THE 
HEW PHYTOIiOGIST. 
Vol. 4. No. 8. October 25TH, 1905. 
SOME POINTS IN THE ANATOMY OF ACROSTICHUM 
AUREUM. 
By Ethel N. Thomas. 
[With Plates III. and IV, and Text-Figs. 27—40.] 
A CERTAIN interest attaches to Acrostichum aureum inasmuch 
as it is the only Vascular Cryptogam now known whose 
habitat is the salt-swamp. 
In view of the probability that many of our fossil Vascular 
Cryptogams were swamp-plants the investigation of this Fern 
seemed very desirable. Professor Oliver therefore suggested that 
I should examine material sent to him from Ceylon by Mr. 
A. K. Coomdraswamy. 
Acrostichum aureum (==Chrysodium vulgare), so called from the 
colour of its young leaves, is a handsome plant of bush-like growth 
forming a marked feature of the Mangrove Flora of Ceylon * 1 . It 
has an erect stem with long up-standing pinnate fronds, the upper 
pinnae of which are slightly smaller and fertile. From among the 
bases of the fronds numerous stout roots descend almost vertically 
in a tangled weft. 
Adaptation to Conditions. 
It is the roots which show the most interesting modification in 
connection with the peculiar mode of life. Each root is clothed 
with a soft brittle tissue which drops away in patches, leaving the 
central strand exposed—like a wire imperfectly covered with wool. 
This appearance is found on sectioning to be due to a great 
development of the middle cortex, which is furnished with huge 
lacunae (PI. III., fig. 3). The cells lining the lacunar chambers are 
very irregular in shape, and connect up with one another by 
numerous short arms. The membrane between the arm of one cell 
and that of another is sclerised, and perforated with numerous 
scalariform or rounded pits (PI. III., fig. 1). 
1 Tansley and Fritsch. “The Flora of the Ceylon Littoral,” 
New Phytologist, Vol. IV., Nos. 1, 2 and 3, 
/ 
