White varieties of species with red or blue flowers are the most common instances. If the species has a compound color and if only one of the constituents is lost, partially colored types arise as in _Agrostemma Coronaria bicolor_. Or the spots may disappear and the color become uniform as in _Gentiana punctata concolor_ and the spotless Arum or _Arum maculatum immaculatum_. Absence of hairs produces forms as _Biscutella laevigata glabra_; lack of prickles gives the varieties known as _inermis, as for instance, _Ranunculus arvensis inermis_. _Cytisus prostratus_ has a variety _ciliata_, and _Solanum Dulcamara_, or the bitter-sweet, has a variety called _tomentosum_. The curious monophyllous [126] variety of the strawberry and many other forms will be discussed later. To enlarge this list it would only be necessary to extract from a flora, or from a catalogue of horticultural plants, the names of the varieties enumerated therein. In nearly every instance, where true varieties and not elementary species are concerned, a single term expresses the whole character. Such a list would also serve to illustrate the second point since the same names would recur frequently. Long lists of varieties are called alba, or inermis, or canescens or lutea, and many genera contain the same appellations. In some instances the systematists use a diversity of names to convey exactly the same idea, as if to conceal the monotony of the character, as for instance in the case of the lack of hairs, which is expressed by the varietal names of _Papaver dubium glabrum_, _Arabis ciliata glabrata_, _Arabis hirsuta glaberrima_, _Veronica spicata nitens_, _Amygdalus persica laevis_, _Paeonia corallina Leiocarpa_, &c. On the contrary we find elementary species in different genera based on the greatest possible diversity of features. The forms of _Taraxacum_ or _Helianthemum_ do not repeat those of _Draba_ or _Viola_. In roses and brambles the distinguishing features are characteristic of the type, as [127] they are evidently derived from it and limited to it. And this is so true that nobody claims the grade of elementary species for white roses or white brambles, but everyone recognizes that forms diverging from the nearest species by a single character only, are to be regarded as varieties.