C. SKOTTSBERG 



Fig. 29. End of rhizome of Poly pod in 111 ittteniiediinii typiciDn ; the orbicular frond scars surrounded 

 by a dense whorl of narrow paleae. Nat. size. — Photo Mrs. M. f^rm. 



I. Rhizome 24.5 cm, i frond, and a short branch with another; the branch 

 was constricted at the base which explains why its frond withered first of all. 

 II. Rhizome 8.5 cm, with 2 fronds. 



III. » 1 5-5 * , * I frond. 



IV. » 17 » , » 3 fronds. 

 V. » 19 * > * 3 * • 



Thanks to its water storage a detached rhizome is able to keep the fronds 

 turgescent for many days, in cases for a month or more. 



When the experiment had been finished, the dry fronds were removed from 

 rhizomes II, IV and V and the rhizome and fronds weighed separately. The 

 result was: 



II. Rhizome 1.7, fronds 1.8 g 



IV. » 9.5, » 4.5 g 



V. » 8.9, » 1-7 g- 



A fresh frond weighs about 3 times as much as a dry one; in V, the 3 

 fronds should have weighed 5.1 g, the rhizome 20.7 g, while, 29/4 it weighed 

 8.9 g; in IV, where the fronds were much larger, their fresh weight would have been 

 approximately 13.5 g, the rhizome 28.6 g; 29/4 it weighed only 9.5 g. In II, the 

 fronds would have weighed 5.4 g fresh, the rhizome 9.6, reduced to 1.7 29/4. 

 The loss of water of the rhizome was 11.8 g in V, 19. i g in IV, and 7.9 in II, 

 or 57, 6^ and 82%, respectively. 



Ferns of the field strata. 



The abundance of ferns is a well-known feature in the physiognomy of the 

 plant communities and this applies not only to the wooded country but also to 

 the areas where the forest has disappeared. Of the arborescent species, Blecfniuni 

 cycadifolnwi, LopJwsoria and Dryopteris may form large beds, and several herb- 

 aceous species are still able to compete with the aggressive army of weeds now 

 filling the outer section of the valley bottoms and the lower, sun-baked slopes. 

 The most abundant of all is Blechmmi aurkulatum Cav., luxuriating in the closed 



