358 



GENERAL MORPHOLOGY OF PLANTS 



the soil and supply the water, and mineral and nitrogenous 

 foods. The fern plant, then, lives independently of any thal- 

 lus. The stems are very short and erect as in the Christmas 

 fern, or are creeping or underground rhizomes as in the poly- 

 pody, the sensitive fern, or the common brake, while in some 

 tropical ferns there are tall, massive trunks as in the tree ferns. 

 The leaves have a simple blade as in the " heart's tongue " 

 (Scolopendrium -vulgar e = Phyllilis scolopendrium}, or are once 

 pinnate as in the polypody and Christ- 

 mas fern, or twice pinnate as in many 

 others, while in the common brake 

 they are palmately branched, the main 

 branches being twice pinnate. The 



leaves of ferns are 



more conspicuous 



than the stems, and 



the leaf stalk is often 



mistaken for a stem 



by some. The ferns 



have no flowers ncr 



seeds. They are 



propagated chiefly by 



spores, though a few 



develop bulbils.* In 

 "Fruit" dots of the the " walkmg " fern 



common polypody fern. , 



the long, slender tips 

 of the leaves touch the ground, take root and develop a new 

 stem and leaves, thus acting like a stolon. The spores are 

 developed in spore cases (sporangia) usually clustered on the 

 underside of the leaves in groups or lines. The fern plant is 

 the second generation (spore plant or sporophyte). The first 

 generation (gamete plant or gametophyte), which is developed 



* Cystopteris bulbifera ( = Filix bulbifera) which grows along moist, shady 

 banks, and Asplenium bulbiferum which is often grown in greenhouses. In 

 the former species these bulbils fall to the ground and grow to new fern 

 plants. The bulbil of the fern is a bud developed on the leaf. 



Fig. 317- 



Fig. 318. 



"Fruit" dots of the maidenhair 

 fern. 



