i 5 6 THE ROCK SPLEENWORTS. 



and spreads its fronds in green rosettes with very decor- 

 ative effect. The stipe and rachis are a shining dark brown 

 and the tiny, roundish, or slightly elongated pinnae, with 

 entire or toothed margins, are scattered along the latter 

 on very short stalks. Sometimes they are slightly dilated 

 on the upper side at base. The whole frond is seldom 

 more than eight inches long and half an inch wide. The 

 number to each plant depends upon its strength and 

 vigour. From ten to twenty is near the normal number, 

 though plants with more than fifty living fronds have been 

 collected. The sporangia are borne in linear sori on the 

 backs of ordinary fronds, several on each pinnule and ob- 

 lique to the mid-vein. This species has also been known 

 to produce a few sori on the upper surface of the pinnules. 



Although so small and delicate, the fronds last through 

 the winter and spring. Then, instead of the entire frond 

 dying, only the pinnules fall, leaving the polished dark 

 rachids standing in a circle about the new growth. One 

 seldom finds a plant without these relics of other days 

 which often greatly outnumber the living fronds. It is 

 said that only the early sterile fronds last through the 

 winter, but this needs verification. 



A few years ago, it was discovered that under certain 

 conditions the fronds are capable of movement. The 

 phenomenon is placed on record in the Botanical Gazette. 

 The observer found that by quickly bringing a pot con- 

 taining the growing plant from the ordinarily shaded 

 position into sunlight, or even bright daylight, the fronds 

 made rapid motions back and forth in a direction at 

 right angles to the plane of the frond and " more rapid 

 than the second hand of a watch, but with occasional 

 stops in the course of each half vibration." Only the 

 fruiting fronds have been found to move thus and these 



