Common name: Dogwood
Scientific name:Nesohedyotis arborea
IUCN status: Critical
Natural History
The dogwood is a tree species of the tree fern thicket and can be found growing at the highest elevations on the island. It grows alongside tree ferns, black cabbage trees, whitewoods and ferns. It forms a dense spreading canopy that is able to catch the mist, often surrounding th Peaks, which then drips from the leaf tips on to the ground. It is thought that mist interception by plants could be playing a valuable role in the water cycle of the Island, by allowing more atmospheric water to become ground water.
DESCRIPTION
The dogwood is a tree up to seven metres tall. It has an upright branching pattern and often is multi-stemmed from the base. Growing on the steep slopes of the Peaks, dogwoods are often found which have partly collapsed, attached branc continues to grow below it and is easily mistaken for a second individual.
The leaves are lance shaped, smooth and a gloosy green colour. The inflorescence is borned at the tips of the branches and made up of many small bunches of white flowers only 2-4 mm across. There are two flower forms: male and female. Trees either bear male or female flowers and hence the dogwood is dioecious. Flowering takes place from December through to March. The fruit is a small dark brown capsule.
Like many of the St Helena endemic plants the dogwood has been so named because of its resemblance to a common European species, but which are not in any way related to: in this case the European dogwood.
NUMBER OF SURVIVING POPULATIONS
The massive reduction in the area of tree fern thicket and cabbage tree woodland on St Helena hsas reduced all of the tree species that grown in this habitat to small population numbers. The dogwood is the second most common tree species left on the Peaks after the black cabbage. Depsite this, it is only known from about 132 individuals. Of these Dr. Quentin Cronk determined that 69 were female with 17 undetermined. The largest populations of dogwoods can be found growing within Diana's Peak National Park. Small numbers are found between Coles Rock and Rose Cottage, High Peak and just two at the Depot.
CONSERVATION RECOVERY PROGRAMMES
Over the last two years seed from as many dogwoods as possible from sites where it grows hav been collected. The seed has then been sown in the nursery or put into storage for use at a later time. The dogwood has very high germination rates allowing many seedlings to be produced which have been replanted on the Peaks, along with the black cabbages, whotewoods, he cabbages and tree ferns, as part of the the Park management programme.
In addition to collect seed, cuttings have also been collected from as many indviduals as possible. These have been successfullyrooted in the nursery and will soon be planted out to be used as a seed orchard. A site has been selected within the National Park which will be used as the seed orchard for the dogwood and also for redwoods, he cabbages and whitewoods. The purpose of the seed orchard is to grow a sample of trees that represent the total variation found in each species. By growing a representative sample of trees of each species in one place we will be encouraging cross pollination, thereby maximising the future variation of the species. The endemic trees grow in a small numbers in many different sites at the Peaks, thus under natural conditions they are less likely to be abale to cross pollinate between the different populations. Variation is vitally important to the future survival of the species. Another benefit of having the trees in one place is that it makes seed collection easier as the trees are more accessible. The seed collected from the seed orchard will be collected and grown on at the nursery and the resulting seedlings used in the replanting programme on the Peaks.