270 Transactions.— Botany. 
period through the agency of man, direct or indirect, or whether it is that 
in addition to possessing great flexibility of character and consequent power 
of adapting themselves to varied conditions, they have also been able to 
spread widely by natural means of migration, it is now for the most part 
impossible to say— probably both causes have operated. Their wide ranges, 
however, make it difficult to state their distribution with exactness, but the 
following will be found to be a sufficiently close approximation. 280 are 
natives of Europe, many of them also ranging into temperate Asia and 
North America, and some into -North Africa, but for our purpose it is not 
important to specify these. 10 species, not European, are from the eastern 
portion of North America, and 4 are from the western side of the same 
continent. This will make a total of 294 species introduced from the north 
temperate zone. From Australia, notwithstanding its nearness to us, we 
have only received 10; from Chili and the cool portions of South America, 
9; from the Cape of Good Hope, 21. The number naturalized from the 
south temperate zone is thus only 40. Finally, there are 58 species from 
the subtropical and tropical portions of both hemispheres, most having a 
very wide distribution. 
With respect to the habit and duration of the species, only 31 are trees 
or shrubs, the remaining 856 being herbaceous. Of this latter number 176 — 
are annual, 28 biennial, 152 perennial. The large proportion of annual 
species is noteworthy, as in the indigenous flora nearly all the herbaceous 
plants are of perennial growth. 
If it is endeavoured to divide the species into groups according to the 
nature of their habitats, it will be found that nearly two-thirds fall, in about 
equal numbers, into three classes: first, weeds of cultivated lands and 
gardens; second, inhabitants of meadows or fields; third, plants of road- 
sides or waste places. Of the remaining third a considerable proportion 
are escapes from gardens, or other plants whose position it is difficult to 
define at present, and which occupy very various stations : littoral, paludal, 
sylvestral, etc. 
Finally, we find that the species belong to 283 genera, arranged in 60 
orders. The orders best represented are,—Graminee, with 60 species, 
Composite 51, Leguminose 85, Cruciferae 20, Caryophyllee 15, Rosaceae 14. 
Of the genera no less than 182 are without indigenous representatives 
in this country, and 16 of the orders are in the same position. The large 
number of genera into which the species are distributed shows that our 
naturalized flora is of a very diversified character; and the fact that most 
of the genera have no indigenous species, proves that naturalized plants, to 
succeed in any country, need not have any close affinity with the pre-exist- 
ing inhabitants, 
