The second name is always called the specific name, because it shows us that from all other roses our new _Rosa alba_ differs in being white. It is of the genus _Rosa_, but it is also and forever after a recognized member of _Rosa_, to which a specific name has been applied--in other words, _Rosa alba_ is a species of rose. Species are thus plants more like one another than they are like any other member of the genus to which they belong. _Rosa alba_ is a species quite unlike _Rosa lucida_, or _Rosa carolina_, or all the other scores of roses already known or described. At the time of christening _Rosa alba_, we should not only enter its name in a book, as ours would be in a parish register, but do much more than that. We should so carefully describe it and, preferably, illustrate it with a picture that no one coming after could ever mistake _Rosa alba_ for any other rose. It can be readily seen that the christening of new plants is very nearly as serious an affair as christening babies, and furthermore, it is only to be attempted by experts. Because this has not always been done, many plants have been christened two or three times. Of course, these subsequent christenings do not seriously matter, for plants, like ourselves, should have only one specific name, the first applied to them. But their subsequent christenings by the careless and ignorant have enormously increased the difficulty of talking or writing about plants. These spurious names are common throughout the literature of botany and are known as synonyms. The thing to remember about plants, so far as our need for classifying them is concerned, is that they belong to different species which might almost be considered the unit or simplest recognizable category into which they may be sorted. For convenience, we sort species into genera which may well be considered the next highest category in which plants are grouped. The grouping of genera into tribes, of tribes into families, and of families into still larger categories, has nothing to do with their names, but everything to do with our understanding of how they are related to one another, and what these different categories mean in the great collection of plants all about us. In other words, it reduces to a definite system an apparently hopelessly mixed-up mass of plants that, without some contrivance of the sort, would simply be a lot of totally unrelated specimens of plant life. Actually they are grouped in fairly definite categories, some of which are easily recognizable, and all of which fit into that great scheme of nature where everything may seem chaotic, but to the observant it is really a very pattern of order. What it all means and how plants have been grouped into families will be explained, now that we understand how they have acquired their generic and specific names. PLANT FAMILIES AND ORDERS