166 MEMOIRS FROM THE DEPARTMENT OF BOTANY OF COLUMBIA UNIVERSITY 
The species of the genus Fragaria are very closely related to each other, and it is very 
often difficult to distinguish them from each other. The number that has generally been 
recognized for the United States is four, and for Mexico one, but the number is, how- 
ever, without doubt much larger. Until lately only two species were supposed to 
erow in the Atlantie States, and four in the Pacific States. The so-called vesca and Vir- 
giniana of the two regions are so unlike that it is impossible that they can be the same 
species, and the true /. vesca L. is not a native of America. The Hragarias of the Rocky 
Mountain region have been in such confusion that the names they bear on herbarium 
labels are hardly ever correct. ‘The trouble has been that altogether too small a num- 
ber of species has been recognized. The only reasonable treatment of the genus is to 
acknowledge about 20 species in North America, for should a smaller number be rec- 
ognized the question would arise as to how to dispose of the numerous intermediate forms. 
I have endeavored to arrange the species in natural groups in somewhat the same way 
as the arrangement adopted in Potentilla and Horkelia, but all these attempts were in vain 
on account of the close relationship of the members of the proposed groups. The general 
arrangement that is found in manuals and monographs consists in dividing the genus 
into two series, one with superficial achenes, the other with the achenes set into pits. 
This will not do for the North American plants, for in some species, as for instance in 
F. Chiloensisand F. Californica, the pits are very shallow. The latter, although with evi- 
dent pits, is a rather close relative of the European /. vesca and F. collina, both of which 
have superficial achenes. 
The pubescence of the scape and petioles has been used to distinguish related species, 
even between groups. In some species the pubescence on these parts is appressed or 
slightly spreading, in others it is spreading nearly at right angles to the stalk or even 
somewhat reflexed. Although this is not a reliable character in all cases, it has been 
employed by me in this work in the key to the species, as it is in most cases a very 
convenient one; it must, however, be remembered that the key is artificial, and too much 
stress should not be laid upon it. The general description will give a better and more 
reliable definition than the key affords. 
Fragaria Chiloensis, F. grandiflora, and FE. Carolinensis' constitute a very natural group 
with very large flowers and thick and rather coriaceous leaves which are strongly veined 
and are more or less puberulent under the long silky hairs on the lower surface. /. ewneifo- 
lia Nutt., however, agrees perfectly with this group, except in being of a much smaller size 
and having very small flowers. J. crinita (F. Chiloensis var. Scoulert Wats., in part) has 
1 This is not, as may be supposed, a native of Carolina. Its origin is entirely obscure. It may be a hybrid between 
either of the other two species and F. Virginiana, or simply a garden form perhaps derived from F’. Chiloensis. 
