TYPES AND KINDS OF STEMS 4! 



hold tightly to it. The tendrils of the American jvy (Ampelopsis 

 quinquefolia) behave in a similar way. Twining, or coiling 

 climbers, coil around the object of support, as the hop, morning 

 glory, climbing bean. All twining stems do not coil around the 

 object of support in the same direction, but a given species always 

 coils in the same direction. The morning glory coils from right 

 to left, i.e., against the sun, while the hop coils in the opposite 

 direction, i.e., with the sun. In the tropical forests climbing 

 stems reach their greatest development. Some of the lianas (as 

 these climbing plants are called) have stems the diameter of large 

 trees. One curious one (Copernicia tectorum) forms a network of 

 anastomosing branches around palms. 



Fig. 42. 

 Stolon, or runner, of strawberry. 



68. Prostrate stems. Prostrate stems trail or " creep " on the 

 ground. The dewberry and strawberry are examples of climb- 

 ing land plants. These are also called stolons from the habit of 

 creeping on the ground for a distance, then striking root and 

 developing a cluster of leaves, while the main stem continues as 

 a creeper and strikes root again, and so on. The water fern 

 (Marsilia) is a good example of a prostrate aquatic plant. 



69. Root stocks, burrowing stems, or rhizomes. These 

 are subterranean stems. They may be long and extend for a 

 considerable distance in the ground as in the mandrake, false 

 Solomon's seal, many grasses, the bracken fern and sensitive fern; 

 or the stem may be short and thick like the underground stem of 

 the wake robin (Trillium). Such underground stems are called 

 root-stocks. Most of them, as in the case of the mandrake, false 

 Solomon's seal, wake robin and grasses, have erect stems which 

 arise as branches from the root-stock and bear the flowers and 



