46 Excerpta Botanica. 



membrauacea translucida cinctse (excepta specie unica, cui samara, 

 V. potius nucula, aptera, margine incrassata), plerumque squamis 

 strobilinis obtectfe. 



Arbores V. frutices. Rami teretes v. obsolete angulati. Gemma; 

 perulatee. Folia serrata, v. crenata, v. nonnunquam (variatione) 

 pinnatifida, baud persistentia, petiolata (pleriimque breve) : floralia 

 o-emina v. subrosulata ; turionalia lioralibu? majora et ssepe forma 

 aliena, baud raro angulata. Floratio vernalis, foliorum evolutione 

 cocEtanea. Amenta e gemmis perulatis orta : mascula jam exeunte 

 jestate prseterita evoluta, propter perulas fugaces mox nuda, sub an- 

 thesi pendula v. nutantia : squamis ciliolatis, plerumque basi et apice 

 plus miniisve acuminatis. Foeminea sub anthesi erecta v. resupinata. 

 Strobili erecti v. penduli, rachi gracili v. fere filiformi. Ramuli fruc- 

 tiferi maturatione peracta baud emortui. 



Sectio I. Fterocaryon, Spach. 

 Samarse ala membranacea cinctse. 



* Strobili pedunculati, penduli ; squamis semper trilobis, tricmpis, sa- 

 maras late alatas per maturationem obtec/entibus. 



B. ALBA, Linn. — Trunco arboreo : ej^idermide nivea (rarius fusca 

 aut aureo-fusca). Ramulis novellis resinoso-verruculosis, demiim 

 ramisque ssepitis pendulis. Foliis biserratis, v. inaequaliter serratis, 

 V. grosse crenato-dentatis, cuspidato-acuminatis, v. acutis, punc- 

 tatis, basin versus integerrimis, oblique truncatis v. cuneatis, v. 

 rotundatis, v. cordatis ; turionaiibus cordato-ovatis, angulatis ; no- 

 vellis viscosis ; adultis supra saturate, subtus pallide viridibus. 

 Stx'obilis cylindraceis, elongatis, crassis : squamarum lobis dissi- 

 milibus, ssepe invicem incumbentibus : lateralibus suborbicularibus, 

 V. oblique ovatis, v. semi-orbicularibus, v. subcultratis, obtusis, 

 nunc terminal! parallelis, nunc divaricatis, nunc deflexis ; lobo 

 terminali ovato, v. ovato-oblongo, v. oblongo, v. deltoideo, obtuso, 

 v. acutiusculo, nunc abbreviate, nunc plus minusve elongate. 

 Samara obcordato- v. obreniformi-biloba : alis loculamento (obovato 

 v. oblongo-obovato) longioribus ; duplo triplove (rariiis pariim) 

 latioribus. 



a. vulgaris. — Betula alba, auctor. plur. — Betula verrucosa, Ehrh. 



— Betula pendula, HoflFm. — Foliis floralibus rhomboideis, v. deltoi- 

 deis, V. ovatis, v. cordatis, acuminatis, longe petiolatis, ramulisque 

 annotinis glaberrimis. Pedunculis fructiferis petiolis plerumque 

 brevioribus. — Surculorum folia ssepissime pubescentia v. liirta. 

 (j. populifolia. — Betula popuUfoUa, Willd. — Midi. fil. ! Arb. ii. 



p. 139, cum fig. (forma grandifolia). — Wats. Dendr. Brit. tab. 

 151 ! (forma foliis minoribus). — Betida acuminata, Ehrh. Beytr. 

 — Betula lenta, Duroi (non Linn.). — Betula cuspidata, Schrad. ! 

 ined. — Foliis iongiiis cuspidato-acuminatis ; cseterum var. vulgari 

 omnino similis, simulque inter stirpes Europseas passim occur- 

 rens. (V. v. c. et s. sp.) 



y. Dalecarlica. — Betula alba Dalecarlica, Linn, — Betula hy- 



brida, Blom. in Act. Holm. 1786, p. 168, tab. 6. fig. B. (non 



