46 THE AMERICAN BOTANIST. 
ance and profuse blossoming of every hue from deep rose 
to white. In the brillianc}' of its coloring the cardinal 
flower is unsurpassed b^- any other red flower. 
The purple flowers number 422. This group contains 
both red-purple and blue-purple flowers, as well as a few 
•brown, green and ^^ellow-purple flowers. It presents 
evidently a much greater variety of hues than any one of 
the preceeding groups. Red-purple flowers are common in 
the orchid and geranium families, while blue-purple are 
numerous in the pea and mint families. The flowers of 
Aristolochia, or Ijirthroot, are lurid purple. In the Dutch- 
man's pipe of cultivation (.4. sipho) the calyx is prolonged 
into a tube, with a contracted throat either straight or 
shaped like the letter S, which is set on the inside with 
reflexed hairs. Flies can creep inside easih^, but the hairs 
prevent their escape. As soon as the anthers have 
ripened, the hairs wither and the imprisoned insects, now 
more or less covered wnth pollen, are set free. These 
flow^ers should be compared with the pither-like leaves of 
Sarracenia and the spathes of Arum, as all three serve as 
traps for small flies and are lurid purple, a color which is 
thought by some to be attractive to these insects. 
The 325 northern blue flowers are most common in 
the pea, violet, gentian, mint and figwort families. They 
are often very irregular in form, with the honey deeply 
concealed and accessible only to the long-tongued bees. 
There are quite a number of flowers which are adapted to 
bumblebees alone. The range of the aconites (Aconitum)^ 
which are pollinated by bumblebees, is determined by the 
geographical distribution of this genus of bees. In the 
Alps the gentians are very numerous and display vivid 
masses of blue coloring. Huxle3^, while seeking health in 
the bracing air of these mountains, found great delight in 
the study oi these plants. Blue flowers are derived 
frequently from red, yellow or white progenitors. Some- 
times this color variation ma3' be observed in individual 
flowers, as in Myosotis versicolor, which is at first ^^ellow 
but later changes to blue. 
