Osteospermum (Osteospermum spinescens)

Datasheet

Description

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Osteospermum spinescens, Photographer: C.Mayer

Osteospermum spinescens. Photographer: C. Meyer

Osteospermum spinescens. Credit: Joti Daya

Osteospermum spinescens. Credit: lorainevdb

Common names

Rivier draiboos, draiboos, appelbos [Afrikans] (Botha, 1938)

Species

Osteospermum spinescens Thunb. [Asteraceae]

Synonyms

Osteospermum pachypteris DC., Tripteris pachypteris Harv.

Taxonomic information

While Osteospermum spinescens is now considered to be a synonym of Tripteris pachypteris (USDA, 2019), a study from 1938 (Botha, 1938) considered that Tripteris pachypteris was different from Tripteris spinescens as the plants were extremely similar in appearance except for the presence of spines in T. spinescens.

Related feed(s)

Description

Osteospermum spinescens is a shrub native to the South African semi-arid veld regions, which is grazed by livestock and wild animals.

Morphology

Osteospermum spinescens is a small shrub 0.10-0.50 m high (Göhl, 1982; Strother, 2019). Under good conditions, it may reach a height of 0.90-1.10 m, but soil conditions and severity of grazing often limit its height to little more than 0.30 m (Botha, 1938). It has woody branches, stems that can turn spiny, lanceolate leaves, 1-2 cm long, yellow to orange flower heads about 1 cm in diameter on long pedicels, and three-winged fruit (Göhl, 1982; Strother, 2019). The twigs are succulent and have been described as soft and juicy when not lignified (Botha, 1938).

Uses

Osteospermum spinescens has been described in the 1930-1940s as one of the best pasture plants, both nutritive and palatable, found in its native range (Botha, 1938). It was then subject to overgrazing. More recent surveys only mention its palatability, which is considered to be low to moderate (Anderson et al., 1987; Du Toit, 2000).

Distribution

Osteospermum spinescens is native to South Africa and Namibia, where it is part of the veld flora, particularly in the Karoo region (USDA, 2019). It has been naturalized in New South Wales, Australia and in New Mexico, USA (Murray, 2015; Strother, 2019).

In the Karoo, Osteospermum spinescens normally occurs on low-lying ground, generally along the banks of ditches and rivers, in hollows and sometimes on flats. It is very hardy and can withstood excessive grazing. However, observers in the 1930s noted that the strands in the karoo veld in South Africa were suffering a lot from over-grazing wherever it occurred and was rapidly diminishing on many farms (Botha, 1938). Outside its native range, Osteospermum spinescens can be found in disturbed areas (Strother, 2019).

Nutritional aspects

Nutritional attributes

Osteospermum spinescens has a quite variable composition depending on age and on the selection of the plant parts. Its protein content is moderate to low, varying from 8 to 16.5% DM. Observations in 1930-1931 in South Africa shows a protein content highest in January-May (14-15%) and decreasing during the rest of the year (10-13%) (Henrici, 1932). A sample containing a large proportion of leaves and soft succulent twigs had a relatively high protein content (16.5%) and low crude fibre content (18.1% DM) (Botha, 1938). Other samples, which may include more lignified twigs and less leaves, had almost twice the crude fibre content (26-34% DM) and half the protein (8-9% DM)(Groenewald et al., 1967; Henrici, 1945). According to Botha, 1938, livestock graze the leaves and the succulent twigs preferentially.

Ruminants

There is limited information on the use of Osteospermum spinescens in ruminant feeding. The most complete data come from studies carried out in South Africa in the 1930-1940s where the plant investigated as an important component of the karoo veld. It was then regarded as one of the best pasture plants found in these semi-arid areas (Botha, 1938; Henrici, 1945).

Palatability

Early studies consider Osteospermum spinescens to be very palatable. The study by Botha, 1938, which describes what appears to be a spineless variety (then named Tripteris pachypteris), indicates that the spineless plants and the spiny plants are equally well grazed, practically throughout the year. In a first trial, the plant was well accepted by the sheep, who ate it completely including the dry twigs. However, for reasons unknown, the sheep refused to eat the plant when it was given to them a week later, though the material seemed identical. More recent studies show that Osteospermum spinescens is grazed by ruminants but is not very palatable, and has a medium-low grazing index value (Anderson et al., 1987; Du Toit, 2000).

Digestibility

Digestibility trials with sheep in South Africa in the 1930-1940s found a moderate to high OM digestibility: 52 and 67% in Botha, 1938 and Henrici, 1945 respectively. The higher digestibility value was obtained with samples containing leaves and succulent twigs (Botha, 1938).

Rabbits

No information seems available in the scientific literature on the use of Osteospermum spinescens for the feeding of domestic rabbits. In South Africa, the riverine rabbit Bunolagus monticularis, a wild endangered species, consider Osteosperum spinescens as a usual feed species (Hughes et al., 2008), but mainly consumed it during the dry season (from May to December) when other green plants are rare. However, the plant is generally avoided by riverine rabbits and has the lowest preference rating among 9 species available in late spring (Duthie, 1989).

Nutritional tables

Tables of chemical composition and nutritional value

Osteospermum (Osteospermum spinescens), aerial part

Avg: average or predicted value; SD: standard deviation; Min: minimum value; Max: maximum value; Nb: number of values (samples) used