The south-east Asian plant known as lemba has been referred to briefly on this site before, as a member of the family Hypoxidaceae. As noted in that post, it has been through a couple of names over the years: some sources will refer to it as Molineria latifolia, while others will call it Curculigo latifolia. The genera Molineria and Curculigo have been distinguished based on the presence of beaked (Curculigo) or unbeaked (Molineria) fruits and seeds, but the phylogenetic analysis of Hypoxidaceae by Kocyan et al. (2011) did not find this character to correlate with phylogeny. They therefore proposed to stop recognising the two genera as distinct, merging all species under Curculigo.
Curculigo latifolia is one of the largest species in the Hypoxidaceae. It is mostly found growing in damp, shaded locations, and the long-petioled leaves coming from an erect central rhizome can be a metre in length. Its small yellow flowers are placed at the base of the plant, at ground level; this distinguishes this species from various large orchid species found in the same region that may also be referred to as 'lemba' (or 'lumbah', or some other spelling/linguistic variant). The flowers give rise to small white berries, about an inch in size, with a distinct beak.
Uses of this plant were recently reviewed by Lim (2012). The leaves provide a strong, lightweight fibre that is used to make nets, rope and cloth. The roots are brewed to treat various illnesses. However, the feature of this plant that has received the most attention in recent years is the fruit. These are edible, and are said to taste a bit like a sweet cucumber. The reason they have aroused interest, though, is that after eating one, anything else eaten within the next ten minutes or so will also taste sweet. This effect has been traced to a protein in the fruit, variously called neoculin or curculin, that has been reported to have several hundreds times the sweetness relative to weight of sucrose. Curculin has consequently been proposed as a potential low-calorie sweetener (to which I say, I'm sure it can't possibly taste worse than stevia), though one limitation is that the protein becomes denatured at temperatures above fifty degrees and loses its sweetening properties. As yet, though, it doesn't look like lemba sweetener has made it onto the commercial market.
Kocyan, A., D. A. Snijman, F. Forest, D. S. Devey, J. V. Freudenstein, J. Wiland-Szymańska, M. W. Chase & P. J. Rudall. 2011. Molecular phylogenetics of Hypoxidaceae—evidence from plastid DNA data and inferences on morphology and biogeography. Molecular Phylogenetics and Evolution 60 (1): 122-136.
Lim, T. K. 2012. Edible Medicinal and Non-Medicinal Plants, vol. 4. Fruits. Springer.