It seems that you have to be fluent in Latin to be able to speak and understand the language of horticulture.
To hear someone who knows their botanical Latin name several trees and shrubs in rapid succession is like trying to understand a foreign language.  Fear not, for Latin name are not that difficult to master if you start with those plants in your own garden and understand how and why plants are named.
Confusion would absolutely reign supreme if there was no universal system designed for naming plants.  Common names are fine, but only if there is one name for each plant.  For example, if someone asks me if we carry the japonica plant, do they mean Pieris japonica, Kerria japonica, Spirea japonica or Chaenomeles japonica?
Often one plant will have several names.  There is only plant known botanically as Saponaria ocymoides, but some of you may know it as soapwort, while others call it Bouncing Betty.  That is why we have Latin names for plants.
There are two main elements of a plant’s name.  The genus name appears first.  It groups together in a botanical unit all plants with similar properties.  Chrysanthemum, hydrangea, delphinium, clematis and rosa are good examples.  The genus name for the marigold is tagetes.  Tomatoes are in the genus solanum, sharing it with the petunia.
The genus names are a good place to start when learning plant names.  Start with the plants in your own garden and expand your repertoire.
The second name indicates what species the plant belongs to.  In some cases there is only a single species, in others there may be hundreds.
Species names are inspired by several different sources.  Many are named after people.  For example Primula forestii honours plant explorer George Forrest.
Some give clues to where a plant originated.  Iris afghanisa is native to Afghanistan, while Sorbus Americana is found in the United States.  However, Scilla peruviana is not named because it comes from Peru, but because it was brought to England on the ship HMS Peru.
The largest group of species names are descriptive ones, and there is much to learn from these is you are so inclined.  Alba is a widely used name; in Cornus alba it refers to the white berries and in Spirea albiflora it describes the white flowers.
 Juniperus procumbens is a low growing juniper.  Quercus rubra is an oak tree with red leaves.  Larix decidua describes a larch which drops its needles in the fall, while Betula pendula is a birch with long, weeping branches.
 Many of these words are used several times combined with different genus, but there is no confusion because Cornus alba and Betula alba are two entirely different plants.
 A slightly more complicated form uses two-part words in the species name.  Parthenocissus quinquefolia describes quinque (five) and folia (leaf), the five-lobed leaflet of our familiar Virginia creeper.
Viburnum trilobum can be dissected into tre (three) lobum (lobes) to produce a viburnum with three-lobed leaves.  There are 20 to 30 basic “parts” which are often used in combination to describe thousands of plants.
This is probably enough Latin to digest at one sitting and it may seem complex, but it doesn’t take long before even the longest and most obscure plant names become as familiar as rhododendron or poinsettia.