Standard deviation of mass of seed (mythological Carat weight unit)

Value 2.47 mg
Organism Carob tree Ceratonia siliqua
Reference Turnbull LA, Santamaria L, Martorell T, Rallo J, Hector A. Seed size variability: from carob to carats. Biol Lett. 2006 Sep 222(3):397-400.PubMed ID17148413
Method Collection of seeds. To assess carob seed variability 28 trees from a collection at Sa Granja agricultural research station, Mallorca were sampled.
Comments This value for female trees. Hermaphrodite seed weight 176+-7.1 mg. The Carob seed is considered to have been used for as a standard weight unit, 24 seeds weighted like one Byzantine gold coin. The Carat was standardized as 0.2 g in the year 1907. Research has shown that variability in seed weight of carob is similar to that of seeds of 63 other species of trees. However, as seeds become larger there is less variability among them, and ability of humans to visually discriminate between seed weights to a degree of 5% may have led to choice of larger carob seeds as weight unit. Availability of tree around Mediterranean was another factor.
Entered by Uri M
ID 103349