The problem isn't with either the gardener or the employee. More likely, it's a communication issue-many plants share the same common names, or the same plant might be known by several different common names in various regions of the world.The solution to the naming issue was actually presented centuries ago, when the system of binomial nomenclature was developed the Swedish botanist Carolus Linnaeus and then widely adopted. This system relied on two-part Latin names for each plant. The first name would describe the plant's genus and the second its species. The global adoption of binomial nomenclature meant that people asking for a Dracaena draco in Indonesia would be assured they are talking about the same plant as people discussing Dracaena draco in London or New York or Nepal.
While it undoubtedly furthered science, binomial nomenclature is infinitely helpful to the amateur biologist or plant collector. It reduces confusion and guarantees you'll get the plant you want. Thus, it's strongly advised that beginners to gardening begin to learn the Latin names of plants as soon as possible.
Aside from reducing confusing, the nomenclature system is valuable because it also provides a great deal of information about the plant you are buying. A typical Latin plant name will have two parts: the genus and species, as mentioned. When written, the genus should always be capitalized and the species will be lowercase. However, beyond that, there may be other words that yeild more information. For example:Dracaena deremensis 'Warneckii'
In this case, the third word describes the cultivar of the main species. So this plant would be a D. deremensis 'Warneckii'cultivar. A cultivar is simply a strain of a species that has been carefully bred to encourage certain traits that are naturally present in the species. For example, a breeder might, over time, breed a certain plant to encourage larger, green leaves, crossing and recrossing parents with larger, green leaves back on themselves. Over time, once this trait has been stabilized and it's possible to reliably produce spcies of this plant with larger, green leaves, a cultivar name might be assigned to the plants. Note that the cultivar name is surrounded in single quotes and no italicized, whereas the genus and species names are still italicized.You might also see a plant name that looks like this:
Citrus x citrofortunella mitis
This formulation, with an x in the name, denotes a hybridized plant. In this case, the plant is a hybrid between the mandarin orange and kumquat, within the genus x citrofortunella. Hybrids are almost always created by breeders looking to stengthen and reinforce certain desirable qualities in parent plants of different species. It's important to note that only closely related species can be successfully crossed to produce new hybrids, and even then, in most cases the offspring will be sterile or will bear seeds that don't produce true to the parent (they might grow plants that are strongly associated with one of the parent species of the other). True hybrids in nature are exceedingly rare.
It's valuable to note that, while this system is used to classify all plants and animals worldwide, the naming conventions behind orchids can be somewhat more complex. This is due in part to the sheer number of orchid species and their complexity, and the very active breeding community that has, over the century, produced tens of thousands of named cultivars and hybrids.