Africa, where it is also cultivated for its fruit. Fresh seeds must be cured dry for at least 3 to 4 months in order to germinate well.