On The Origin of Species by Charles Darwin Chapter 3 Page 26

in the few spots where they do exist; and that of some social plants being social, that is abounding in individuals, even on the extreme verge of their range.

For in such cases, we may believe, that a plant could exist only where the conditions of its life were so favourable that many could exist together, and thus save the species from utter destruction. I should add that the good effects of intercrossing, and the ill effects of close interbreeding, no doubt come into play in many of these cases; but I will not here enlarge on this subject.

5. Complex Relations Of All Animals And Plants To Each Other In The Struggle For Existence

Many cases are on record showing how complex and unexpected are the checks and relations between organic beings, which have