Plants of Cwm Idwal

There are several remarkable plants in Cwm Idwal, and most of the rarest plants belong to the Arctic-alpine taxon. As is clear from the name ‘Arctic-alpine’, these plants have settled in very cold climates as found in the Arctic, the high mountains of the Alps, and Cwm Idwal.

Areas within Cwm Idwal are an ideal habitat for some of these plants, that have adapted perfectly for living in such a place. Among the attributes of Arctic-alpine plants are that these flowering plants grow in low mats or ‘cushions’and they have a short flowering season, which protects them from the extreme elements found in these areas. These plants are usually found growing on high, north east facing ledges, usually above 600m.

One of the first Arctic-alpine plants to flower in Cwm Idwal is the Purple Saxifrage, or the Opposite-leaved Saxifrage, or to give its Latin name, Saxifraga oppositifolia. The Purple Saxifrage usually flowers from around mid-February through April, but the flowering season changes dependent on the winter weather we have in Cwm Idwal. There is rarely an opportunity to see the Purple Saxifrage flowering after Easter.

One of the most famous Arctic-Alpine plants that grows on the higher cliffs in Cwm Idwal is the Snowdon Lily. The plant grows in a few other locations in Eryri, but is found nowhere else in the British Isles. It flower only for a couple of weeks each year, its Welsh name “Brwynddail y Mynydd” means “Rush-leaves of the Mountain” and better reflects it’s rather inconspicuous appearance for most of the year.

Many other Arctic-Alpine species also grow in Cwm Idwal (some of which can be seen above, from top left to bottom right – Tufted Saxifrage, Mossy Saxifrage , Mountain Sorrel, Roseroot, Green Spleenwort, Moss Campion). These plants were common at the end of the last Ice Age, but have retreated to higher ground as the climate warmed up. Today they are still threatened by a warming climate. Other threats such as over collecting by Victorian botanists and intense grazing during the 20th century have means that there are very few places where these plants have survived. However work is being undertake to improve the fortunes of these species.

Cwm Idwal is an area where the annual rainfall is comparatively high. When water flows constantly through the soil, it washes the minerals, e.g. Nitrogen, from the acidic soil. Marshy soils are also more acidic, and this limits the number of species that can live here.

There are two particular plants in Cwm Idwal that have adapted for survival under such circumstances, which are Butterwort (Pinguicula vulgaris), and the round-leaved or common sundew (Drosera rotundifolia). These plants are different from other plants in Cwm Idwal as they trap and digest small insects. The plants have adapted to do this in order to acquire the necessary minerals for growth, flowering and seeding.