R^LC ( Riitacece) 47 



Kalm's St.-John's-wort. H. Kalmianum, L. 

 Flowers, one inch across, three to seven in a close cluster. 



Styles, five. Seed-case, five-celled. 

 Leaves, one to two inches long, crowded and narrow. 



Branches, somewhat four-sided, with two of the edges 

 slightly winged. 



Fruit, egg-shape. 



Found, on wet rocks at Niagara Falls, and among the 

 northern lakes. 



7. Family RUTACE^. (Rue Fam.) 



Flowers, small, greenish-white, in clusters ; sometimes taking the stam- 

 inate and the pistillate forms on different shrubs. Petals, three to 

 five, not united. Sepals, three to five, or wanting. Stamens, in 

 the staminate flowers, as many as the petals and alternate with 

 them ; in the pistillate flowers, either imperfect or wanting. Seed- 

 cases, one to five, free from the calyx. 



Leaves, compound, alternate, dotted when held to the light ; edge of 

 leaflets entire or nearly so. Stipules, none. 



Bark, pungent or bitter. 



Fruit, one- to two-seeded, one-celled, splitting into two pieces, thick 

 and fleshy, a fleshy pod ; or two-celled, two-seeded, thin, and 

 winged all around ; a samara. 



GUIDE TO THE GENERA. 



Stems prickly ; Seed-cases three to five, separate. (i) Xanthoxylum (Prickly Ash). 

 Stems not prickly ; Seed-case, one with two cells. (2) Ptelea (Shrubby Trefoil). 



(i) Genus XANTHOXYLUM, L. (Prickly Ash.) 



From two Greek words meaning "yellow " and " wood." 



Fig. 8. Northern Prickly Ash. Toothache Tree. 



X. Americanum, Mill. 



Flowers, in small, dense clusters at the sides of the 

 branches, appearing before the leaves, and sometimes 

 taking the pistillate form on one tree, and the stam- 

 inate on another. Petals, four to five. Sepals, four 



