ern hemisphere. In examining the dis- Another fact, which might indicate that 



tribution of other groups in the southern the Dicotyledons have taken possession of 



hemisphere, it is found that Australia and comparatively unoccupied regions only, 



its general vicinity is prolific in peculiar is that they are very poorly represented, 



forms. In the case of the Monocotyle- so far as higher groups are concerned, in 



dons, however, the Australasian region is aquatic conditions. It would seem as 



the most poverty-stricken one in all the though the conditions of life in the water 



southern hemisphere. Just why the had been fairly well taken up by other 



southern hemisphere in general, and the groups. In looking over the display of 



Australasian region in particular, are un- Dicotyledons in the tropics of the eastern 



favorable for Monocotyledons, it is hard and western hemispheres, it becomes evi- 



to say. Of course in these cases the world- dent that there is no such difference be- 



families already mentioned are repre- tween the forms of the two regions as in 



sented. the groups previously mentioned. It will 



The other great division of Angio- be remembered, however, that in the case 

 sperms is known as Dicotyledons, which of the Cycads and palms, which were used 

 include such forms as our common for- as illustrations, they are restricted to 

 est trees, buttercups, roses, peas, mints, the tropics, and their eastern and west- 

 sunflowers, etc. As there are about eighty ern forms are separated from one anoth- 

 thousand of these Dicotyledons, it is im- er, not merely by oceans, but by temper- 

 possible to state anything very definite in ate and boreal lands. In the case of Di- 

 reference to the distribution of the group cotyledons this is different, for while they 

 as a whole. Taking the higher forms, are found in the tropics, they are found in 

 however, as representing the general ten- the other regions as well, and have better 

 dency of the group, some of the facts of chances for intermingling than the other 

 distribution are as follows : groups. 



It has been noticed that the Monocoty- This tropical display of Dicotyledons 



ledons are massed in the tropics, and that further shows the great prominence of 



the temperate and boreal regions have America in the display of forms. This 



been left comparatively free by previous appears not merely in the greater num- 



groups, with the exception of the Coni- ber of peculiar forms and often families 



fers, which only develop tree types. With which appear in tropical America ; but 



the coming of the Dicotyledons, there- whenever the continents are paired in the 



fore, the vast temperate and boreal re- display of forms, America is always one 



gions presented a particularly favorable of the pair, Asia or Africa being the other 



field, which they have entered and taken member. 



possession of. This vast group is promi- It will be recognized from what has 



nently adapted to living in the unoccu- been said that the whole subject of geo- 



pied temperate and boreal regions. This graphic distribution is a very extensive 



does not mean that they are not found in one, and that it will be a long time before 



the tropics for they hold their own there the important facts are recorded. The . 



with the other groups. importance of the subject rests not so 



Dicotyledons, however, succeeded in much upon the mere presence of certain 



working out but three world-families : plants in certain regions, but it has to do 



Composites, to which the sunflowers, with explaining just why the conditions 



dandelions, etc., belong; the Mints ; and are suited to the plants, and also just how 



the Plantains. There are other large the plants have come to be what they are 



families which characterize certain great and where they are. 

 areas, but they are not world-wide in John Merle Coulter, 



their distribution. 



44 



