Re: Why do tangerines have sections? Why are there different numbers of section

This is a very good question but it is often not easy to answer "why" 
questions like this. The fruit of the tangerine (Citrus reticulata) is a  
special type of berry termed a hesperidium, which has sections. The 
hesperidium evolved that way by chance and it was apparently a successful 
design. The function of a fruit is to protect and disperse the seeds. 
Tangerines are brightly colored and tasty so they proved successful 
in "bribing" animals to disperse the seeds. People especially have dispersed 
tangerines and other citrus throughout the world. Citrus (orange, lemon, lime, 
grapefruit, tangerine, tangelo, tangor, citron, etc.) are very important crops 
for fresh fruits and other uses such as a source of limonene in cleaning 
products, as fragrances, as a source of pectins used to make jams and jellies 
and various medicinal uses.  

Citrus seeds are damaged if they dry out so the juicy segments may function to 
keep the seeds moist.

Each section of a tangerine fruit is a chamber or locule of the ovary in the 
flower. Each locule contains one or more ovules. An ovule can develop into a 
seed. It is common for numbers of locules to vary slightly. Hortus Third says 
the number of segments varies from 10 to 14 for Citrus reticulata. 

Possible reasons why the number of sections might vary could be the size of 
the fruit or the number of seeds in the fruit. If a seed does not develop in a 
locule, then the segment may not develop. It might also be related to water or 
mineral nutrient availability to the tree, or amount of light. If the tree 
doesn't get enough water, light and mineral nutrients, there may not be enough 
energy for every fruit to develop the maximum number of segments.

References


Hesperidium definition


Citrus fruits


Citrus