5. NORTH AMERICA

Rocky Mountains have a rich mountain flora, but also the neighbouring mountain chains Cascades and Sierra Nevada (in California) have plants which do well with us.

Lewisia rediviva (bitter-root)

Rocky Mountains have a rich mountain flora, but also the neighbouring mountain chains Cascades and Sierra Nevada (in California) have plants which do well with us. Lewisia cotyledon comes in several colours, whereas the less known Lewisiopsis tweedyi has large peach-coloured flowers. The bitter-root (L. rediviva) is amazing when it flowers in early July. Then its leaves have withered down and the flowers grow directly from the rhizome, as if sprouting straight out of the gravel.

The genus beard-tongue (Penstemon) is another North American speciality with its 280 species. Phlox is a third one with c. 67 species (one in Siberia). The genus includes many beautiful mat- or cushion-forming species in addition to widespread garden hybrids. 

Three groups in the primrose family are also North American: Douglasia (or transferred to Androsace), shooting stars (Dodecatheon, now being transferred to Primula) and the Primula section Parryi. A number of striking species which occur north of the polar tree line in America are primarily grown in the American-Siberian section of our Arctic collection.