KEY TO THE FAMILIES BASED MAINLY UPON FLOWERS. 



a Flowers unisexual, with ovules naked on tlie face of a scale ; leaves parallel-veined 

 (Oymnosperma'), mona?eions : ovules 2 or moi'e witli each scale; stamens numerous; fruit a 

 cone with imbricated scales or so modified as to resemlile a berry. 



Coniferse (p. 418). 

 a' Flowers with ovules inclosed in a cavity — ovary — {Aiifjiospcrmij;) and the parts of the 

 flower in 4s or 5s; cotyledons 2 (Dicotyledons) ; flowers 

 b Without a corolla (ApetaUe), 

 c Unisexual and 



d Calyx absent or irregular if present; flowers appearing 

 e After the leaves, the staminate 



f From axillary buds on growth of the previous season, in drooping aments ; 

 pistillate solitary or in few-flowered spikes terminating new shoots on the same tree; fruit a 



nut; leaves comijound, deciduous Juglandacese (p. 423). 



f- From the axils of evergreen simple leaves, in erect aments; fruit a wax-coated 



berry Myricacese ( p. 424 ) . 



t' Mostly from the axils of bud-scales at the base of new shoots and in 

 g Drooping 



h Long-peduncled heads ; the pistillate solitary or in pairs terminating shoots 



on the same tree Fagns, in Fagaceae (p. 429). 



h- Slender drooping aments; pistillate flowers from axils of leaves on the 



same shoots Quercus, in Fagacese (p. 430). 



g^ Ej-ect axillary aments ; the pistillate at the bases of the same aments. 



Castanea, in Fagaceae (p. 430). 

 f In heads arranged in terminal i-acemes. 



Liiquidambar, in Hamamelidaceae (p. 437). 

 e° Before or with the leaves 



f From axillary buds which are 



g Covered with one or more bud-scales 



h Both staminate and pistillate flowers in aments and on different trees. 



Salicacese (p. 425). 

 h^ Staminate only in aments; the ]jistillate in slender terminal spikes on 



same tree Carpinus, in Betulaceae. 



h° In panicles, dia-'cious, without petals; leaves compound; fruit a samara. 



Fraxinus, in Oleacese. 

 g- Naked — not covered with true bud-scales ; ovary superior ; fruit an elongated 



compressed drupe Leitneriacea; (p. 425) . 



t' Terminating shoots of the previous season and 



g The staminate (only) remaining naked during the previous winter; the 

 pistillate in spikes from lateral buds; staminate aments 



h Simple; fruit a strobile.. Betnla, in Betulaceae (p. 428). 

 h- Comiiound, 2-5 (usually 3) uiiifi'd at base; fmit resembling a hop. 



Ostrya, in Betulaceae (p. 428). 

 g' Both staminate and jiistillate remaining naked during previous winter, on 



.same hranclilets Alnus, in Betulaceae {-p. 429). 



d- Calyx ju'esent and legulai- ; flowers appearing aftei' the leaves; dicecious ; calyx 

 becoming enlarged and succulent in the com|iotind fruit. 



Moraceae (p. 433). 

 c' Perfect ; calyx present, i-egular; ovary suiicrior, 1-celled and usually 1-seeded ; flowers 

 in fascicles or racemes befoi'e oi- with the leaves; fruit a 

 d Samara, winged 



e Nearly or quite all around TJlmus, in Ulmaceae (p. 4.32). 



e^ Obliquel.N fi-om one end and arranged in ]jairs. 



Acer, in Aceraceae (p. 446). 



d' Drupe Lauraceae (p. 435 ) . 



h' With a corolla and that consisting of 

 c Separate petals (Pohjpetalm) 

 d Ovary superior 



e Flowers perfect and 

 f Regulai' 



g t'al.vx consisting of three sejails; stamens numerous; pistils 

 h Numerous, fi'oin an elongated lecejjtacle ; ovar,\' 2-ovuled. 



Magnoliaceae (p. 4'{4 ) . 

 f Few, from a globose receptacle ; ovary many-ovuled. 



Asimina, in Anonaceae (p. 43.5) 

 [ix] 



