Abstract: Variation in the seed size and seed mass in Hyptis suaveolens (L.) Poit. was studied and correlated with seedling establishment in a natural population. A two-fold increase in seed size and mass was observed in the large seeds over the small seeds. Large seeds showed a higher germination potential (78%) than smaller seeds (41%). α-amylase activity in large seeds was higher than small seeds. Endo-ß-mannanase expression in large seeds was detectable by Gel diffusion plate assay. Seedlings from large seeds were capable of emerging from greater burial depths. Total biomass and leaf area was greater in large seeded population in one-month seedling but subsequently after two months, the large and small seeded population showed no significant difference. Variation in seed size might be considered to be an adaptive response of H. suaveolens to its particular niche.