Polunin • Aspects of Arctic Botany 61 



of the latter nature, but probably others different factors are operative in dif- 



are not. ferent cases and that sometimes several 



Genetics and physiology lie very factors may act together. One of the 



close to ecology and in fact are apt to beliefs most widely held is that, follow- 



overlap. To a considerable extent ing the last glacial retreat, plants long 



ecolog)' and genetics are complemen- isolated came together in the North 



tar)', as an organism is what it is and and hybridized, and have continued 



does what it does largely because of this process ever since. Doubtless this 



the interaction of environment and has happened to some extent, though 



heredity— both fields are necessary for how widely and pertinently it is diffi- 



the continued existence of the organ- cult to gauge. Tlien again, the ecolog- 



ism, neither being more important than ical amplitude, the tolerance to a range 



the other. Even closer is the relation- of conditions, of many species is very 



ship between ecolog}' and physiology, wide in the Arctic, and this fact prac- 



both of which deal with functions, tically demands a morphological plas- 



though generally at different levels of ticity which might be expected to be 



organization. further emphasized by differing envi- 



This brings me to a further point, ronmental impress. Another possibility 

 more directly concerned with plant would seem to be that the rigorous arc- 

 geography. Study on a full circumpolar tic climate is conducive to the produc- 

 basis of the vascular plants known to tion of mutants and polyploids as well 

 reach the Arctic, and of some species as of various genetical or transient 

 throughout their range on earth, which "ecological" forms. Yet another possi- 

 I contend should be considered where- bility is that the low degree of biotic 

 ever possible, has convinced me that competition and the multiplicity of 

 many of the entities commonly upheld micro-habitats permit all sorts of bio- 

 as species should really be united. Fre- types to persist, 

 quently, these so-called species stand 



out as distinct races that possibly genetics and aerobiology 

 should have the rank of subspecies. 



These forms often hybridize freely Furthermore, there is another factor 

 where their ranges overlap, and also which may be contributing to the com- 

 show clines of gradual change from plexit)^ of some wind-pollinated plant- 

 area to area. But when sufficient ma- groups in the Arctic, namely, the dis- 

 terial is examined, the t}^es are seen persal of genes and subspecific charac- 

 to var}'— in many cases similarly or in ters over great distances by the wind, 

 parallel fashion even in different areas In this connection it should be recalled 

 involving different subspecies. In this that even a single pollen grain finding 

 connection, it is good to see the mod- its stigmatic billet in a millennium 

 ern tendency to "lump" together many might serve to establish a subspecies, 

 arctic types in the interest of scientific genetically speaking, in an entirely new 

 understanding and practicability. region. For it is now known that, under 



suitable conditions, a wide range of 



diversity factors pollen grains, as well as fungal spores, 



bacteria, etc., can remain viable for 



Now what is the reason for arctic months with almost unimpaired germi- 



plants being so notoriously plastic and nation and fertilization potentialities, 



difficult to treat taxonomically? Only During this time pollen grains could, 



a very bold man would hazard more like the dust of Krakatau, travel around 



than a guess, but it does seem that the world and more. I have become 



