The Morphology of Trichodiscus elegans, 
Gen. et Sp. Nov . 1 
BY 
E. J. WELSFORD, F.L.S. 
Research Assistant , Department of Botany, University of Leeds. 
CCURRENCE. In March, 1910, whilst examining some Azolla caro . 
lina growing in a glass jar of rain-water in the greenhouse of the 
Royal Holloway College, I found a small green Alga which I was unable 
to identify. The plants were growing in small circular patches on the glass 
and also in a few cases on the Azolla , but in this situation they were 
exceedingly difficult to see. 
The Azolla was bought in the previous November from Messrs. 
Ware and Sons, Limited, of Feltham, who had imported it from North 
Carolina, probably from Salem, and it is possible that the Alga was 
introduced from that district. 
Methods. Glass cover-slips were suspended in water against the 
side of a jar, and in a few weeks were covered with young Algae. Some 
of the slips were examined daily, and the development of the plant 
was studied in this way in the living condition. Material was also fixed 
in different stages of development in Flemming’s weak solution and in 
4 % formaldehyde. In the former case it was generally stained with 
haematoxylin or with brazilin, and mounted in Venice turpentine. 
Morphology. The Alga forms small circular green patches about 
1 mm. in diameter, and is firmly fixed to the substratum. It consists 
of a flat disc bearing numerous erect branches and long septate hairs. 
The disc is one cell thick and is formed of branched creeping filaments 
which cohere to form a pseudo-parenchymatous thallus, the peripheral 
branches of which are more or less free, and sometimes curve upwards. 
All the cells of the disc, with the exception of the rapidly growing free 
apices of the filaments, are capable of giving rise to one or two short 
erect branches ; these branches are more freely developed on old than 
on young plants. Hairs are not very numerous, and are usually found 
towards the periphery of the thallus. They are often 300 long, and 
1 A short account of this work was read before Section K of the British Association, at the 
meeting held at Winnipeg in September, 1909, and was published in the report. 
[Annals of Botany, Vol. XXVI. No. Cl. January, 1912.] 
