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Dieren en planten

Water en land

Mens en Milieu

Sea buckthorn

size:

1 to 4.5 meters

color:

leaf: gray-green
flower: greenish

blossoms:

April and May

reproduction:

seed, root suckers

lifespan:

perennial

  • Dut: Duindoorn
  • Lat: Hippophae rhamnoides
  • Eng: Sea Buckthorn
  • Fren: Argousier
  • Ger: Sanddorn
  • Dan: Havtorn
Sea Buckthorn, Ecomare

Sea buckthorn

Sea buckthorn is best known when its bright orange berries ripen in late summer. Sometimes, you can even smell a sour odor given off by the berries. Migrating birds are attracted to these berries, which are rich in vitamin C. The berries are ripe just in time for these birds and provide them with extra energy to fly further. Brown-tail moths use sea buckthorn as a food plant for their caterpillars. It's not unusual to find cocoons from these hairy insects built around one or more branches. Sea buckthorn grows in soils rich in calcium. In the Netherlands, that means relatively younger dunes. The plant is found from Western Europe through to China.

On Texel


, Sytske Dijksen, www.fotofitis.nl

There are lots of sea buckthorns growing in the dunes, precisely along the route that the migrating birds take. As the name indicates, sea buckthorn is thorny. Before barbed wire was invented, dead branches from sea buckthorn were placed on top of the grassy 'tuinwallen' to keep the sheep from climbing over the wall.

  • Survival
    , Sytske Dijksen, www.fotofitis.nl

    Sea buckthorn can grow a half meter per year. Just like marram grass, the bush has little problem keeping pace with wind-blown sand. To prevent dehydration, the branches are covered with star-shaped scales, which protect the plant from direct sun rays. The scales are filled with air and give the bush a silvery-gray color.

  • Nitrogen machine

    Sea buckthorn uses a lot of nitrogen to grow. Its roots cannot supply sufficient amounts and therefore the plant has its own nitrogen machine. Bacteria, which grow in its root tubers, are able to fix nitrogen from the air. Tubers don't form on older roots and older roots don't rejuvenate. After around 7 years, the number of tubers strongly decline and 80% die off. After an average of 10 to 15 years, sea buckthorn plants slowly die and make room for other plants.

    The tubers produce more usable nitrogen than sea buckthorn needs itself. The excess nutrients are used by other plants that also require lots of nitrogen, such as stinging nettles, blackberries and eventually elderberries.

    Thanks to this 'nitrogen machine', sea buckthorn forms an important link in the dune community. Its berries and leaves are a source of food for many organisms and the plant is a hiding place for game (roe deer) and a nesting place for many species of birds.

  • New sprout

    A group of sea buckthorn bushes usually originates from one parent plant. Underground root stocks provide new plants. The group is then a new sprout and the bushes are all the same sex as the parent plant, either all male or all female. Once the berries appear, you can readily identify the females.

  • Drunken birds and hungry caterpillars
    Sea buckthorn in the winter, Ecomare

    The orange berries are very sour, which is proof of their high vitamin C content. With enough sugar, they make tasty jam, yoghurt and liqueurs. The pit in the berry is the actual seed. Many birds like to eat the berries. The hard seed is excreted, but rarely develops into an adult plant. Many young sprouts die from dehydration or are eaten by birds or rabbits. More importantly, the necessary bacteria which the sea buckthorn needs to grow are often lacking. Sometimes, the berries start to ferment on the branches. In that case, it is not unusual to see drunken migrating birds, such as fieldfares and redwings.