DICOTYLEDONOUS PLANTS. 19 



A tall shrub or slender, straggling tree, 15-30 ft. high, seldom 

 growing erect, often several trunks springing from the ground 

 almost in contact and slanting away from each other. 



c. (B. nigra). River or Red Birch. Leaves ovate diamond- 

 shaped, acute at both ends, twice serrate. Twigs very slender and 

 drooping (Fig. 28), brownish or cinnamon-brown when young. Bark 

 of the larger limbs and trunk loose, shaggy, reddish-brown. A tree 

 30 to 50 ft. high. 



II. CORYLUS, HAZELNUT. 



Staminate flowers in slender drooping catkins, each flower 

 consisting of 8 stamens with 1-celled anthers. Pistillate 

 flowers several, grouped in a scaly bud, each consisting of a 

 single ovary in the axil of a bract and with a smaller bract at 

 each side; ovary somewhat 2-celled with 2 ovules, only one 

 of which matures ; stigmas 2, long and slender ; nut round- 

 ish, hard-shelled, enclosed in a more or less fringed cup. 

 Shrubs or small trees. 



a. (C. Americana), Hazelnut. Leaves roundish heart-shaped ; 

 stipules acute, from a broad base ; involucre open, showing the nut. 



b. (C. rostrata), Beaked Hazelnut. Leaves little, if at all, 

 heart-shaped ; stipules linear-lanceolate ; involucre completely cover- 

 ing the nut and prolonged into a beak beyond it. (The latter 

 species is not nearly as widely distributed as the former ; they can- 

 not be readily distinguished from each other until the fruit is 

 somewhat mature.) 



POLYGOWACEiE, BUCKWHEAT FAMH^Y. 



Herbs with alternate, entire leaves and usually with 

 sheathing stipules above the swollen joints of the stem. 

 The apetalous flowers are generally perfect, with a 3-6-cleft 

 calyx, generally colored and persistent. Fruit a compressed 

 or 3-angled akene, enclosed in the calyx. Seeds with endo- 

 sperm, which does not generally enclose the embryo. Stamens 

 4-12, on the base of the calyx. 



I. RUMEX, DOCK, SOREEL. 



Calyx of 6 nearly distinct sepals, the three inner somewhat 

 colored and in fruit enclosing the akene, 1 or more of them 



