226 WILSON EXPEDITION TO CHINA 



SUBGENERIS CERASI SYSTEMA NOVUM. 



Tliis subgenus can be divided in two very natural groups: 



Grex I. TYPOCERASUS. Gemmae supra quamvis folii cicatricem solitariae, 

 hae floriferae, illae ramum foliatum promittentes: plantae triaxiflorae. (Gemmae 

 saepe in ramis abbreviatis confertae.) Petioli longiusculi v. longi. 



If, as usual, the branch of the previous year is considered as axis I., the axis of 

 the bud or of the inflorescence will be axis II., exactly as in the subgenus Padus, 

 while the pedicel itself, even if the inflorescence is reduced to one flower, is to be 

 called axis III. The plants therefore are tri-axial. 



In such a polymorphous group as Cerasus it is not surprising that transitional 

 forms occur. Thus I have observed in P. stipulacea and P. microlepis occasional 

 ternate buds after the type of Microcerasus. Both species, however, belong 

 according to their other characters to Typocerasus. 



Grex II. MICROCERASUS. Gemmae sub florationis tempore typice ternae, 

 media typice ramum foliatum promittens (saepissune vero abortiva), laterales 

 floriferae; plantae quadraxiflorae. Petioli insigniter breves (exc. in P. pumila 

 affinisbusque, ubi petioU longiuscuh). 



The two lateral buds originate in the axils of the lowest pair of scales of the 

 middle bud, their axes, therefore, become axes of the third order, while the pedi- 

 cels will be axes of the fourth order. The plants, therefore, are quadri-axial. 



Grex I. TYPOCERASUS.i 



Sepala reflexa Sect. 1. CREMASTOSEPALUM. 



Sepala erecto-patula v. rarius patentia (sed cf. P. cerasoidem, ubi sepala interdum 

 reflexa videntur) Sect. 2. PSEUDOCERASUS. 



Sect. 1. CREMASTOSEPALUM. 



FoUorum dentes obtusae v. rotundatae v. emarginatae, glandula saepissime oblique 

 V. basaUter juxta dentem sequentem inserta v. rarius apicali. 

 Dentes brevissimae. Involucrum (i. e. inflorescentiae perulae basales) ante 

 anthesin deciduum. (Europa, Asia occidentalis, America borealis.) 



Subsect. 1. MAHALEB. 

 Folia suborbicularia. Petala glaberrima. Drupa nigra v. sordide lutes- 



cens. (Europa, Asia occidentalis.) Ser. 1. Eumahaleb. 



Folia longiora angustiora. Petala extus pilosa, nonnisi in P. emarginata 



glabra. Drupa rubra. (America borealis.) . . . Ser. 2. Paramahaleb. 



Dentes bene evolutae. Involucrum sub anthesi arete adhaerens magnum v. 



majusculum. (Europa, Asia occidentalis.) . . . Subsect. 2. EUCERASUS, 



Fohorum dentes acutae v. acuminatae v. subito brevissime cuspidatae glandula 



apicali. 



Petala baud emarginata. 



Bracteae herbaceae saepe majusculae, sub fructu persistenteg. Florea coae- 

 tanei. 

 Racemi breves v. longiusculi, (3-)4-9-flori, densi- v. laxiflori, pedunculati. 

 (China, Japonia usque ad terram Amurensem et insulam Saghalin.) 



Subsect. 3. PHYLLOMAHALEB. 



* Several species of which the flowers are not known can be referred to certain 

 groups only according to their general character. Therefore a revision of these 

 species will be necessary when complete material is available. 



