Note on the question whether Alaria esculenta 

 sheds its lamina periodically or not. 



By 



F. Børgesen. 



Somewhat divergent opinions are found in the literature as to 

 whether Alaria esculenta corresponds with e. g. several Laminaria- 

 species in having a regular shedding of the lamina or not. Most 

 authors incline however to the first view. 



Harvey e. g. in "Phycologia britannica" writes about this 

 subject in the text to Alaria esculenta (plate 79): "It appears to 

 be perennial; the new growth being produced at the base of the 

 leafy-frond, as observed by Mrs. Griffiths in all the Laminarieæ. 

 This portion is always of a much paler colour than the old, and 

 soon after the commencement of the growing season, the line of 

 demarcation becomes distinctly visible: and when it has progressed 

 for some time, a contraction takes place at the base of the old 

 leaf, which gradually increases till the latter falls, and a new frond 

 is formed". After this description we may suppose that a regular 

 change of leaf should take place. 



Areschoug in "Observationes phycologicæ" pars V, p. 16 

 writes as follows: "Ex omnibus Laminariaceis, quæ nobis cognitæ 

 sunt, rem, de qua quæritur, quum respicimus, maxime recedit Alaria, 

 nam jam mensibus Septembri et Octobri emoritur ad oras Scandi- 

 navicas Alariæ esculentæ lamina, nulla ncva procreata. Sed rema- 

 nent sporophylla haud tabescentia autumno et hierne sporas spar- 

 sura indeque veteris laminæ functione apud Laminariaceas fungentia. 

 Vis Vitalis tarnen adest in trunco, nam fine Februarii et initio Martii 

 a mari Lofotensi extrahi possunt specimina, quæ habent laminam 

 usque 50 cm. longam et 20 cm. latam costamque 1 cm. latam. 

 Apud omnia specimina. quum minora et juniora, turn magna et 



Botanisk Tidsskrift. 28. Bind. 14 



