26o 



MORPHOLOGY. 



leaf appears as if it was rolled up as in fig. 2S7 of the rhristmas fern. As the 

 leaf elongates this portion unrolls. 



543. Longevity of ferns. — Most ferns live from year to year, by growth 

 adding to the advance of the stem, while by decay of the older parts the stem 

 shortens up behind. The leaves are short-lived, usually dying down each 

 year, and a new set arising from the growing end of the stem. Often one can 

 see just back or below the new leaves the old dead ones of the past season, 

 and farther back the remains of the petioles of still older leaves. 



544. Budding of ferns. — A few 

 ferns produce what are called bulbils 

 or hulblets on the leaves. One of 

 these, which is found throughout the 

 greater part of the eastern United 

 States, is the bladder fern (Cystop- 

 teris bulbifera), which grows in shady 

 rocky places. The long graceful 

 delicate leaves foi'm in the axils of 

 the pinnfe. especially near the end of 

 the leaf, small oval bulbs as sh^wn 

 in fig. 295. If we examine one of 

 these bladder-like bulbs we see that 

 the bulk of it is made up of short 

 thick fleshy leaves, smaller ones ap- 

 pearing between the outer ones at the 

 smaller end of the bulb. This bulb 

 contains a stem, young root, and 

 several pairs of these lleshy leaves. 

 They easily fall to the ground or 

 rocks, where, with the abundant 

 moisture usually present in localities 

 Pj where the fern is found, the bulb 



Cvstopteris bulbifera, young plant growing grows until the roots attach the plant 

 pinna m\''eaf.''^^ "^''^ '' ^''"'"^ ^'^"^^ '" ^'^^ ^^ ^" ^^^ ^^'^ ""^ ^^ ^^^ creviccs of the 



A young plant growing from 



rocks. 

 one of these bulbils is shown in fig. 295. 



545. Greenhouse ferns. — ^Some of the ferns grown in consen-atories h;ive 

 similar bulblets. Fig. 29(^1 represents one of these which is found abundantb 

 on the leaves of A^pleniuni bulbilcruni. These bulbils have leaves which are 

 very similar to the ordinary leaf eN:crpt that they are smaller. The 

 bulbs are al^i much more firmlv attached to the leaf, su that thev do not 

 icadily fall away. 



546. Plant conservatories usual h' furnish a nmnber of ver)' interesting 

 ferns, and enie shouM attempt to make the acquaintance of some of them, for 



