1888.] NATURAL SCIENCES OF PHILADELPHIA, 395 



I have collected this plant in its various forms over widely sepa- 

 rated portions of the American continent, — Canada, the Alleghanies, 

 California and Alaska, — and though holding its own wherever 

 found, it does not show evidences of the extension that must have 

 characterized it in the past, when, with no remarkably special- 

 ized organs favoring distribution, it managed to travel in its various 

 forms — as T. JEuropcea, T. Americana and T. Arctica — over the whole 

 north of Europe and across the American continent to Behring's 

 Straits. So far as I have seen in the localities named, the plants 

 seem to produce seeds, though not abundantly ; but there are no 

 evidences of seedlings. In the Chestnut Hill location, the only tract 

 on which the plant is found is but a few hundred square feet, yet 

 though unnoted, it must have been confined to this limited area foj- 

 at least a hundred yeai's, or perhaps for many centuries. The piece 

 of wood is a favorite botanical hunting ground. I myself have 

 wandered through it for over a quarter of a century, and the early 

 Philadelphia botanists — sharp-eyed as they were — would surely have 

 seen it here if at all common in those times. It is worth while 

 considering how so great a wanderer in remote ages should 

 have acquired such remarkable stay-at-home habits in recent times. 

 Some conditions favorable to distribution must surely have existed, 

 which have disappeared in modern ages. What can these changes 

 be? 



So far as persistency is concerned I note a fact, not recorded any- 

 where, that the plant is stoloniferous, bearing a small tuber at the 

 end of a slender thread, which reproduces the plant next year, the 

 whole of the previous years' plants, except these little tubers, dying 

 away. In this way the plant, through its progeny, can be a traveler 

 at the rate of two or three inches a year. It is remarkable that this 

 character is not noted by systematic authors, for the specimens in the 

 herbarium of the Academy taken at various times during the flowering 

 period, from difierent parts of the world, exhibit traces of the little tu- 

 bers at the ends of stolons that have evidently been passed over tor 

 true roots. It is hardly to be supposed that the plants have wan- 

 dered wholly by the aid of these little tubers, valuable as they 

 must be for persistency when once a foot-hold has been obtained. 

 We are forced to the conclusion that at some former period it re- 

 ceived much more aid from seed and seedlings than it receives in^ 

 modern times. 



