Molecular studies will never be a "cure all" for what ails us, taxonomically speaking. DNA-level understanding (or anatomical, phytochemical, phytogeographical, etc.) is useless absent the wider context of *actually* *knowing the plants*. This is a universal need to which science is immeasurably instructive, but ultimately knowing plants and their names is not the province of any one discipline. This discussion reminds me of the joke about the student busy sequencing various samples who would not recognize one of his subjects in the field if he tripped over it. This is not as far-fetched as it sounds in some cases. As Tim indicates, molecular studies are dependent on sampling range and quality and there are natural limitations to sampling known taxa. For example, a plant only known from the type, assuming DNA can be extracted, tells us nothing of infraspecific variation or even if the specimen is representative of that taxon. These studies are certainly of great importance and have gone a long way to providing insight into the relationships of many groups, but as far as circumscribing species, I think population level investigations will become increasingly useful and interesting. Before we can answer "What is a species?" we need to know "What is a population?" Dylan