ASEXUAL REPRODUCTION 299 



of their success in colonization to their capacity for 

 vegetative reproduction by buds arising from their 

 underground stems. 



To what are commonly called " runners " — that is, 

 prostrate shoots given off by a plant, which lie on the 

 ground and root — the name " stolons " (Lat. stolo, a 

 twig) has been given. Stolons give rise to new plants 

 at points where they root. We have a good example of 

 them in the Strawberry. Plants are also reproduced by 

 " suckers." These are underground branches which 

 have turned upwards in quest of light and air, as in- 

 stanced by the Raspberry and the Rose. Suckers also 

 grow from buds developed on roots. This happens 

 commonly in some fruit-trees, also in the Elm and Lilac. 

 In the House-Leek (Sempervivum tectorum, Plate LV.), 

 vegetative reproduction takes place by the formation 

 of short stolons in the axils of the outer leaves of the 

 rosette, and these stolons produce new plants, which 

 root, and are ultimately separated from the parent 

 plant. The phenomenon is illustrated in the plate 

 referred to. The Ground Ivy (Plate LVI.) is an instance 

 of a plant with a prostrate stem. Both the stem and 

 the shoots arising from it creep along the ground, and 

 root at their nodes. The original plant dies, but the 

 rooted branches, separated by its death, live on, and 

 perpetuate the species. 



Bulbs and Corms are also means of vegetative repro- 

 duction. A bulb consists of a series of underground 

 leaves, swollen, fleshy, and replete with reserve nutri- 

 ment — Examples, Tulip and Narcissus. A corm is a 

 swollen stem, also full of food reserves. It is typically 

 developed in the Crocus. A Potato is a tuber packed 



