No relation to : Sea Milkwort (Glaux maritima), Milk Thistle (Silybum marianum), Purple Milk Vetch (Astragalus danicus), Lesser Milk-vetch (Astragalus odoratus), Alpine Milk-vetch (Astragalus alpinus), Milky Bellflower (Campanula lactiflora), Milk-parsley (Thyselium palustre), Cambridge Milk-parsley (Selinum carvifolia), nor with any of the ~30 other plants with 'Heath' in the common name such as Heath Dog-violet (Viola canina), Heath Groundsel (Senecio sylvaticus), Heath Pearlwort (Sagina subulata), Heath Wood-rush (Luzula multiflora), Heath Lobelia (Lobelia urens, Heath Rush (uncus squarrosus), Heath Fragrant-Orchid (Gymnadenia borealis), Heath Cudweed (Gnaphalium sylvaticum), Prickly Heath (Gaultheria mucronata), Heath Bedstraw (Galium saxatile), Sea Heath (Frankenia laevis), Cross-Leaved Heath (Erica tetralix), Darley Dale Heath (Erica × darleyensis) nor with Heather (Calluna vulgaris) etc. [plants with similar names belonging to differing families].

Usefully, this species of Milkwort does not hybridise with other Milkworts unlike the other three, Common Milkwort, Chalk Milkwort and Dwarf Milkwort.

Many similarities to : other Milkworts (Polygala species)

• DISTINGUISHING BETWEEN HEATH MILKWORT
  AND COMMON, CHALK AND DWARF MILKWORTS
• LENGTH OF PLANTS: Common Milkwort up to 30cm, erect or scrambling. Heath Milkwort up to 25cm scrambling to procumbent. Chalk Milkwort erect to ascending to 20cm. Dwarf Milkwort erect to ascending up to 10cm [16cm occasionally].
• LEAF ARRANGEMENT: Common Milkwort has leaves which are all alternate on the stem and do not form a basal rosette (as they do in Dwarf Milkwort). Chalk Milkwort produces an irregular false rosette of blunter leaves near the base (but stem bade leafless).
• LEAF SIZE DISTRIBUTION: Both Common Milkwort and Heath Milkwort have stem leaves which get smaller down the stem. [Whereas the leaves on both Chalk Milkwort and the very rare Dwarf Milkwort get larger lower down]
• NUMBER OF FLOWERS: Common Milkwort usually has more than 10 flowers (10 to 40 per spike) in its main stalk (any side branches may have fewer). [Whereas Heath Milkwort usually has less than 10 flowers (3 to 10) - but on Heath Milkwort, they can drop off leaving just the stump on the stem]. Chalk Milkwort has 6 to 20 per spike. Dwarf Milkwort 7 to 30 on main spike.
• COLOUR OF FLOWERS: The flowers of Common Milkwort can be shades of blue, purple, pink or white (as can those of Heath Milkwort). [The flowers of Chalk Milkwort are usually gentian blue and only rarely are they pink or white. The flowers of Dwarf Milkwort vary depending upon location: in the North they are blue or pink but in the South they are blue or greyish-white.]
• SIZE OF FLOWERS: Common Milkwort 4 to 7mm. Heath Milkwort 4.5 to 6mm. Chalk Milkwort 3 to 6mm. Dwarf Milkwort 2 to 5.5mm.
• VEINS ON PETALS: Common Milkwort has well-branched anastomising veins [which other milkworts lack (apart from the slight chance that Chalk Milkwortt occasionally may have sparingly anastomosing veins)]. Anastomosing means that the veins get more numerous towards the edge and moreover often curl back and intercept each other making an increasingly denser network the nearer the edge (see petals near the centre)
• HABITAT: Common Milkwort chalk or limey or acidic grassland, heathland and sand dunes. Heath Milkwort acid grassland or heathland. Chalk Milkwort and Dwarf Milkwort chalk or limestone grassland.
• RARITY: Common Milkwort and Heath Milkwort fairly common. Chalk Milkwort a slightly rare [R]. Dwarf Milkwort a very rare [RRR]

It is native and occurs frequently throughout most of Britain on acid grassland or heath (missing out on the sand-dunes and calcareous grassland which Common Milkwort also enjoys).