164 STUDY OF COMMON PLANTS. 



XXII. THE CROWFOOT FAMILY, 

 RANUNCULACEJE. 



MATERIAL REQUIRED. 



Specimens of the early crowfoot, Ranunculus fascicularis, Muhl., some 



in flower, others in fruit. 

 Similar specimens, as they can be obtained, of Anemone nemorosa, L., 



and Caltha palustris, L. 

 Representatives of other genera, such as Hepatica, Clematis, Aquilegia, 



Actsea, Hydrastis, etc. 



EARLY CROWFOOT. Rununculus fascicularis, Muhl. 

 Distribution. 



Record what you have observed as to the habitat of this 

 species. For the use of the term habitat cf. Gray, Struct- 

 ural Botany, p. 366. Do you regard it as indigenous or 

 introduced ? 



NOTE. This is often a difficult question to settle. We have to de- 

 pend partly on recorded observations and partly on what we now see of 

 the habits of the plant, the places where it grows, the direction in which 

 it spreads, and so on. Trustworthy evidence is attained when competent 

 botanists actually observe for a period of years and record the stations 

 occupied by the species in question. 



Observations of this kind are of much interest, and if properly con- 

 ducted may be made of great scientific value. Constant changes in the 

 vegetation of a given locality are taking place, due either to the introduc- 

 tion of foreign species or to the disappearance of indigenous plants, as 

 the result of changed climatic and other conditions. Some introduced 

 plants have so taken possession of territory invaded by them as to become 

 formidable rivals of the native species, and even to crowd them out. The 

 Canada thistle, prickly lettuce, butter-and-eggs, hound's tongue, and 



