A Grammatical Dictionary of Botanical Latin

Cotyledon (Eng.noun): “the perishable lobe of the seed of plants” (Sweringen 1882); “the seed-lobes; the first leaves in the rudimentary plant or embryo” (Lindley); seed leaf (Jackson); also “seed lobe” (Jackson); “seed leaf, the first leaf from seed” (Paxton); “applied first by Linnaeus to the seed-lobes, the first leaves of the embryo, one in monocotyledons, two or more in dicotyledons, rarely a whorl borne by the radicle or caudicle” (Jackson); “the foliar portion or first leaves (one, two, or more) of the embryo as found in the seed” (Fernald 1950): cotyledon,-is (s.f.III), abl.sg. cotyledone, nom.& abl.sg. cotyledones.

Folium,-i (s.n.II) seminale, abl. sg. folio seminali: a cotyledon (Jackson), a ‘seed-leaf.’

“The seed (semen,-inis (s.n.III), is that part of the plant which is destined to its propagation. It consists of two halves, which change at germination into leaves, and are called seed-leaves or cotyledons (cotyledons,-um (pl.f.III))” (Willdenow).

[> L. cotyla,-ae, > Gk. kotyle, a cup, cavity; L. cotyledon, Gk. kotylEdOn, any cup-shaped cavity or hollow; the socket of a joint, as in acetabulum, q.v.]; also, “cotyledon,-onis (s.f.III) = Gk. kotylEdOn, a plant, navelwort: Cotyledon umbilicus, Linn.” (Lewis & Short)];

cotyledon,-is (s.f.III):

      singular        plural
Nom. cotyledon     cotyledones
Gen. cotyledonis   cotyledonum
Dat. cotyledoni    cotyledonibus
Acc. cotyledonem   cotyledones
Abl. cotyledone    contyledonibus

NOTE: although the base or stem has the same number of syllables in the nom.sg. and all other cases, it is not an i-stem noun.

Cotyledon, Linn. (= a genus} “from kotyle, a cavity; in allusion to the cup-like leaves. Crassulaceae” (Paxton; Stearn 1996).

The gen.sg.of the genus Cotyledon, used as an epithet: ‘with hollowed-leaves;” also “with leaves like the genus Cotyledon:”

=‘cotyledonis;’ Crassula cotyledonis = Globulea cotyledonis = Purgonea cotyledonis; Pelargonium cotyledonis, a fleshy, succulent plant; Senecio cotyledonis a fleshy, succulent shrub with small succulent leaves (like a Crassula).

NOTE: these are nouns in apposition.