Re: Why do some carrots have twins?

Rest of question:

Why do some carrots look like they have grown together?
And does that have to do with the process of photosynthesis or storing 
starch?


Reply:

An edible carrot is an enlarged storage root which elongates from the tip. It 
also forms many thin lateral roots behind the tip that are lost when the carrot 
is harvested. Lateral roots originate deep inside the main root. At the tip of 
each root is an apical meristem, which is where cell division occurs.

I don't know for sure but one possibility is that twin carrots develop when the 
apical meristem is damaged or killed and one (if damaged) or two (if killed) 
lateral roots then begin a storage function. 

The above scenario is similar to what happens in shoots when the apical 
meristem in the terminal bud is killed or the terminal bud removed as in 
pruning. One or more shoot lateral buds will try to take over for the apical 
bud. Roots do not have buds as shoots do. 

The connection to photosynthesis is that the carrot storage root stores starch. 
If the main root tip is killed, then lateral roots have to take over the 
storage function or the storage root cannot continue to elongate and accumulate 
more starch. I have seen carrot roots with up to five "fingers".