Characters of the fruits and seeds are among important diagnostic character in many groups. Field collectors usually note down all characters which are likely to be lost in dried herbarium specimens such as colour of flowers and fruits, habit and habitat and so on. In case of fleshy fruits, it is mandatory to measure its length, breadth and diameter when fresh (in field). Next, most fruits and seeds have dimension. Example, in case of a globose fruit, diameter is sufficient but for ellipsoid or ovoid fruits you should measure the length and diameter. For flat fruits, length and breadth are sufficient. Same parameters are applicable for the seeds.

Thank you @ Tapas Chakrabarty Sir

Hi Keya, In general I would recommend to measure the 3 basic dimensions of your seeds (or fruits), that are the lenght, width and thickness. If there are plenty of measurable seeds (or fruits) I would suggest to measure at least ten replicates and use the averaged values for comparison. Seed experts suggest that seed shape is a more stable variable than the seed size. Therefore, shape descriptors are suggested to characterize the seeds (or friuts), that are slenderness and flatness. Slenderness = length / with, thus the value is equal to or larger than 1. Flatness = thickness / width, thus the value is equal to or smaller than 1.

Thank you for the suggestion @ Pèter Csontos Sir.