Some similarities to : Toothwort (Lathraea squamaria) which is much taller with a tier of similar-shaped flowers and has cream coloured flowers and also starts to flower a little later.

Uniquely identifiable characteristics

Distinguishing Feature :

Purple Toothwort is stemless arising straight from the rhizomatous rootstock. Devoid of chlorophyll and thus any green coloration it is saprophytic, un-able to photo-synthesize itself, and hijacks the root systems of other plants for nutrients. Surprisingly, it seems to be grown as a garden plant, since some books proclaim that it is occasionally naturalised, for example, on willows. If the seeds are planted in a garden near to a suitable host plant, it may be 10 years or so before any of the purple flowers appear. Firstly the (very brittle and deep) roots have to find a host and tap into it. Lacking chlorophyll, leaves would be pointless, and it possesses none.

Purple Toothwort is a perennial parasitic plant that is completely devoid of chlorophyll and therefore incapable of photosynthesizing. It parasitizes the roots of Alder, Poplar and Willow.

The large amounts of nectar the plant produces is, highly unusually, alkaline and smells of ammonia, NH₃, which has an unpleasant odour and is poisonous. It contains the ammonia as ammonium hydroxide, NH₄OH. The ammonia is thought to be produced from an initially slightly acidic exudate containing amino acids and enzymes. The nectar is contained within the nectarine chamber at the base of the corolla and which narrows at the top and is protected by a barrier of hairs. A water-jacket around the base of the corolla formed by the calyx keeps the nectar chamber cool by means of its own evaporation, limiting the evaporative losses of nectar. This water jacket must therefore be topped up by the plant. The nectar also contains 35% to 38% by weight of sugars. Bees pollinate the flowers attracted by the nectar - they tolerate the ammoniacal smell, which seems to exist to deter other insects, particularly ants.

The fruit it bears is 2-valved with each containing 4 or 5 seeds which are explosively released as the fruits split open (dehiscence).