6 Addisonia 



states and on the Pacific slope. They are in their greatest abun- 

 dance, not only as to kinds but also as to individuals, in the lime- 

 stone formations of the St. Lawrence and Great Lakes regions, and 

 in those of the Missouri-Arkansas region, but few growing near the 

 Atlantic coast. 



Up to the end of the nineteenth century there were less than a 

 hundred species of thorns known. With the advent of the twen- 

 tieth century, however, there was great activity in the study of 

 these plants, an activity so great that in the first decade about one 

 thousand North American species were proposed, many of them 

 based upon such trivial and variable characters that it is impossible 

 to maintain them. When a rational treatment of this genus makes 

 its appearance the list of synonyms must of necessity be extremely 

 large, adding greatly to the confusion already existing in this diflS- 

 cult group. 



The thorns are well adapted for hedges, borders, and screens, 

 their rigid thorn-beset branches making an excellent barrier against 

 both animal and man, and their showy flowers and handsome fruits 

 giving them great decorative value. When in flower they are cov- 

 ered with a mantle of white bloom, providing, if care be taken in 

 selecting species of different flowering periods, a mass of flowers from 

 the middle of May to the middle of June. Some of the forms ripen 

 their fruit late in August or early September, while others mature 

 theirs much later, giving the thorns a wide range of decorative 

 possibilities. The fruit is of recognized economic importance in 

 some localities, being used in the preparation of preserves and jel- 

 lies. When the wonderful development of the common apple is 

 considered, the possibilities of improvement in the thorns are prom- 

 ising. 



Propagation is effected commonly by seeds, but hybrid forms and 

 those with double flowers may be propagated by grafting. The 

 seeds of some species germinate the first year, while in others two 

 years are required. 



George V. Nash. 



Expi,ANATiON OP Plate. Fig. 1. — Fruiting branch. Fig. 2. — Flowering 

 branch. 



