. Dansk botanisk arkiv. Plants; Plants -- Denmark. C. H. Ostenfeld: Contributions to West Australian Botany. I. 37 They were very long; their apex was rounded, not truncate, and they had a much stronger and thicker consistency than the typical ones. I could not find any shoot of this peculiar sea-grass, only the long leaf-blades the bases of which showed that they were thrown off from the sheaths. Two intact leaf-blades were 80 and 105 cm long (thus exceeding P. australis, the longest leaf-blade of which was 65 cm). The breadth of the leaves also differs: P. australis P. sp. 6—11 mm 3—5 mm (av
. Dansk botanisk arkiv. Plants; Plants -- Denmark. C. H. Ostenfeld: Contributions to West Australian Botany. I. 37 They were very long; their apex was rounded, not truncate, and they had a much stronger and thicker consistency than the typical ones. I could not find any shoot of this peculiar sea-grass, only the long leaf-blades the bases of which showed that they were thrown off from the sheaths. Two intact leaf-blades were 80 and 105 cm long (thus exceeding P. australis, the longest leaf-blade of which was 65 cm). The breadth of the leaves also differs: P. australis P. sp. 6—11 mm 3—5 mm (average of 10 leaves: ) (average of 6 leaves: 4) In transverse section (Fig. 23) the aberrant leaves differed in several respects from the lea- ves of the typical P. australis. The epidermal cells have much thicker walls and they are elong- ated perpendicularly to the sur- face. The sclerenchyma-strands are more numerous, and while in the typical P. australis the strands are practically restricted to a subepidermal layer (besides the few scattered in the septa), in this case they are also com- mon in the outer parts of the mesophyll inside the subepider- mal layer. Other interesting points are that the lacunæ in the mesophyll are much nar- rower than in typical P. austr., and that the ordinary cells of the mesophyll are filled with large starch grains. I have never before met with this rich occurrence of starch in the mesophyll of any sea-grass. Apart from these differences, the structure of the leaf points to Posidonia, and the question is, strictly speaking, whether the aberrant leaves belong to some modification of P. australis, or represent a new hitherto unknown species of the genus. The insufficient material at hand does not justify any definite decision at present. I have mentioned it here only to draw the attention of some later observer to this problem which seems worth Fig. 23. Posidonia sp., fromCarnarvon. Transverse section of a leaf-blade. For expla
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