The pattern of ponderosa pine (Pinus ponderosa) piperidine alkaloid accumulation from seeds to 28-day-old seedlings was assessed. Seeds were devoid of alkaloids but eight-day-old seedlings contained several alkaloids whose concentrations remained low with continued growth, while the concentration of pinidine [cis-2-methyl-6-(2-propenyl)-piperidine] steadily increased. C-13-Labelled cis-pinidinone [cis-2-methyl-6-(2-oxopropyl)-piperidine] was taken up through seedling roots and was incorporated into pinidine.