462 WILSON EXPEDITION TO CHINA 



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CONSPECTUS ANALYTICUS BETULARUM ASIAE ORIENTALIS 



NEC NON HIMALAYAE. 



Amenta fructifera ad 2-4 racemoso-conferta t. soHtaiia, pendula, longe et anguste 



cylindrica; lobi laterales bractearum valde reducti v. in B. Maximowicziana 



tantum distinctiores; samararum alae latae, bractcas lateraliter superantes v, 



nuculis fere triplo latiores. Folia muIti(9-13)-costata. 



Sect. 1. ACUMINATAE. 



* Amenta fructifera ad 2-4 racemoso-conferta (rarius interdum abortu soUfcaria). 



Lobi laterales bractearum distinct!, medio circiter dimidio breviores; sa- 

 mararum alae nuculo fere triplo latiores. Folia magna, late ovata, basi 

 profunda cordata; petioli 2.5-4 cm. longi . . . ,1. B. Maximovicziana. 

 Lobi laterales bractearum reducti. Folia ovato-oblonga v. basi baud cor- 

 data; petioli 1.2-2(-2.2) cm. longi. 

 Ramuli hornotini petioli(iue distincte fiavo- v. griseo-tomentelli et etiam 

 pedunculi et saepissime costa paginae inferioris f oliorum eod^n tomento 

 obtecta. Folia late ovata v. ovato-oblonga, basi rotunda v. leviter 

 cordata, satis subito acuminata, dentibus plus minusve distantibus. 



2. B. cylindrostachya. 



Ramuli hornotini petlolique breviter pubescentes v. pleraque tantum 

 pilosi V. subglabri, saepe glanduliferi (pedunculi tantum saepe dis-tinctius 

 tomentelli). Folia ovato-oblonga, sensim acuminata saepe caudata, 

 basi rotundato-truncata v. subacuta, dentibus plus minusve adpressis. 



3. B. alnoides, 



** Amenta fructifera solitaria; lobi laterales bractearum reducti. 



Petioli 0.8-2.5 cm. longi. Amenta fructifera 3.5-11 cm. longa; bractearum 

 lobus medius elongatus lateralibus parvis v. minimis valde longior.^ Folia 

 pleraque plus quam 6 cm. longa 4. 5. luminifera. 



Petioli 6-8 mm. longi. Amenta fructifera 3-4 cm. longa; bractearum lobus 

 medius satis brevis. Folia tantum 5-6 cm. longa . . . 5. B. Baeumkeri. 



Amenta fructifera solitaria (rarissime bina) pendula, patentia v. erecta; lobi 

 laterales bractearum distinct!; samararum alae nucula vix latiores, saepe an- 

 gustissimae; bracteae samaras occultantes. ^ . r 



• Amenta fructifera erecta, pleraque subglobosa, ovata v. anguste elliptica (in 



10. B. Schmidtii cylindrica); bractearum lobi laterales fere semper erectae 

 V. erec to-pat en tes medio distincte producto plus minusve breviores. Folia 

 nervis lateralibus supra plus minusve impressis (6-)7-14 instructa. (Confer 



etiam 25. B. davuncam) Sect. 2. COSTATAE. 



t Samararum alae satis distinctae, nucula circiter Hj rarius ad 34 angustiores; 

 amenta fructifera ovato-cylindrica v. sub cylindrica, 2-3-pl_o longiora 

 quam lata, pedunculo satis distincto et tenui suffulta (v. folia tnangu- 



laria versus basim latissima; vide 6. B, Ermanii). 



Subsect. a. Ermanianae. 



Folia plus minusve triangularia v. ovato-triangularia, versus basim latis- 

 sima, basi truncata, plus minusve cordata v. rarius subrotunda. 



Q, B. Ermami. 



Folia ovata, ovato-oblonga v. ovato-rotunda, medio v. versus medium 

 (rarius supra medium) latissima, basi saepissime rotunda v. subacuta, 

 interdum cordata. 

 Nervi laterales foliorum majorum utrinque &-9. . 7. B. Jacquemontit. 



Nervi laterales foliorum (&-) 10-14. 



