Dicotyls or Exogenous Plants. 31 



Sa'-jix lon-gi-fo'-li-a Muhl. Long-leaved Willow. Leaves linear- 

 lanceolate 'l-\ in. long, tapering to each end, nearly sessile ; Catkins 

 linear cyndrical ; shrub, along streams. 



|b. Leaves sharply serrate, finely denliciilalrd or snbeittire.' 



Sa'-llx cor-da'-ta Muhl. Heart-leaved Willow. — Leaves oblong-lance- 

 olate or narrower, green both sides or scarceh- paler beneath ; stipules 

 usually large and conspicuous; catkins rather slender. 



A. Catkins in earliest spring before the leaves. 



Sa'-lix dis'-col-or Muhl. Glaucous Willow. — Catkins closely sessile, 

 thick, oblong-cylindrical; leaves oljovate or elliptic-lanceolate; ir- 

 regularly crenate-serrate, bright green above, glaucous beneath. 



XIIL Order BET-U-LA'-CE-/E. BIRCH FAMILY. — Trees or shrubs; 



flowers in catkins, or the fertile sometimes in a head or very short 

 catkins; involucre to the nut none, or foliaceous or sac-like. 



Fertile flowers with a foliaceous involucre or bladdery bag a). 



Fertile flowers with no calyx and no involucre b). 



a. Nut small, subtended by an elongated leafy bractlet Carpinus. 1 



a. Nut small included in a bladdery or enclosed bag' Ostrya. 2 



a. Nut large, with a leafy coriaceous involucre Corylus. 3 



b. Fertile scales thin, 3-lobed, deciduous, stamens 2 Betula. 4 



b. Fertile scales thick, entire, persistent, stamens 4 Alnus. 5 



1. CAR-PI'-NUS. — Trees (or tall shrubs) with smooth, close gray 

 bark, the involucre-like bractlet open, enlarged and foliacious. 



Car-pi'-nus car-o-li-ni-a'-na Walt." Blue or Water Beech: Hornbeam; 

 Iron-wood. — Leaves ovate or oblong, sharply doubly-serrate, soon 

 nearly smooth. 



2. Genus OS'-TRY-A. — Tree with brownish furrowed bark; bract- 

 lets tubular, becoming a closed bladdery bag very much larger than 

 the small nut. 



Os'-try-a vir-gin'-i-ca (Mill.) Willd. Hop-Hornbeam; Leverwood ; Iron- 

 wood. — Leaves oblong-ovate, sharply doubly-serrate, downy beneath. 



3. Genus COR'-Y-LUS. — Shrubs or small trees; leaves thinnish, 

 doubly-toothed, fertile flowers, several in a scaly bud. 



Cor'-y-lus a-mer-i-ca'-na Walt. Wild Hazel-nut. — Leaves roundish 

 cordate; involucre open above and foliaceous, below^ coriaceous and 

 downy. 



