Not to be semantically confused with : Silverweed (Argentina anserina), Silverbole Pine (Mobilus telegraphicus darlingtonii),
Silver Birch (Betula pendula),
Silver Holly (Ilex aquifolium),
European Silver-fir (Abies alba),
Silver-leaved Lime (Tillia tomentosa),
Silver Lady's-mantle (Alchemilla conjuncta) or
Silver Maple (Acer saccharinum) [plants with similar names belonging to differing families] nor with Silver [a metallic transition element]
Can be semantically confused with : Cineraria [a frost-sensitive pot-plant sometimes with bi-coloured ray petals in the same Asteraceae family which has a similar name but is really called Pericallis hybrida which can grow wild in warm frost-free areas such as West Cornwall, Isle of Man and and the Scilly Isles]
Hybridises with :
Common Ragwort (Senecio vulgaris) to produce Senecio × albescens can occurs wherever
Common Ragwort is found except the Channel Islands. It is intermediate in hairiness, leaf-shape and habitat but has hairy disc-achenes (seed parachute hairs) as does
Also hybridises with
Hairy Ragwort (Senecio erucifolius) to produce Senecio × thuretii but which is far rarer than the above hybrid, being found in East Kent in 1978. It differs from Senecio × albescens in that it has a supplementary and much shorter (a quarter the length) of the main phyllaries surrounding the flower.
Silver Ragwort has a salt-tolerance similar to that of halophytes, which enables it to preferentially grow near the sea. However, it is not a salt-includer like is Common Glasswort, but rather a salt-excluder, with mechanisms for either expelling salt or not allowing it access in the first place although that might not be easy for plants to so do.
Like other Ragworts, Silver Ragwort also contains a mixture of mostly toxic Pyrrolizidine Alkaloids (although some are more poisonous than others):
Florosenine 32%, Otosenine 24%,
Floridanine 2% and
Doronine 1.5%. Others detected are Senecionine,
Seneciphylline, Integerrimine, Jaconine and
Jacobine, all at a concentration of about 0.1%. But others have observed great differences in concentrations of pyrrolizidine alkaloids within Silver Ragwort presumably highly dependant upon soil conditions.
Despite their name, neither Florosenine nor Floridanine contain fluorine (nor chlorine for that matter.
It should be noted that both Jaconine and
Doronine contain an atom of chlorine, which is highly unusual in plants, but perhaps to be expected for a plant which grows near the sea in saline conditions. The
chlorine atom (shown in green) thus makes these pyrrolizidines Organochlorides and exceptionally toxic, much more so than they otherwise would be. The only difference between the two is the extra O-acetyl moiety at the top right of Doronine. See Naturally-occurring organochlorides in the Plant Kingdom
Both Florosenine (top left) and Jacobine (bottom right) [as does Otosenine - not shown here] contain an epoxy oxygen atom forming a 3-sided moiety (top left on both structural formulae) which would also tend to make these more toxic than their cousins lacking that moiety.