Manipulated ground profiles to control surface run-off and prevent downstream flooding
A swale is a key technique for slowing heavy rain run-off by trapping the water and fltering it into the ground rather than let it accumulate in a wave of water creating floods and damage as shown in B and C. It also helps filter out pollutants and it will support damp-tolerant plants
Aralia cordata – Japanese spikenard
Clump-forming herbaceous perennial reaching up to 1.2m tall. Its large, compound leaves emerge golden-yellow in spring and maintain their gold colour when exposed to sun for a few hours each day. Tiny white flowers are borne on spikes up to 60cm tall in late summer, forming inedible purple berries in the autumn. Thickets and thin woods, especially by streams and ravines, all over Japan. E. Asia – China, Japan, Korea.
1-1.5 m H x 1-1.5 m W
It is hardy to zone (UK) 5 and is frost tender. It is in flower from July to August. The species is hermaphrodite (has both male and female organs) and is pollinated by bees.
Suitable for: light (sandy), medium (loamy) and heavy (clay) soils and can grow in nutritionally poor soil. Suitable pH: acid, neutral and basic (alkaline) soils. It can grow in full shade (deep woodland) or semi-shade (light woodland). It prefers moist soil.
Cinnamomum camphora – camphor oil plant
Evergreen. Native to China south of the Yangtze River, Taiwan, southern Japan, Korea, India and Vietnam, and has been introduced to many other countries. It grows up to 20–30 m tall. The leaves have a glossy, waxy appearance and smell of camphor when crushed. In spring, it produces bright green foliage with masses of small white flowers. It produces clusters of black, berry-like fruit around 1 cm in diameter. Its pale bark is very rough and fissured vertically. Banks of streams in China, to elevations of 750 metres. E. Asia – China, Japan. Locations within which Cinnamomum camphora is naturalised include Australia, southern USA, southern Europe, southern and eastern Africa, Madagascar and some oceanic islands with warm climates. It has been listed as noxious weed in South Africa and New South Wales and Queensland, Australia.
20-30m H x 7-8m W
Suitable for: light (sandy), medium (loamy) and heavy (clay) soils and prefers well-drained soil. Suitable pH: acid, neutral and basic (alkaline) soils and can grow in very acid and very alkaline soils.
It can grow in semi-shade (light woodland) or no shade. It prefers moist soil.
Elaeagnus umbellata – autumn olive
E. umbellata is a deciduous bushy shrub to around 5m tall and wide. Its leaves are narrowly oval with wavy edges, 5-10cm long, silvery when young before maturing to green but staying silvery beneath. Fragrant creamy-yellow flowers borne in small clusters in late spring to early summer are followed by egg-shaped silvery fruit that ripen to red. Thickets and thin woods in the lowland and hills. E. Asia – China, Japan, Himalayas.
4-8 m H x 4-8 m W
It can fix nitrogen. It is noted for attracting wildlife.
Suitable for: light (sandy), medium (loamy) and heavy (clay) soils, prefers well-drained soil and can grow in nutritionally poor soil. Suitable pH: acid, neutral and basic (alkaline) soils. It cannot grow in the shade. It prefers dry or moist soil and can tolerate drought. The plant can tolerate maritime exposure.
Eupatorium cannabinum – hemp agrimony
Juncus effusus ‘Spiralis’
Juncus effusus ‘Spiralis’ – corkscrew rush
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