Trees with helicopter seeds

Helicopter seeds, or keys, are seeds with a papery wing that spins as it falls. Are they single or in pairs, and what angle do the wings make? Sycamore’s pairs meet in a V, Norway maple’s spread wide, field maple’s lie flat in a line, and ash hangs single keys in bunches all winter. Elm, lime and birch have winged seeds too, though they look nothing like a helicopter: a papery disc on elm, fruit hanging from a leafy strap on lime, and tiny winged seeds packed into birch’s catkins.

What to look for

  • SycamorePairs, the wings in a V
  • Norway maplePairs, the wings almost in a line
  • Field mapleSmall pairs, the wings in a line
  • AshBunches of single keys, held all winter
  • HornbeamThree-lobed leafy flaps
  • An elm, such as wych elmA round papery disc
  • A limeSmall fruit hanging from a leafy strap
Sycamore: keysYves Bas, CC BY 4.0SycamorePaired keys, wings set in a V Norway maple: keysNorway maplePaired keys, wings spread almost in a line Field maple: keysField maplePaired keys with wings set in a line Common ash: keysCommon ashBunches of biscuit brown keys, held all winter Hornbeam: seedsHornbeamHanging clusters of three-lobed leafy flaps Wych elm: seedsScott Shanks, CC BY 4.0Wych elmFlat papery discs, seed dead centre Common lime: nuts on strapsCommon limeHairy fruit hanging from a leafy strap Field elm: seedsJose Gutierrez Higa, CC BY 4.0Field elmPapery disc, seed up under the notch Japanese maple: keysJoão D'Andretta, CC BY 4.0Japanese mapleSmall reddish keys hanging in clusters Large-leaved lime: ribbed nutsLarge-leaved limeHard woody nut with five raised ribs Silver birch: seed catkinsAndrew Skotnicki, CC BY 4.0Silver birchCylindrical catkins that crumble into winged seeds
In the app

Not sure? Ask the app

  • Name it from a photoA leaf, the bark or a flower, and Treely names the tree
  • No signal? The guided keyOne simple question at a time, about what you can see
  • Every part, through the yearSo you can name it in winter as surely as in June
  • A short round each dayUntil you know them on sight
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Photographs: Yves Bas (CC BY 4.0), steve_mcwilliam (CC0), Leon Cross (CC BY 4.0), bobwardell (CC0), anniet39 (CC0), Scott Shanks (CC BY 4.0), Jose Gutierrez Higa (CC BY 4.0), João D'Andretta (CC BY 4.0), pilmar (CC0), Andrew Skotnicki (CC BY 4.0). With thanks to everyone who shares their photographs on iNaturalist and Wikimedia Commons.