1903.] NATURAL SCIENCES OF PHILADELPHIA. 663 



V. fimbriatula and its forms, the most pubescent species of the genus, 

 are always found on exposed dry sandy or rocky banks, but V. villosa 

 and V. palmata, also pubescent, are woodland species, and grow closely 

 associated with V. afjUnis, which is glabrous. It may be said, how- 

 ever, that all species of moist, open ground are essentially glabrous, 

 viz., V. cucullaia, V. crenulata and typical V. sagittata. 



The relative length of petioles and scapes is often quoted as, a distinct- 

 ive character, but such comparison should explicitly be made with 

 either the first or second set of leaves, as the "flowering period" often 

 covers the growth of the second leaves, so that early flowers are longer 

 than the leaves while later ones are shorter. The length and character 

 of the peduncle of the later cleistogamic flowers is an important 

 specific character, as first pointed out by Prof. Greene. In some spe- 

 cies it is long and erect, notablj'' in V. cucullata; in others horizontal, 

 and in others still A^ery short and decurved and usually hypog?eous. 

 Except that in all wet-meadow species the cleistogenes are erect, we 

 can make no correlation between their condition and the nature of 

 their habitat, for in some forms that do not grow in wet spots, as V. 

 emarginata, they are equally erect, while in other dry-ground species 

 they vary much in length. 



In floral characters violets seem to present a great amount of indi- 

 vidual variation, but the difficulty of preserving the blossoms makes 

 satisfactory comparisons on a large scale practically impossible. 

 While a certain tint of blue or purple is characteristic of each form, 

 there is also a good deal of individual variation. The marsh forms of 

 the V. cucullata group are all pale blue, but the only colony of V. 

 emarginata that I have studied in flower were almost as pale, though 

 the species grows in dry, sandy situations. On the other hand, V. 

 sagittata, from wet meadows, has as dark purple flowers as we find in 

 V. villosa of the dry woodlands, so that in color also we find little 

 correspondence with immediate environment. 



The extent of pubescence on the petals is an important specific char- 

 acter, and varies from V. septemloba, where it is confined to the bases 

 of the lateral petals, to V. sagittata, in which it usually spreads to 

 some extent over all, though sometimes absent from the two upper- 

 most. 



As to relative time of flowering in the vicinity of Philadelphia, V. 

 fimbriatula, villosa and afflnis are the earliest, and are about over when 

 cucullata, and dilatata come into bloom, the difference being about two 

 weeks; the other acaulescent blue species begin to blossom about 

 midway between these two groups. 



