154 JOURNAL OF THE ARNOLD ARBORETUM [vol. vi 



venis utrinque 4-6 elevatis; petioli 2-5 mm. longi, dense villosi. Flores 

 subsessiles, fasiculati in paniculis lateralibus interdum terminalibus 7-12 

 cm. longis; rachis dense villosa; calyx campanulatus, plerumque distincte 

 dentatus dentibus ovato-triangularibus acutis vel acuminulatis ; corolla 

 tubo gracili 5-7 mm. Ion go, lobis ovatis 2-3 mm. longis acutiusculis inter- 

 dum cucullatis; stamina paullo infra faucem inserta antheris pallidis faucem 

 non superantibus. 



Yunnan: undergrowth of the mountains at Tcha-ho; alt. 2600 m., E. E. 

 Maire, July, 1914 (tyj)c; no. 16!), Herb. Roy. Botanic Garden, Edinburgh); 

 thickets of the mountains at Te-long-tsin, alt. 3000 m., E. E. Maire, June 



(no. 503, Herb. Arnold Arboretum). 



This species is most closely related to S. Potaninii Schneid., which 

 differs in the not distinctly rugulose leaves, less densely pubescent branch- 

 lets and inflorescence, in the minute appressed pubescence of the usually 

 truncate calyx, in the longer and narrower corolla-lobes and in the stamens 

 being inserted much below the mouth. The flowers of the specimen from 

 Tcha-ho are according to the collector rose-violet, while those of the speci- 

 men from Te-long-tsin are described as white. 



AMELASORBUS, A NEW BIGENERIC HYBRID. 



Alfred Rehder. 



Amelasorbus (Amelanchier X Sorb us), gen. hybr. nov. 



Intermediate between the parents: from Amelanchier the hybrid differs 



chiefly in the partly pinnate leaves, the paniculate inflorescence and in 



the free styles, while from Sorbus (§ Aucuparia) it is distinguished by the 

 mostly undivided leaves, only partly more or less pinnate or pinnately 

 lobed below the middle, in the secondary axes of the compound in florescence 

 being racemose, not corymbose, in the oblong petals, in the usually 5 styles 

 and in the presence of imperfect false septa in the fruit. Only known in 

 the following form: 



Amelasorbus Jackii (Amelanchier florida X Sorbus sitchensis), hybr. 

 nov. 



Frutex rohustus, 2-3 m. altus; ramuli robusti, initio laxe villosi, citis- 

 sime glabri, purpurci vel purpurascentes, vetustiores rubro-fusci, luciduli; 

 gemmae oblongo-ovoideae, (i S mm. longae, acutae, perulis exterioribus 

 4-0, apice et partim ad marginem leviter lanuginosis ceterum glabris 

 purpureo-brunneis. Folia ovalia vel elliptica, rarius oblongo-elliptica, 

 3.5-6 cm.longa, apice rotundata vel acutiuscula, basi rotundata vel cordata 



grosse dentata dentibus late ovatis acuminulatis, ad basin pleraque Integra, 

 initio laxe villosa, cito glabra, nervis utrinsecus 10-12, pleraque indivisa 

 sed pauca basi lobis vel foliolis 1-3 instructa; petioli 1-25 em. longi, glabri; 

 folia turionum oblongo-elliptica vel ovato-oblonga, 5-10 cm. longa, 



