Germination and seedling emergence studies were made on seeds harvested from four different umbel positions of three cultivars of celery (Apium graveolens L.). Although heavier seeds were produced from primary umbels than from other umbels, these were less viable as measured by the germination percentage at I8°C in the light. However, germination of viable seeds from quaternary umbels was lower than that of seeds from primary umbels at 18°C in the dark when incubated with GA4, (2 × 10 −4M) and seed from secondary and tertiary umbels tended to be intermediate in response. All viable seeds germinated when N6‐benzyladenine (10−2M) was used in combination with GA4. Seeds from quaternary umbels of two of the cultivars had a lower high‐temperature limit for germination in the dark than did seeds from other umbels. In glasshouse experiments the emergence of viable ‘quaternary’ seeds of these cultivars was higher than that of ‘primary’ seeds. Under these conditions the time to 50% of the final emergence as determined after 42 days was similar for seeds from all umbel positions within each cultivar. In two varieties seedling weights were greater from seeds of primary as compared to quaternary umbels, and in general, the largest seedlings arose from the heaviest seeds and the smallest from the lightest seeds in all three cultivars.

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Wheat seeds (Triticum aestivum L. cvs. Yorkstar and Sirius) were cut transversely into embryoless and embryo‐containing (embryonated) halves and the content of endogenous cytokinins and gibberellins in both halves determined before and after the seeds imbibed water for 12–15 h at 22°C in the light. Dry seeds contained little ethyl acetate‐extractable gibberellin activity as measured by bioassay but n‐butanol‐soluble cytokinins were detected mainly in the embryoless halves. Dry, embryonated half‐seeds contained water‐soluble gibberellins which could be extracted into acidic ethyl acetate after treatment of the aqueous extract with either alkaline phosphatase, β‐glucosidase or a crude pectolytic enzyme preparation. When half‐seeds were allowed to imbibe water for 12 h and then extracted, cytokinin activity was largely lost from the embryoless halves and completely from the embryonated halves and water‐soluble gibberellins were also lost from the embryonated halves. However, ethyl acetate‐soluble gibberellins were present in the latter suggesting that “bound’ gibberellins were released during imbibition. The hormones present in normal and naturally embryoless dry grains of cv. Yorkstar were also determined. Both gibberellin and cytokinin activity was higher in normal grains suggesting that the presence of an embryo is essential for synthesis or accumulation of these hormones in the grain during development.