Slight resemblance from afar to: Lesser Celandine. Both are extant around the same time, have deep-yellow single flowers, and occupy much the same niche: woodlands and copses. Lesser Celandine, however, has larger and kidney shaped leaves, with are not in a collar around the base of the flower.
Not to be semantically confused with : Winter Heliotrope (Petasites frangrans) or
Winter Jasmine [plants with a similar names belonging to a differing family]
Some similarities to : Globeflower (Trollius europaeus) in that the flower at first appears as a single sphere which belongs to the same Buttercup Family (Ranuculaceae) but that has totally different leaves.
Uniquely identifiable characteristics: The surrounding collar of deep-green leaves divided into pairs just below the single flower.
Distinguishing Feature : The un-branched single-stem bearing a single large globe-like flower with six deep-yellow petals.
Some relation to : Monk's-hood (a plant of similar name: Aconitum Napellus) [although both are in the same family, Ranunculaceae, they are in different Genera.
Winter Aconite (Eranthis Hyemalis) should not be confused with Monk's-hood (Aconitum Napellus), they possess totally different toxins for a start].
It is a winter-flowering garden plant that has naturalised extensively into woods, parks and roadsides. It grows in deciduous woodland flowering very early in the season when the forest canopy has not yet appeared and sunlight can stream down to the forest floor. Hyemalis is derived from the Latin and means 'winter-flowering'.
Winter Aconite contains several cardiac glycosides of the chromenone type such as
Eranthin A and
Eranthin B. It also contains another four different
4H-Chromenone Glycosides. They all exhibit negative inotropic activity. Ingestion of substantial quantities leads to symptoms of poisoning by cardiac glycosides: nausea, vomiting, diarrhoea, colic, bradycardia, disturbed vision, dyspnoea and finally cardiac arrest.
Shown is Eranthin only, being without any glycosides. [Your author cannot find the structural formulae for the glycosides Eranthin A or B]. The glycosidic groups will be attached where the hydroxyl ion is, replacing the hydrogen atom with a glycoside, or more in a chain of glycosides.
Chromenones such as this are presumably brightly coloured.