158 HARSHBERGER: PHYTO-GEOGRAPHIC SKETCH 
Trifolium hybridum, Lepidium Virginicum, Ambrosia artemistacfolia, 
Bidens connata, Panicum capillare, Amaranthus graecizans, Soli- 
dago (several species), Aster (several species), Populus alba, Helt- 
anthus annuus, Citrullus vulgaris, Onagra biennis. 
The list of weeds that grow in waste places near Philadelphia 
and other large manufacturing towns of our region is not exhausted 
with the above enumeration. Only the commonest plants have 
been mentioned. In general, it may be said that the plants of the 
ruderal formation are coarse, tall, much-branched weeds of an ill 
smell and producing an abundance of easily distributed fruits and 
seeds. These weeds owe their presence in such abundance to the 
perfect means of distribution which they possess, as hooks, wings, 
tufts of hair, or other contrivances. 
BALLAST-PLANT FORMATION. — Ballast-ground may be defined 
as a place where the material used to steady ships at sea, such as 
sand, gravel, stone, rubble and the like, is unloaded from vessels 
and piled up in heaps along the water’s edge. The material com- 
posing ballast has been gathered from a great number of sources 
in a great many parts of the world, South America, Australia, 
Europe and India, from whence the ships have cleared. The re- 
sult is that roots, stems, fruits and seeds of a heterogeneous assem- 
blage of plants are mixed up in the ballast stuff, and when this 
lies exposed for some time the roots begin to grow and the seeds 
to germinate, until the ballast heap is covered by plants native to 
diverse parts of the globe. Some of these plants will appear but 
once. Others will remain and become adventitious. 
B. CULTIVATED. 
Southeastern Pennsylvania is preéminently an agricultural 
country. It is a country of well-kept, carefully cultivated farms. 
Now, however, many of the finest farms have been converted into 
suburban demesnes, where, dictated by the wealth and culture of 
the owners, large sums have been expended upon buildings and 
landscape improvements. For convenience and because the clas- 
sification is a natural one the cultivated plant formation may be 
divided into the following areas : 
1. Cereal-rootcrop-clover area. 
2. Orchard area. 
i i a i a ental 
