46 Excerpta Botanica. 



membranacea translucida cinctse (excepta specie unica, cui samara, 

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

 strobilinis obtectse. 



Arbores v. frutices. Rami teretes v. obsolete angulati. Gemmae 

 perulatse. Folia serrata, v. crenata, v. nonnimquam (variatione) 

 pinnatifida, baud persistentia, petiolata (plerumque brev4) : floralia 

 gemina v. subrosulata ; turionalia floralibus majora et saepe forma 

 alien a, baud raro angulata. Floratio vernalis, foliorum evolutione 

 cosetanea. Amenta e gemmis perulatis orta : mascula jam exeunte 

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

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

 pliis minusve 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. Pterocaryon, Spach. 

 Samarse ala membranacea cinctse. 



* Strobili pedunculati, penduli ; squamis semper trilohis, tricarpis, sa- 

 maras late alatas per maturationem obtegentihus. 



B. ALBA, Linn. — Trunco arboreo : epidermide nive^ (rariiis fused 

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

 ramisque ssepiiis pendulis. Foliis biserratis, v. insequaliter serratis, 

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

 tatis, basin versus integerrimis, obliqu^ truncatis v. cuneatis, v. 

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

 vellis viscosis ; adultis supra saturate, subtiis pallid^ viridibus. 

 Strobilis cylindraceis, elongatis, crassis : squamarum lobis dissi- 

 milibus, ssep^ 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 abbreviato, nunc plus minusve elongato. 

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

 V. oblongo-obovato) longioribus ; dupl5 triplove (rariiis parum) 

 latioribus. 



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



— Betuta pendula, HofFm. — 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. hirta. 

 (i. populifolia. — Betula populifolia, Willd. — Mich. fil. ! Arb. ii. 



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

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

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

 ined. — Foliis longitis cuspidato-acuminatis ; caeterum 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 



