There are three plants with the common name including 'Alison', all belonging to the Cabbage Family (Brassicaceae) but with each in differing genera :
Sweet Alison (Lobularia maritima) The plant on this page
- Golden Alison (Aurinia saxatilis) with yellow petals.
Hoary Alison (Berteroa incana) very hairy with short white hairs.
Easily mis-identified as : Horseradish (Armoracia rusticana) which also has 4 white petals (but they are longer and cupped rather than splayed out planar), is about twice as tall, has flowers on longer stalks and many more of them (but like Sweet Alison has 6 yellow stamens) and has very long linear-lanceolate lower leaves (shorter up the stem) that are green rather than the grey-green of Sweet Alison). Sweet Alison has the clustered flowers in a hemisphere whereas Horseradish has them in an elongated cylindrical spike (albeit rounded at the summit).
Some similarities to :
Hoary Alison (Berteroa incana) but that has flowers with petals that are nicked to nearly half-way and is now only found growing wild within 60 miles of London. Also to Garden Arabis (Arabis caucaaia) which is also a garden escapee but grows slightly taller (to 40cm) but that has leaves that half encircle the stem (amplexicaul) and are sinuously toothed.
Slight resemblance to : Perennial Candytuft (Iberis sempervirens) which also has a (slightly elongated) hemispherical cluster of 4-petalled white flowers but there the outer two of the four petals on each flower are very much longer than the inner two.
Uniquely identifiable characteristics
Distinguishing Feature :
No relation to : Sweet Cicely (Myrrhis odorata) [a plant with similar name belonging to a differing family].
It is a sweetly fragrant flower, hence its name.
A neophyte grown in gardens from which it has escaped since the 1800's, inhabiting mainly coastal areas on sea cliffs and sand dunes and the dryer places of sandy shores, especially up against a wall. Less frequently found inland, especially in the central South of England. It is a low growing annual, biennial or perennial. The leaves are grey-green and hairy. Petals usually white, but are sometimes purple. Handling the plant can invoke an allergic reaction in sensitive folk.