224 



The p^ant belongs to the Leguminosae, and its leaves undergo the move- 

 ments for adjustment to the intense sunlight and to the cool night air 

 in the same general manner as the Guango, or the Shameweed. 



If an examination of the 

 compound leaf is made it 

 will be found to consist of 

 one large terminal leaflet, 

 and one or two small lateral 

 ones. (See Fig. 7.) 



The small lateral leaflets 

 keep up a rather rapid con- 

 tinuous jerking movement at 

 times when the tempe rature K gl b ^ant° f 

 is between 72 and 104° F. modium gyiahs.) 



(Des- 



The movement continues 

 even in the night and these 

 leaflets do not' undergo 

 " J-leep movements". The 

 tip of the leaflets move up- 

 ward and downward through 

 an arc of one hundred and 

 eighty degrees and at the 

 same time twists on the 

 "stalk so that an irregular 

 oval or ellipse is described. 



From two to five minutes are nece ssary to complete the movement. 



W e are not only unable to ascribe any useful purpose to this move- 

 ment of the Telegraph Plant but do not understand the mechanism by 

 which ir is produced. Such marked and continuous movements are by 

 no means common among the higher plants. 



It is necessary for 

 every green plant to lift 

 its leaves aloft into the 

 sunlight To accomplish 

 this more or less rigid 

 stems and branches are 

 constructed upon which 

 the leaves are displayed. 

 A comparatively enor- 

 mous amount of mate- 

 rial, energy and time are 

 used in this process, 

 and the plant which gets 

 up to the sunlight with- 

 out this expenditure will 

 have a great advantage 

 over other forms. One 

 group of plants, the air 

 plants (epiphytes) obtain 

 exposure to the light by 

 growing on the elevated 

 branches of other plants. 



A not h er g oup of par- 

 ticular interest in con- 

 nection with this discus- 

 sion, accomplish the 

 Fig. 8. Tendril of Granadilla (Passiflora quadrangu- same purpose by climb- 

 laris.) a. Normal position, b curved after irritation, ing upward over the 



bodies of other plants or any object near them. They may cling to the 

 support by twining round it, or by means of special grasping organs or 

 tendrils. The latter class is the most highly developed group since it 

 accomplishes the climbing at the least expense. 



