A furled fern frond. The picture shows a leaf of a male fern (Dryopteris filix-mas) that has emerged from ground level in April in the UK,against a background of expanded leaflets (green). The tissues of the young leaf - which first developed in the previous autumn - have a covering of scales (reddish brown) to protect them against cold and wet during the winter months. The leaf that will result from the tissues in this picture will be flat,with pinnate green leaflets,and up to 80cm long. The width of the picture frame is 10cm. This Spring growth does not involve the production of new cells or tissues; rather it is caused by extension growth of the walls of existing cells following water uptake. The spiral axis of the leaf shown here is converted into the straight midrib of a flat mature leaf simply by faster growth of the inner spiral walls of all the cells | |
Lizenzart: | Lizenzpflichtig |
Credit: | Science Photo Library / Burgess, Dr. Jeremy |
Bildgröße: | 3468 px × 5212 px |
Modell-Rechte: | nicht erforderlich |
Eigentums-Rechte: | nicht erforderlich |
Restrictions: | - |