Different lavender varieties can and do cross-pollinate, and this has implications for essential oil production, particularly concerning yield and chemical composition.
Here's how:
1. Increased Essential Oil Yield (Generally Positive)
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Pollination Boosts Yield: Studies show that cross-pollination by insects, primarily bees, generally leads to a higher yield of essential oil from lavender plants. Lavender plants that are pollinated produce more essential oil compared to those where pollinators are excluded. This is because pollination is crucial for seed production and overall plant vigor, which in turn influences the amount of biomass (flower tops) available for distillation.
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Commercial Practice: For this reason, many commercial lavender growers will even place beehives in their fields to encourage robust pollination and maximize their harvestable biomass.
2. Impact on Essential Oil Chemical Composition (Nuanced)
This is where cross-pollination becomes more critical for essential oil producers:
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Alteration of Key Compounds: While beneficial for yield, cross-pollination can subtly alter the chemical profile of the essential oil. For example, research on Lavandula angustifolia (True or English Lavender) has shown that pollinated plants, while producing more oil, may have:
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Lower relative amounts of linalool.
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Higher relative amounts of linalyl acetate.
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The balance of linalool and linalyl acetate is crucial for the characteristic sweet, floral, and highly valued aroma of "true" lavender essential oil. Other compounds like camphor and 1,8-cineole are typically desired in very low percentages for high-quality L. angustifolia oil.
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Maintaining Purity: For producers aiming for a specific, consistent essential oil profile (especially for markets like aromatherapy, perfumery, or pharmaceuticals where specific chemotypes are desired), maintaining the genetic purity of their lavender varieties is paramount.
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They typically achieve this by vegetative propagation (cuttings) from carefully selected mother plants. Cuttings are genetic clones, ensuring the new plants have the exact same essential oil profile as the parent.
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They might also consider spatial isolation between different lavender varieties to minimize unintentional cross-pollination if the nuanced chemical profile is a major concern for their specific product.
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Hybrid Oils: It's important to remember that Lavandula x intermedia (Lavandin) is itself a natural hybrid that occurred from cross-pollination between L. angustifolia and L. latifolia. Lavandin varieties (like 'Grosso' or 'Abrialis') produce much higher yields of essential oil, but their oil inherently has a different chemical composition, typically with higher levels of camphor and 1,8-cineole, giving it a more herbaceous, sharp scent. This is acceptable for many industrial uses (soaps, detergents) but is distinct from "true" lavender oil.
In summary:
Cross-pollination does occur between different lavender varieties for essential oil use. It generally increases the quantity (yield) of essential oil produced. However, for producers who need to guarantee a very specific and consistent quality or chemical profile (e.g., meeting ISO standards for Lavandula angustifolia), relying solely on cross-pollinated seeds is problematic. Such growers will prioritize propagating via cuttings and maintaining genetic purity to ensure the desired essential oil composition.
