The genus Lewisia belongs to the family Portulaceae and contains some nineteen species, all from the American Rockies from California in the south to Washington State and British Columbia in the north. The species can be divided into three sections; evergreen, semi-deciduous and deciduous.

The evergreen species are as follows:

- Lewisia cantelovii
- Lewisia columbiana
- Lewisia cotyledon
- Lewisia leeana
- Lewisia serrata
- Lewisia tweedyi

Only Lewisia cotyledon is readily available in garden centres, while of the others Lewisia columbiana and Lewisia tweedyi are often available from specialist nurseries. Potting compost for all of these should be one part John Innes No.3 compost to two parts peat and two parts grit. Care has to be taken to ensure that no water is allowed to stay in the centre of the leaf rosette as this can lead to rotting of the leaves and the death of the plant. This is especially the case for Lewisia tweedyi, which should only be allowed to obtain moisture from damp plunge material during the autumn months.

The only semi-deciduous species is Lewisia longipetala, which dies back to a small tuft of leaves and then is usually the last species to break into new growth in the spring. The potting compost is the same as the evergreen species with watering as for Lewisia tweedyi.

The deciduous species are:

- Lewisia brachycalyx
- Lewisia congdonii
- Lewisia disepala
- Lewisia kelloggii
- Lewisia maguirei
- Lewisia oppositifolia
- Lewisia pygmaea
- Lewisia rediviva
- Lewisia sierrae
- Lewisia stebinsii
- Lewisia triphylla

Of these, Lewisia brachycalyx, oppositifolia and rediviva are fairly easy to obtain. Lewisia congdonii, pymaea, sierrae, stebinsii and triphylla are occasionally seen.

With the exception of Lewisia rediviva, which should be kept dry duing autumn and winter, all the deciduous species should be kept just moist until growth commences and then given as much water as is required.

 

More information can be found in:

- 'Lewisias', by Roy Elliott
- 'The Genus Lewisia', by Brian Mathew
- 'Plants of Western Oregon, Washington and British Columbia', by Eugene N Kozloff

 

Photos:

- Lewisia cotyldeon (Taken by Roger Cove)
- Lewisia tweedyi (Taken by Roger Cove)
- Lewisia cotyledon (Taken by Roger Cove)
- Lewisia tweedyi (Taken by Cecil Tanner)