fruit of Ullucus (Basellaceae), an old enigma

The fruit of the cultivated ulluco (Ullucus tuberosus Loz.) has been referred to in the literature either as non-existing or as a berry, seldom as a dry fruit. The fruit of this species as well as the genus is described here for the first time, and is shown to be a dry and indehiscent nutlet of an obovate shape and bilaterally symmetrical cross-section. The thin testa of the seed is immediately inside the thickened fruit wall. The embryo is strongly curved and encircles the relatively scanty perisperm.