Common name: Boneseed
Scientific name:Osteospermum sanctae-helenae
(recorded by Melliss as Tripteris burchellii)
IUCN status: Endangered
Natural History
There is very little history on this on this species. Specimens were collected by the botanists Burchell in 1808, Mellis in 1867 and Kerr in 1955. This species was described as not uncommon by Melliss (1875) and very rare by Kerr (1970).
Boneseed grows in the very dry outer parts of the Island between 30 and 200 metres above sea level. It appears after the onset of the winter rain in July or August. Thereafter it grows quickly to produce flowers and then seed before dying back in the summer. In the past it would have grown alongside other endemic species: tea plant, scrubwood, salad plant, babies' toes and french grass and also the indigenous samphire. Now it grows alongside a mixture of native species: babies toes, french grass, salad plant and samphire and exotic species: ice plant, creeper, venus rose and atriplex.
It is found growing in several small populations around the Sandy Bay area stretching from the road leading to the white sands by the old lime kiln towards Lot's Wife ponds. In 1875 Mellis records this species as "not abundant" in this area and this remains the same today. However it does appear that numbers are increasing following the removal of goats from the area. Boneseed has also been recently recorded from close to the Asses Ears. Older sitings are recorded from Turk's Cap Valley, near Flagstaff, Frightus, Bencoolen, near Prosperous Bay Plain and South West Cliffs.
DESCRIPTION
Boneseed is a rough hairy herb with thin straggling stems that creep along the ground and long narrow grey green leaves. The plants are often found growing across the dry steep scree slopes of Sandy Bay and other areas listed above. The flowers are yellow, about 1.2 cm in diameter and daisy like (ray florets). The fruit is star shaped. The seeds, about 2 mm long are hard angular and sticky due to the short hairs which cover them.
NUMBER OF SURVIVING POPULATIONS
Several small populations of boneseed can be found in the Sandy Bay area. The plants spreading down the slopes often down small steep guts. Population numbers range from just two or three individuals to about 100.
Approximately 100 individuals were recorded from a population close to the Asses Ears. It is quite possible that several small populations survive scattered across the steep slopes and cliffs of the outer parts of the Island. Many of them not accessible.
This species does appear to be recovering well since goats were removed from the Crown Waste however, numbers still remain small and the species is still classed as endangered.
CONSERVATION RECOVERY PROGRAMMES
Boneseed like other dry-land endemic species, for example scrubwood and babies' toes are recovering naturally. There are no apparent immediate threats to the wild population. The Environmental Conservation Section (ECS) will continue to monitor population numbers and collect seed for storage as a safe keeping measure.
The ECS will be visiting Turks Cap to look for bone seed, map populations, count population numbers and collect seed. Further searches will continue in other areas.