Mānuka plant, bees & New Zealand origin
Nectary photosynthesis contributes to the production of mānuka (Leptospermum scoparium) floral nectar
Authors: Michael J. Clearwater et al.
PLAIN-LANGUAGE SUMMARY
Experiments on attached and excised mānuka flowers measured gas exchange and chlorophyll fluorescence while varying flower age, temperature, light, sucrose and metabolic inhibitors, with additional 13CO₂ labeling. The results supported a measurable contribution from nectary photosynthesis, estimated at no more than about 20% of peak daily nectar sugar in the experimental system.
Reported result
Light, inhibitor and 13CO₂-labeling results supported a contribution from nectary photosynthesis to nectar sugars and DHA, while phloem import supplied most sugar.
Study design
plant-ecology
Mānuka plant, bees and New Zealand origin
Tested material
Attached and excised flowers of clonally propagated Leptospermum scoparium cultivar Martinii, nectar and metabolic-inhibitor or isotope-labeling preparations; no retail honey was tested.
Limitations
The authors caution that high PLP concentrations may have caused nonspecific metabolic inhibition, microbial production of nectar DHA was not excluded, and the proposed DHA-forming dephosphorylation step remained unresolved. The experiments used one cultivar and nectar traits varied with age and environment.
Funding & conflicts
Support included the University of Waikato, Auckland Botanical Society Lucy Cranwell Student Grant, Māori Education Trust, Tūhoe Education Contributions, KiwiNet PreSeed Accelerator Fund and New Zealand MBIE Endeavour Programme C09X1608. No competing-interest statement appeared in the accessible publisher record.
Applicability guardrail
Results from one experimental plant system do not determine the composition, grade, authenticity or health effects of finished commercial honey.
Scientific reference
Michael J. Clearwater et al. (2021). Nectary photosynthesis contributes to the production of mānuka (Leptospermum scoparium) floral nectar. New Phytologist. https://doi.org/10.1111/nph.17632
Editorial record
Responsible publisher: Manuka Drops Limited. Record updated: 2026-08-28. Retraction check recorded: 2026-08-27. Retraction status: checked-no-retraction-signal. Editorial status: published. Read the methodology.
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