The genus Prunus is variously delimited and divided by systematic botanists. A simple, and from a horticultural point of view, a very satisfactory classification, is to put almonds and peaches in one sub-genus (Amygdalus), cherries in a second (Cerasus), plums and apricots in a third (Euprunus), and to place the racemose cherries and cherry-laurels, usually considered in Prunus, in another genus, Padus. In this division of Prunus into three sub-genera we may assign to each the following characters. A. Leaves convolute, _i. e._, rolled in the bud (showing best in the opening buds).[3] _Euprunus._ Plums and apricots. A.A. Leaves conduplicate, _i. e._, folded lengthwise along the midrib in the bud. B. Fruit more or less dry and hirsute; if juicy or glabrous the blossoms appear long before the opening of the leaves; fruits without stems. _Amygdalus._ Almonds and peaches. B.B. Fruit always juicy and usually glabrous; blooms appearing with the leaves. _Cerasus._ Cherries. Of these several divisions we are here concerned only with Cerasus, to which belong all fascicled cherries, the racemose, or Padus, cherries as yet having little or no value as esculents. The genus Prunus is from year to year being enlarged by the discovery of new species, the additions to Cerasus in particular being numerous. Thus, a decade ago, botanists placed in this sub-genus, at the outside, not more than a score of species but Koehne, the most recent monographer of Cerasus, describes 119 species. Of Koehne's species at least a dozen are more or less cultivated for their fruits and a score or more are grown as ornamentals. The following species are listed by Koehne:[4] SPECIES OF CHERRIES Div. I. TYPOCERASUS Koehne. Sect. 1 CREMASTOSEPALUM Koehne. Subsect. 1. MAHALEB Koehne. _Cerasus_ sect. _Mahaleb_ Roemer. _Fam. Nat. Syn._ =3=:79. 1847. _Prunus_ subgen. _Cerasus_ sect. _Mahaleb_ Koehne. _Deutsche Dendr._ 305. 1893. Ser. 1. EUMAHALEB Koehne. =1. Prunus mahaleb= Linnaeus. _Sp. Pl._ 472. 1753. Europe, Western Asia. Ser. 2. PARAMAHALEB Koehne. =2. Prunus mollis= Walpers. _Rep._ =2=:9. Western North America. =3. Prunus emarginata= Walpers. _Rep._ =2=:9. Western North America. _Cerasus californica_ Greene. _Fl. Francis_ =1=:50. =4. Prunus pennsylvanica= Linnaeus. _Syst._ ed 13 Suppl. 252. Eastern North America. Subsect. 2. EUCERASUS Koehne. _Prunus_ sect. _Eucerasus_ Koehne. _Deutsche Dendr._ 306. 1893. =5. Prunus fruticosa= Pallas. _Fl. Ross._ =1=:19. 1784. Europe to Siberia. =6. Prunus acida= C. Koch. _Dendr._ =1=:112. 1869. Southern Europe. =7. Prunus cerasus= Linnaeus. _Sp. Pl_. 474. 1753. Europe, Western Asia.