52 Elementary Species 



to be too large to constitute species. Hence the 

 poljTQorphous genera, concerning the syste- 

 matic subdivisions of which hardly two authors 

 agree. Brambles and roses are widely known 

 instances, but oaks, elms, apples, and pears, 

 Mentha, Prunus, Vitis, Lactuca, Cucumis, Cu- 

 curhita and numerous others are in the same 

 condition. 



In some instances the existence of elementary 

 species is so obvious, that they have been de- 

 scribed by taxonomists as systematic varieties 

 or even as good species. The primroses afford 

 a widely known example. Linnaeus called them 

 Primula veris, and recognized three types as 

 pertaining to this species, but Jacquin and 

 others have elevated these subspecies to the full 

 rank of species. They now bear the names of 

 Primula elatior with larger, P. officinalis with 

 smaller flowers, and P. acaulis. In the last 

 named the common flower-stalk is lacking and 

 the flowers of the umbel seem to be borne in 

 the axils of the basal leaves. 



In other genera such nearly allied species are 

 more or less universally recognized. Galium 

 Mollugo has been divided into G. elatum with a 

 long and weak stem, and G. erectum with 

 shorter and erect stems ; Cochlearia danica, an- 

 glica and officinalis are so nearly allied as to be 

 hardly distinguishable. Sagina apetala and pat- 



