40 NEW YORK STATE ^MUSEUM 



unharmed and the flowers appeared as usual at a distance, the 

 essential organs having been killed, no fruit developed. 



Cattle sometimes browse on the twigs of thorn bushes. In such 

 cases the injured branches put forth many new shoots which are 

 short and dense and form an almost impenetrable surface growth. 

 If the bush is low enough to be browsed from top to bottom it 

 gradually assumes a conic shape. If it is so tall that cattle can 

 not reach the ends of the upper branches these continue their 

 normal growth and the lower part of the bush assumes a conic 

 shape and the dense ramification. The whole bush then appears 

 somewhat like two cones with their vertices united, the lower 

 with its vertex pointing upward, the upper with its vertex point- 

 ing downward as in an hourglass. Tliis behavior of thorn bushes 

 under the pruning given them by browsing cattle indicates their 

 suitability for hedges. 



Herbarium specimens of species of this genus should be col- 

 lected at three different times. The first collection should be 

 made when the plant is in floAver. This collection will show the 

 characters of the flowers, of the young shoots and of the young 

 and unfolding leaves. The second should be made when the leaves 

 have become fully developed. This will show the character of the 

 mature leaves and of the young fruit. The leaves at this time are 

 in much better condition than late in the season when the fruit 

 is ripe. At this time it is also well to collect specimens of the 

 3'oung vigorous shoots, since the leaves on these are often larger 

 and differ more or less in shape from those on older and less vigor- 

 ous lateral or fertile branches. The third collection should be 

 made w^hen the fruit is ripe. Its object should be to get this in 

 as good condition as possible. Insect larvae and parasitic fungi 

 often injure and deform the fruit and it is well to select as far as 

 possible such specimens as are most free from these pests. Some- 

 times nearly every fruit on a shrub or tree is found to be injured 

 by them. In some species the fruit ripens very late. In such 

 cases the leaves are ready to fall or have already partly fallen 

 when the fruit is ripe. Specimens bearing ripe fruit should not 

 be severely pressed lest the fruit be crushed. It is well to dry 



