MEMOIRS PROM THE DEPARTMENT OF BOTANY OF COLUMBIA UNIVERSITY 37 



Stems much elongated, 5-10 dm. long, with more appressed pubescence; leaves 

 larger, with leaflets often 5-6 cm. long, more glabrate and green. 



Well developed forms of this variety are very unlike the typical P. Canadensis, and 

 Mr. Bicknell and Mr. Nash believe that it may be a good species. I have been unable, 

 however, to observe any definite character by which to separate the two. As there seem 

 to be several intermediate forms, I leave it at present as a variety ; when the plant is 

 better studied in the field it may be possible to separate from P. Canadensis not only P. 

 simplex but perhaps one or two other species. 



The variety has about the same range as the species, but seems to be more common, 

 especially westward. 



8. Potentilla pumila Poir. 



Potentilla pumila Poir. in Lam. Enc. Meth. 5 : 594, 180i ; Nutt. Gen. N. A. PI. 1 : 

 310 ; Persoon, Syn. PL 2 : 55 ; Sprengel, Syst. Veg. 2 : 537 ; Eat. Man. Ed. 2 : 379. 



Potentilla Canadensis pumila Torr. tt Gray, Fl. N. Am. 1 : 443. 1840. 



Lehm. Rev. Pot. 187 ; Gray, Man. Ed. 1 : 122; Ed. 2 : 118; Wood, Class Book, 343j 

 Walp. Ann. 2 : 513 ; Rydb. Bull. Torr. Bot. Club, 24 : 10. 



Illustration : Britton & Brown, 111. Fl. 3 : /. 1935a. Plate 18, f. 1 ; dissection 

 of flower,/. 2. 



Perennial, low, less than 1 dm. high. Stems at flowering time very short and up- 

 right ; later on producing longer runner-like and prostrate branches, densely silky-stri- 

 gose. Stipules small, lanceolate, entire or toothed. Basal leaves with silky-strigose 

 petioles 2-4 cm. long, densely silky strigose, digitately 5-foliolate ; leaflets obovate, 

 about 2 cm. long, coarsely serrate. Flowers few, axillary, the first one generally from the 

 axil of the first stem leaf with a slender strigose pedicel 3-5 cm. long, 6-10 mm. in 

 diameter. Hypanthium densely silky-strigose ; bractlets and sepals subequal, narrowly 

 lanceolate. Petals yellow, obcordate, a little exceeding the sepals. Stamens about 20. 

 Styles slender, filiform. 



This is nearly related to P. Canadensis, but Messrs. Bicl^nell and Nash, who have 

 studied the plant in life are fully persuaded that it is distinct. Specimens of P. 

 Canadensis and P. pumila are planted side by side in the New York Botanical Garden 

 and retain their characters perfectly. It is therefore best to regard P. -pumila as a dis- 

 tinct species, especially as it is confined to the Atlantic States, while P. Canadensis is 

 also common in the Mississippi Valley- A few of the specimens studied are the follow- 

 ing: 



New York: Ehzabeth G. Knight, 1877 ; Torrey; N. L. Britton, 1891. 



Pennsylvania: J. K. Small, 1889, 1890. 



