1892.] NATURAL SCIENCES OF PHILADELPHIA. 161 



been formed. In brief, the power to produce offshoots or stolons is 

 really the only difference between the annual or perennial herbaceous 

 plant. 



It may now be further noted that, morphologically, there is no 

 difference between a stolon and a flower scape, — a rhizome or a 

 permanent flower stem. The strawberry is one of the best illustra- 

 tions of this. The "Bush Alpine" never makes a "runner" — all 

 that would be stolons becoming erect flow'er scapes. The transitions 

 between flower scapes and stolons may be seen at any time by the 

 careful observer. But the flower scape is an annual, while the 

 stolons remain over until another season. 



We may now consider the causes inducing the annual or the 

 more enduring conditions. It is now^ well understood that though 

 the reproductive condition of a plant is a natural outgrowth of the 

 vegetative, there is a certain antagonism between them. The 

 husbandman must root — prune, or take off a ring of bark, or practise 

 some such severe measure, before an extra vigorous tree can l)e 

 made productive. On the other hand even sound trees have been 

 led to death's door by overbearing. Annuals die from no other 

 cause than by the heavy draft on vital power through bearing seed 

 so early and profusely, with nothing but a single root-stock to 

 provide nutrition for the whole. 



Professor Holm, though he is not clear whether it is climate, soil, 

 cultivation or other cause, which leads the annual occasionally into 

 the perennial class, quotes Lange as showing that Carex eyperoldes, 

 under normal conditions truly annual, is " able to vegetate several 

 years Avhen it happens to live without flowering." Several years ago 

 I had a number of plants of the caraway, Carinn C«rti/, transplanted 

 after they had commenced to push up flower stalks. As the flower 

 stalks withered, they were plucked out to the base. All the 

 plants became bushy perennials ! Pi'ofiting by the hint I have 

 some plants, with the stems annually plucked out, that are now four 

 years old. 



Going back to the strawberry, why does the scape die the same 

 season, and the stolons endure? Is it not that the stolons, sending 

 out roots at the end which form leaves instead of flowers, are under 

 more favorable conditions of nutrition? The scape is drawing 

 heavily on vitality Avhich the unfavorable conditions of nutrition 

 do little to sustain. 



