BetulaceaCy Fagaceae 35 



opposite the tepals. Carpels (2-6). Ovary sub-inferior, 

 usually more or less completely 2-3-locular (after fer- 

 tilisation) with 1-2 pendulous, anatropous, parietal 

 ovules in each loculus. Fruit usually a nut. Endo- 

 sperm o. 



Fam. I. Betulaceae. Flowers usually appearing 

 before leaves. Perianth present in flowers of only one 

 sex. / catkins compound. ^ flowers united to their 

 bracts. Stamens 2-10. Filaments often dividing into 

 two, each branch bearing a half-anther. % catkins often 

 minute. Carpels (2). Styles 2. 



Tribe i. Coryleae. ^ flowers without perianth. 

 % flowers with perianth. Fruit not winged, enclosed 

 in the enlarged, herbaceous bracts. 



Leaves in bud folded parallel to lateral nerves. 

 % spike large. Fruiting bracts open 3-lobed. Carpinus. 



Leaves in bud folded parallel to midrib. % spike 

 minute. Fruiting bracts forming a cupule. Corylus. 



Tribe 2. Betuleae. J flowers in dichasia, with 

 perianth. % flowers without perianth. Fruit usually 

 winged. 



Filaments branched. $ catkins falling at end of 

 the first summer. Betula. 



Filaments simple. Empty % catkins persistent for 

 more than one year. Alnus. 



Fam. 2. Fagaceae. Flowers and leaves appearing 

 together, or flowers appearing after leaves. Flowers of 

 both sexes with perianth of 4-7 connate tepals. ^ catkins 

 simple or compound. Stamens 4-14. ? flowers in 

 3-2-flowered dichasia or solitary. Carpels usually 3-4. 

 Styles 3-4. Fruit surrounded b)^ involucre {^cupule). 



3-2 



