428 BICKNELL: FERNS AND 
troduced fern, the common polypody, this having somehow found 
lodgment on the island at a single station. 
Among the introduced plants yellow flowers and white flowers 
greatly predominate, their ratios to the total number being re- 
spectively over 31 per cent and 28 per cent. White flowers and 
yellow flowers likewise predominate in the indigenous flora, but 
here white-flowered plants are relatively, as absolutely, much more 
numerous, their corresponding ratio being 39 per cent, that of the 
yellow-flowered 22 per cent. Next in order among the introduced 
plants come pink-flowered species, including purple-pinks, 19 per 
cent; purple and blue-purple, 12 per cent; blue, over 6 per cent. 
Orange and red are each found in only four species, and green- 
petaled flowers are no less rare. Eliminating those introduced 
species that seem to have little chance of permanency the resulting 
percentages show not much change beyond about 4 per cent de- 
crease in the purple- and blue-flowered species and a corresponding 
increase in the white-flowered. 
As among the introduced plants, so in the native flora flowers 
of some shade of pink, including those scarcely assignable shades 
lying between pink and purple, are next most numerous after 
whites and yellows, making up’nearly 17 per cent of the whole 
Purple and blue-purple follow with over 8 per cent; blue with 
nearly 4 per cent; red and orange, the one something over, the 
other a little under 1 per cent. A wide percentage disparity is 
found between the native and the introduced plants that bear 
flowers fairly to be described as green, these numbering less than 
I per cent of the introduced species and over 8 per cent of those 
of the native flora. 
From the nature of the case all these percentages are somewhat 
approximate, not being susceptible of very exact rendering. 
Petalous flowers only have been taken into the reckoning. 
* * * * 
The indigenous flora of Nantucket has its most interesting 
side to the botanist in its many species of plants that more es- 
pecially abound southward on the coastal plain. This is its domi- 
nating note. But mixing with these plants of southward range are 
others which trace through the flora a strain of northward re- 
lationship that is all the more sharply defined by the emphasis 
of contrast. 
