Biomass and seed yield variation among 10 accessions of two Limnanthes species, L. alba Benth. and L. douglasii R. Br., was examined by way of a yield component analysis involving 17 morphological characters. Seed yield estimates ranged from 735 to 1680 kg ha−1. While both taxa contained populations with high yield potential, species differences in phenology and resource allocation suggested different strategies for yield optimization. L. douglasii accessions produced large quantities of small-sized seed, whereas L. alba entries maximized seed size at the expense of seed number, seed size and seed number being compensating components of yield in both species. Higher yields were associated with rapid initial growth and leaf development in L. douglasii, while delayed biomass accumulation and less leaf area appeared more favourable to seed production in L. alba. Early and asynchronous floral development were strong predictors of high yielding ability in both taxa. Selection for individuals which flower early and over a long period of time, with a higher seed output associated with a larger proportion of total above-ground dry matter allocated to reproduction, was suggested as an appropriate breeding strategy in either species. Concurrent improvement of seed number and seed size may prove possible by indirect selection for fewer flowers per plant in L. douglasii or more flowers per plant in L. alba accessions, through manipulation of primary branch length and number.