Osmunda morphology



In Osmunda, and in many other ferns of similar habit, the rhizome is surrounded by the very hard leaf bases. Good sections of the central cylinder can be secured only by dissecting away these hard leaf bases and any hard portions of the cortex before attempting to cut sections. A short distance back of the growing point will be found a region which will show practically all the structures of the mature stem, which will be easy to cut. Even in this region the leaf bases should be dissected away. From the apical cell back to the region where the sclerenchyma is beginning to turn brown, the material is easily cut in paraffin. Older portions should be cut freehand. Osmunda affords an excellent illustration of the mesarch siphonostele.





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