r 



BETULACE,E (Skan), 573 



Order CXXIV, BETULACEJE. 



By S. A. Skan". 



Flowers monoeciousj the male in pendulous catkins, the female in 

 erect or pendulous catkins or in budlike heads. Male flowers : 

 Periantli simple, membranous, 4- or fewer lobed, sometimes 0. 

 Stamens 2-12; filaments free, usually as Mell as the anthers more 

 or less split ; anther-cells 2, erect, parallel, sometimes pilose at the 

 apex, dehiscing longitndinall3\ Ovary rudiment none. Female 

 flotvers: Perianth minute or sometimes nearly completely adnate to the 

 ovary, often 0, Ovary inferior, crowned with the annular or toothed 

 perianth or naked, 2-ceIled, often more or less laterally compressed ; 

 styles 2, free, filiform. Ovules 1 in each cell, pendulous, anatropous, 

 provided with 1 integument. Fruit a nut or nutlet, ovoid-globose 

 or usually laterally compressed, sometimes winged, more or less 

 enveloped in the variously connate often much accrescent herbaceous 

 membranous or woody bracts and bracteoles. Seed usually soli- 

 tary by abortion, exalbuminous ; testa membranous ; cotyledons 

 fleshy, smooth, rugose or ruminate ; radicle short, superior. 



Trees or shrubs ; leaves alternate, pinnately veined, toothed, sometiines more or 

 less lobed, rarely entire ; stipules caducous ; inflorescences termin.il or lateral ; 

 flowers 1-3 in tlie axils. of scale-like or sometimes leafy bracts, appearing in spring 

 with or before the leaves or rarely in the autumn, 



DiSTKlB. Genera 6 and species about 80, cbiefly in Europe, Temperate Asia 

 and North America, 1 in North and South Africa and a few in Central and South 

 America, 



Betulacem is here defined as in Winkler's ^ilonograph in Engler's Das Pflanzen- 

 reich. It comprises the tribes BetuJex and Corylem of Cwpuliferm in Bentham 

 and Hooker's Genera Plantarum. 



L ALNUS, Linn. 



/ 



3-5, more or less united to the bract. Perianth sessile, deeply 

 4-lobed. Stamens 4, opposite to the perianth-lobes ; filaments very 

 short, undivided ; anthers dorsifixed, ovate, not pilose at the apes. 

 Female fl^oicers usually 2 to each scale-like bract of a cylindric or 

 ellipsoid erect spike ; bracteoles 2-4, united to the base of the bract. 

 Perianth 0. Ovary naked, sessile, compressed, 2-celledj styles 2, 

 cylindric, short. Ovules solitary in each cell, pendulous; micropyle 

 superior. Frtdting-spilces cone-like, ovoid or ellipsoid, with the 

 somewhat accrescent bracts and bracteoles woody and persisting 

 after the fall of the nutlets. Nutlets small, compressed, 2-winged 

 or wingless. Seed 1 by abortion ; cotyledons flat. 



