Orange Sex
 
The life cycle of Citrus sinensis is, as with most plants, defined by an alternation of generations. This means that the sweet orange alternates between haploid (n) and diploid (2n) stages. The image to the right is a general life cycle for angiosperms. The left side of the image is a display of the development of a female gametophyte into an embryo sac and the right side shows a male gametophyte developing to produce a pollen grain (sperm). The bottom of the image is shows fertilization occurring to form a zygote which will turn into a seed. This is a form of sexual reproduction.
Citrus sinensis is characterized as being a hermaphrodite or heterosporous, meaning that it produces both eggs and sperm. For this reason it is capable of self-pollination. On the other hand cross-pollination occurs between different orange trees by pollinators carrying pollen from the flower of one tree and transferring it to the stigma of the flower on another tree. This is one of the main reasons C. sinensis grows fragrant flowers with nectar (see Adaptation). The life cycle and forms of pollination in C. sinensis are very similar to the Moth Orchid (Phalaenopsis amabilis).Adaptation.htmlAdaptation.htmlhttp://bioweb.uwlax.edu/bio203/s2008/beams_dani/http://bioweb.uwlax.edu/bio203/s2008/beams_dani/shapeimage_3_link_0shapeimage_3_link_1shapeimage_3_link_2shapeimage_3_link_3