A flowering female plant of Cycas revoluta,the Japanese Sago Palm,a primitive gymnosperm of the family Cycadaeae. The picture shows a developing cone at the centre of the whorl of leaves. The cone is comprised of modified leaves called megasporophylls,that produce ovules. These are fertilised by wind-borne microspores (pollen) from male plants in the vicinity. Fertilisation involves the development of motile spermatazoids,a primitive feature not found in higher plants except Cycads and Gingko.Cycads are present in the fossil record of the Devonian period,300 million years ago. C. revoluta requires frost protection in cool climates,and makes an easy,popular and slow growing house plant | |
Lizenzart: | Lizenzpflichtig |
Credit: | Science Photo Library / Burgess, Dr. Jeremy |
Bildgröße: | 3475 px × 5212 px |
Modell-Rechte: | nicht erforderlich |
Eigentums-Rechte: | nicht erforderlich |
Restrictions: | - |