Double flower
A cultivar bred with extra petals in place of stamens or nectaries — usually worthless to bees.
Botany · also called doubles, fully double
Definition
Doubling converts the reproductive parts of a flower into petals. A single dahlia offers an open disc of fertile florets and is worked constantly from July to frost; a pompom dahlia of the same species offers nothing whatsoever. The same applies to double hellebores, cosmos, calendula, roses, marigolds and a great many bedding plants.
Where the word gets used loosely
This is the single most consequential thing to check when buying plants for pollinators, and it is almost never on the label. The rule is simple: if you cannot see an open centre with visible stamens, neither can a bee.
Plant records that discuss this
- SageVery high nectar and only moderate pollen — sage feeds adult foragers superbly and contributes comparatively little to brood rearing, which is a common pattern in the mint family.
- DahliaGood for both in single-flowered forms across a very long late window, and close to zero in the doubles. The ratings here describe the single forms only.
- ZinniaA good late nectar and pollen source in single-flowered forms, and close to worthless in fully double ones.
See also
Other botany terms
Sources
Sources
- Field Guide to the Bees of Great Britain and Ireland — Bloomsbury (2015) · Field guide
- Bumblebees: Behaviour, Ecology, and Conservation — Oxford University Press (2010) · Monograph
How sources are selected and weighted is set out in the sources and evidence policy.