acotyledonn.
/ˌeɪkɒtᵻˈliːd(ə)n/, /əˌkɒtᵻˈliːd(ə)n/, U.S. /ˌeɪˌkɑdlˈid(ə)n/ Botany. Now chiefly historical.
Any of the plants (including fungi) which have no distinct cotyledons (seed leaves), as certain parasitic plants, ferns, mosses, algae, etc.The acotyledons as a group, along with the monocotyledons and the dicotyledons, formed one of the major divisions of several early systems of botanical classification; its introduction under this name is usually attributed to Jussieu ( A. L. de Jussieu Genera plantarum (1789)).
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1798 Trans. Linn. Soc. 4 174 They [sc. broomrapes] are acotyledons; for, when a seed has attached itself to the root of any living plant, to which it is suited by its nature to adhere, it swells into a pellucid squamose gem or bulb.
1813 J. M. Good et al. Pantologia at Acotyledonous The distinction of vegetables into acotyledons, monocotyledons, dicotyledons..has been long made, and is the basis of Jussieu's natural arrangement.
1856 Crayon 3 365/1 The acotyledons (ferns, lichens, etc.) only very imperfectly represent the idea of the plant.
1874 F. A. Kitchener Year's Bot. 171 The very lowest sorts of acotyledons are plants formed of a single cell, and are only visible with the microscope.
1965 Amer. Biol. Teacher 27 792/2 These simple taxa..were replaced by the Phaenogamia and Cryptogamia series of Linnaeus..; the Acotyledons, Monocotyledons, and Dicotyledons of Antoine de Jussieu, [etc.].
1997 BioScience 47 243/3 The families were divided among 15 unnamed classes, which were themselves grouped into acotyledons (everything from fungi to cycads), monocotyledons, and dicotyledons.
This entry has been updated (OED Third Edition, December 2011; most recently modified version published online December 2021).
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