Heterostyly
Two or three flower forms with styles and stamens at different heights, forcing cross-pollination between types.
Botany · also called pin and thrum
Definition
Primroses and cowslips have pin flowers with a tall style and low anthers, and thrum flowers with the reverse. Pollen from one type lands on a visiting insect at exactly the height of the other type's stigma, so effective pollination happens only between forms. Purple loosestrife goes further with three distinct heights, which Darwin studied at length and called the most remarkable arrangement he had examined.
Where the word gets used loosely
An easy thing to see with a hand lens and rarely noticed. It is also a reason single-clone plantings of primroses set little seed.
Plant records that discuss this
See also
Other botany terms
Sources
Sources
- Field Guide to the Bees of Great Britain and Ireland — Bloomsbury (2015) · Field guide
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