Seed Shape Quantification in the Malvaceae Reveals Cardioid-Shaped Seeds Predominantly in Herbs

Abstract

Seed shape in the Malvaceae and other families of the order Malvales was investigated. Seed shape was quantified by comparison with the cardioid. The J index is the percent similarity between both images, the seed and the cardioid, and similarity is considered in cases where the J index is over 90. Seed shape was analysed in 73 genera, and seeds resembling the cardioid were found in 10 genera, eight in the Malvaceae and two in the Bixaceae and Cistaceae. Seed shape was quantified by comparison with the cardioid in 105 species. A correlation was found between the values of the J index and plant form, with higher values of the J index in the seeds of herbs, intermediate-in bushes, and lower values in trees. The results suggest a relationship between seed shape and plant form, where seeds resembling the cardioid are associated with plants having small size.