Plant Heritage Spring 2002

More on names of Thymus

In the last issue of Plant Heritage, Margaret Easter described some of the work she is doing on sorting out the muddled naming of thymes.  In the following article she discusses some names of Thymus vulgaris cultivars and of golden thymes.

When I first went to see the thymes at Kew, I realised that the thyme known for many years as T. richardii subsp. nitidus 'Albus', had been wrongly assigned to this subspecies.  This thyme grows as a compact bush with tiny narrow leaves, whereas all the subspecies of T. richardii have a creeping habit with woody stems.  As it keys out as a cultivar of T. vulgaris it has been renamed T. vulgaris 'Dorcas' White' and this name has been listed in the RHS Plant Finder since 1998-99.  (Dorcas was a lady of means in the Acts of the Apostles who sewed for the poor and her name now appears on a box of pins.)

The thyme formerly known as miniature thyme or the invalid name T. compactus albus keys out as a cultivar of T. vulgaris.  It was given the cultivar name 'Snow White' in 1996 and is now known as T. vulgaris 'Snow White'.  It is more compact than T. vulgaris 'Dorcas White'.

The golden leaved thyme, for many years known by the invalid name T. ericoides 'Aureus', is similar to the thyme known as T. caespititius 'Aureus', but which bears no resemblance to the species.  In our first study the DNA profiles confirmed that these two names referred to the same plant and also show that they are cultivars of T. vulgaris.  As it is similar to T. vulgaris 'Dorcas White', but with golden leaves, it is now known as T. vulgaris 'Golden Pins' and this name has been listed in the RHS Plant Finder since 1998-99.

Golden thyme cultivars

For some while we have been questioning whether the native golden-leaved thymes have been assigned to the correct species.  Although they are lemon scented, their growth pattern differs considerably from that of Thymus citriodorus and its cultivars such as 'Golden King' and 'Golden Queen'.  These tend to grow as large loose bushes; the golden-leaved thymes grow as compact bushes, readily root at the leaf nodes and are similar to the native T. pulegioides.

Thymus citriodorus 'Archers Gold' was collected by Bill Archer in Somerset and T. × citriodorus 'Bertram Anderson' was named by Joe Elliott in honour of his friend E.B. Anderson.  Presumably they considered that as these thymes were lemon scented they must therefore be T. × citriodorus and so gave them cultivar names under that hybrid.  DNA studies have confirmed that these golden-leaved thymes are in fact T. pulegioides.  These thymes have now been renamed as cultivars of T. pulegioides.  Two other golden thymes, formerly grouped under citriodorus, namely 'Aureus' and 'Golden Dwarf' have also been reclassified under T. pulegioides.

The golden thyme known as T. vulgaris 'Aureus', which is thyme scented, has also been assigned to the wrong species.  Thymus vulgaris is not a native species, having been introduced by the Romans.  It is not fully hardy in Britain, particularly in the north.  The growth pattern of this thyme is unlike that of T. vulgaris, it does not key out to T. vulgaris.  It is similar to T. pulegioidesand DNA studies have confirmed this.  It is now known as T. pulegioides 'Goldentime'.

There are two other lemon scented thymes which are not now available in the nursery trade, but are mentioned in old catalogues and in Index Hortensis.  These were wrongly assigned to T. serpyllum.  DNA studies show that these thymes are also T. pulegioidesThymus serpyllum 'Aureus' is now T. pulegioides 'Elliott's Gold' (the earliest reference is Six Hills Nursery) and T. serpyllum 'Citriodorus' is now T. pulegioides 'Lemon King'.

Although initially these new names are likely to cause some confusion, as golden thymes are so readily available from most garden centres and many nurseries, it is important that the correct specific name is used from now on.  We hope that gardeners will adopt these new names.

Easter, Margaret (2002)  More on names of Thymus.  Plant Heritage, 9(1): 10-11.