884 ^- SKOTTSBERG 



our many visits to Portezuelo de Villagra we noted that after a spell of dry, 

 sunny weather the carpets of Hyine^wpJiylluin along the trail had shrivelled, with 

 the pinnae and rhachis convolute, while after a drizzle and in misty weather they 

 had regained turgescence the next day, and it became evident that they did not de- 

 pend, or at least not only depend, on water taken up from the substratum but 

 were able to absorb moisture with their entire frond. In order to state the rate 

 at which turgescence is restored under different conditions, I made a few simple 

 experiments. 



Hxtnetiophyllum fuciforme. A specimen with one large frond was taken into the 

 laboratory 25/3 at i p. m., without removing the earth and moss. At 9 p. m. the frond 

 was dry and shrivelled. It was left like that to 4/4; when at 4 p. m., now very dry, 

 the earth and moss was well moistened and the plant placed under a bell-glass on 

 moistened filter-paper. At 9 p. m. 5/4 little effect was noticed, but 'after 1 2 hours 

 turgescence was getting restored. The frond was then detached; it weighed 4.52 g. 

 Left to dry to 6/4 at noon, when it weighed 4 g, it was sprayed, and placed under a 

 bell-glass at 4 p.m.; after 2 hours it had straightened the rhachis and unfolded the 

 pinnae, the weight then being 5 g. 



Hynienop/iyllui/i aineafufn. 



a) A tuft with moss and earth was placed in the laboratory 25/3 at i p.m. and 

 left to dry. At 9 p. m. the fronds began to wither. When completely dry, the plant 

 was dipped in water 4/4 at 4.45 p. m., taking care that the substratum was not mois- 

 tened. Already at 5.30 the frond segments began to expand, the rachis still being 

 rolled up, but half an hour later the plant looked perfectly normal. 



b) Six detached fronds, well dried so that they could be powdered by rubbing 

 them between your fingers, were weighed and put on a piece of wetted filter-paper 

 under a bell-glass 4/4 at 4.10 p. m., and the increase in weight noted: 4/4 4.10 p. m. 

 0-38 g; 5-3° P- m- 0.48 g; 8.30 p. m. 0.5 g; 5/4 7.15 a. m. 0.63 g; 8.30 p. m. 0.65 

 g; 6/4 8.30 a. m. 0.7 g; 8.30 p. m. 0.7 g. Turgescence was then completely restored. 



Hymenophyllum plicatum. A tuft with earth and moss was left to dry in the labo- 

 ratory 27/3 at 2 pm. At 8 p. m. all the fronds were rolled up and the plant left like this 

 until 4/4 at 4.30 p. m., when it was sprayed with rain-water. Already after 5 minutes 

 some effect was noticeable, and at 5.30 p. m. the fronds were once more turgescent. 

 Left once more to dry until 6/4, when at 9.35 a. m. it was again sprayed and put 

 under a bell-glass. Restored to turgescence at 10.30 a.m. 



Trichomanes exsectum. A detached frond weighing 0.5 g was left to dry in the 

 laboratory 7/4 at 2 p. m. and 13/4 at 3 p. m. put under a bell-glass with wetted 

 filter-paper, but without being in contact with this. Weight 13/4 at 3 p.m. 0.28 g, 

 13/4 9 p. m. 0.36 g, 14/4 9 a.m. 0.52 g and at 9 p.m. 0.52 g; turgescence then 

 completely restored. It should be mentioned that, under the microscope, the cells 

 had a normal appearance; this also applies to the 3 species of Hyme?iophylhwi. 



These simple experiments will show, I believe, that filmy ferns behave like 

 bryophytes and lichens and are able to stand desiccation for many days — very 

 likely much longer — without sustaining damage, and that direct absorption by 

 the frond from a film of water or from the humid atmosphere is a more import- 

 ant source of moisture than water taken up from the substratum. 



Water absorption by the leaves in higher plants has been investigated by several 

 authors. A synopsis was published by K. Wetzel in 1924 (Flora N. F. 17); his experi- 

 ments with plants from Temperate regions led him to the conclusion that such absorption 

 certainly occurs, but that it lacks biological significance. Recently (Oikos, Suppl. I, 



