This is for a chemistry experiment, so I just want to know if there are small traces of starch in oranges, and not whether or not I should eat an orange for its starch content, or something to that extent.
According to Healthy Eating, oranges contain 8.98g of sugar but does not contain any starch:
The natural sugar found in fruits doesn’t create such a big response because it's balanced by the fruit's fiber content. One banana has 14.43 grams of sugar, compared to only 8.98 grams in an orange. The biggest difference between the two is in the amount of starch each contains. The orange doesn’t have any, while the banana has 9.42 grams of starch.
Sources are varied. This paper studies starch in oranges (I can't access full paper). However, here authors mention that oranges contain practically no starch (beware, images are upside down). They refer to work by
Stahl A.L., Maturity studies of citrus fruits, 1938
and quote this work saying "starch content was measured to be 0.07-0.13%" in pulp of Pineapple oranges. Compare that to 22% of potato starch amount (dry mass).