Evening Primrose Family — Onagraceae
|A type of swamp willow-herb, Epilobium sp.|
Most of the species in this mid-sized family are herbaceous – their stems are soft and green and the simple leaves grow from the stem in opposite, alternate, or spiralling arrangements. When in bloom, the flowers are often showy, possessing four petals and four darker, narrow sepals that are arranged alternately on the flower head. Only one genus, the willow-herbs, Epilobium, occurs in the Arctic. The most common plants in this family are herbaceous – their stems are soft and green, not woody.
General Information and Anatomy
In general, Onagraceae plants are characterized by simple leaves that grow from the stem in opposite, alternate, or spiraling arrangements. When in bloom, the flowers are often showy and, when fertilized, the plants bear nuts, berries, or – more commonly – a capsule that splits to release seeds. The seeds are smaill, hairy, and produced in great numbers – they are well adapted for wind dispersal.
Epilobium palustre, the swamp willow-herb, favours wet, mossy tundra, but is also common in the damp, silty soils on the margins of streams and ponds in the Arctic. Flowering stems on swamp willow-herb arise from the tips of special slender stalks grown the previous year. The small, attractive flowers are violet, pink, or white. Epilobium palustre is known to hybridize with E. davuricum, the Davurian willow-herb, which grows in sheltered, damp habitats, in close proximity to swamp willow-herb.