SEXUAL KEPRODUCTION 301 



impunity. This is the case with the Water Starwort 

 (Callitriche) and the Water Soldier (Stratiotes aloides). 

 On the approach of genial conditions, they resume 

 activity at the surface. But other aquatics in late 

 autumn produce short leafy shoots, which detach them- 

 selves from the parent plant, and sink to the bottom of 

 the water, where they root in the mud. They rest 

 during the cold season, but in spring grow vigorously. 

 The Curled Pondweed (Potamogeton crispus) is a common 

 instance of this mode of hibernation and vegetative 

 reproduction. 



Little plants destined to attain full growth frequently 

 grow from the radical leaves of the Ladies' Smock (Car- 

 damine yratensis, Plate XXIV.) when that plant thrives 

 in wet ground. Another excellent instance of the power 

 of a leaf, while still growing on the parent plant, to 

 produce plantlets occurs in a Fern much favoured by 

 cultivators — Asplenium Fabianum. These plantlets are 

 a most successful means of propagation. In some 

 grasses which grow at Alpine elevations, notably the 

 Alpine Meadow-Grass (Poa alpina) and the Sheep's 

 Fescue-Grass (Festuca ovina), plantlets are developed in 

 place of flowers, and these eventually become detached 

 and take root. 



Sexual reproduction dependent upon the fertilization 

 of the egg-cell by a male element has been fairly fully 

 considered in previous chapters, both in relation to 

 cryptogamic and Flowering plants. It remains for us to 

 make a pointed statement as to how in the latter pollen 

 may be successfully transferred from anthers to stigmas 

 as a vital preliminary to fertilization. This transfer is 



