406 CLIMBING PLANTS. 
quite full, as it is likely the original paper has been read 
by but few readers of the NATURALIST. 
Climbing plants may be divided into those which spirally 
twine round a support ; those which ascend by the movement 
of, the foot-stalks or tips of their leaves; those which ascend 
by true tendrils; those which are furnished with hooks, and 
those which are furnished with rootlets. The last two ex- 
hibit no special movements and are of less interest than the 
first three. 
Spirally Twining Plants. —I begin with a special case, 
one depending upon my own observation, similar to the one 
taken by Mr. Darwin. A thrifty hop-vine in my yard went 
up nine or ten feet to the top of a stake. Still aspiring it 
ran above the support, at the same time reaching off and 
swinging round and round following the course of the sun. 
When about two feet above the stake the tip of the vine cir- 
eumscribed a circle two feet in diameter. While it grew 
longer the extent of the circle was about the same, as a 
part of the vine had become strong and remained nearly 
stationary. By observations made at different times in the 
ay it was found to perform one revolution in from one to 
two hours, moving most rapidly in the warmest part of the 
warmest days. It is now four feet and two inches above any 
artificial support, and has just tipped over to the north-east 
in the direction of the prevailing wind. The revolving 
movement lasts as long as the plant continues to grow, 
but each separate joint or internode, as it grows old, ceases 
to move. In the ease of the hop and most other twining 
plants, about three internodes at a time partake of the 
motion. : 
The Hoya carnosa (Asclepiadacew) revolves opposite to 
the sun in five or six hours, making a circle of over five feet 
in diameter. The tip traced thirty-two inches per hour. 
It was an interesting spectacle to watch the long shoot 
sweeping night and day this grand circle in search of some 
object round which to twine. Sometimes it described nar- 
