Bituminaria bituminosa (L.) Stirton

Synonyms - Psoralea bituminosa L.
Psoralea foetida
Psoralea palaestina
Psoralea plumosa
Aspalthium bituminosum (L.) Kuntze

Family: Fabaceae


Bituminaria and bituminosa refers to the bitumen or tar-like smell of the plant when crushed.
Tedera refers to the tea-like smell of the plants and hay.

Other Names:

Albo Tedera (var. albomarginata)
Arabian pea (var. bituminosa)
Engraisse mouton (var. bituminosa)
Pitch trefoil (var. bituminosa)
Scurfy pea
Tedera (var. bituminosa)
Teide Tedera (var. crassiuscula)


Tedera is a perennial, hairy, trifoliate leaved herb to 1 m tall with a characteristic smell of bitumen when crushed. It has blue flowers arranged in dense balls of 15-28 flowers and single seeded fruits with a long beak,




First leaves:


Smell like tar when crushed. Divergent (pinnate) veins.
Stipules - linear-subulate, persistent
Petiole - long.
Blade - 3 leaflets (trifoliate). Leaflets lance shaped and up to 60 mm long. Smooth margins or with tiny teeth, pointed tip, tapering to squarish base. Sparsely hairy. May have a few black dots on the surface.


Erect and highly branched. Thin with short white hairs that often point downwards.
The stems often go dark brown with age.
Flower stem - erect

Flower head:

Raceme with 16-24 flowers (5-16 triplets) in a semi spherical head. On peduncles from the leaf axils.
Flowers sessile or subsessile.
Each triplet has involucre bracts that are flap like with 3-5 teeth.


Pea type. Blue to violet with a whitish keel. 6 mm x 5 mm x 15 mm.
Ovary - superior, pubescent. Style up curved.
Sepals - fused to form the calyx about 12 mm long with 5 teeth and often lengthwise black streaks.
Petals - Standard, 2 wings and 2 keels. Standard is oval shaped and 10-12 mm long with 2 hidden small dark makings. The 2 wings are about 7 mm long. The keels have a lighter inner part with dark purple patches near the tips.
Stamens - United by their filaments. Intrastaminal nectary present.
Anthers - Yellow with yellow pollen. Oblong, alternately long-basifixed and short-versatile


1 seed per pod. Pod light brown.
Indehiscent, with a long sword shaped beak and furnished with glabrous spinulose or soft pubescent processes; pericarp adnate to seed or free.


Brown, egg shaped, 5 mm long.
Thousand seed weight of viable seed can vary from 20g (50,000 seeds/kg) to 30g (33,000 seeds/kg) (Correal et al. 2008), however, there is large variability for this character (Dini - Papanastasi et al. 2006).


Taproot and laterals with nitrogen fixing nodules.
Rhizobium relationships.
Bituminaria bituminosa nodulates readily in native environments and the root-nodule bacteria species is a mesorhizobium (Yates et al. 2009).

Key Characters:

Trifoliate leaves.
Bitumen like smell when leaves are crushed.
Blue to violet pea type flowers.


Life cycle:

It is able to grow all-year-round if not limited due to extreme drought during summer or very low temperatures during winter.


The leaves have a characteristic smell of bitumen or tar. The characteristic aroma appears to be the result of a combination of several substances such as phenolics, sulphurated compounds, sesquiterpenes and probably short-chain hydrocarbons.
The different botanical varieties of Bituminaria bituminosa have different frost tolerance. The least tolerant is var. albomarginata that is burnt by mild frost of short duration; however the plant is often able to recover. The var. crassiuscula is present at the top of the Cañadas area in Tenerife growing at altitudes over 2000 m above sea level close to Teide Mountain and some populations are under snow for 3 or 4 months. The var. bituminosa from high altitude sites from the Mediterranean basin is the most frost tolerant of all, being able to survive through severe winters with minimum temperatures lower than -10oC.


Terenti (2008) reported seed yields of up to 417 kg/ha In Spain, Correal et al. (2008) reported hand-harvested mean seed yields of 50g/plant for var. albomarginata, 38 g/plant for var. crassiuscula and 43 g/plant for var. bituminosa.
Breeding system
Bituminaria bituminosa is a self-pollinated (Juan et al. 2004) diploid species - 2n=20 (Stirton 1981).

Flowering times:

Bituminaria bituminosa is a long-day plant which flowers and set seeds mainly in the spring. However, low number of flowers can be found all year round.

Seed Biology and Germination:

Seed treatment before sowing
The seed is covered by the fruit and can not be separated for sowing. Scarification of the fruit enables water to penetrate the fruit easily and imbibe the seeds. Approximately 70% of seeds are hard and do not imbibe. For experimental purposes a small scalpel cut that can reach the seed coat will improve imbibition and germination.
Sowing depth and cover
Sowing depths of 3 cm have provided a good establishment across several soil types from sand to loam soils in Western Australia.
Sowing time and rate
In Mediterranean environments with mild winters, sowing as early as possible after the first rains is recommended to allow plants to reach their first summer with a deep root system. In regions with cold winters, early spring planting should be appropriate.

Vegetative Propagules:


There are a number of cultivars.
Bituminaria bituminosa var. albomarginata (Canary Islands): Albo Tedera
Bituminaria bituminosa var. crassiuscula (Canary Islands): Teide Tedera
Bituminaria bituminosa var. bituminosa (Canary Islands): Tedera and (Mediterranean basin): Arabian pea; Pitch trefoil; Engraisse mouton.
Bituminaria bituminosa var. hulensis (Hula Valley, Israel).


Population Dynamics and Dispersal:

This species is not a strong colonizer. However, some recruitment is found near the mother plants enhancing long-term persistence.
Ability to compete with weeds
Once established, the leafy and compact morphological types (mainly of var. albomarginata) are competitive with weeds by shading the area that they occupy. At the seedling stage, some of the var. bituminosa forms that have strong early vigour can be more competitive.
Response to defoliation / grazing
Plants are able to tolerate heavy sheep grazing 3 or 4 times per year depending on growing conditions (Real D., unpublished). There is no experience with continuous grazing, but rotational grazing with cattle seemed to be appropriate for the species (Sternberg et al. 2006). Goat grazing trials are being conducted during 2009 and 2010 at the ICIA, Tenerife, Canary Islands.

Origin and History:



Courtesy Australia's Virtual Herbarium.



Drought tolerance
The botanical varieties of Bituminaria bituminosa have different drought tolerance and associated mechanisms to tolerate or avoid it. Var. albomarginata is the most drought tolerant of all. It originates from Lanzarote Island (Canary Islands, Spain) which has 150 mm to 300 mm of annual rainfall with rainfall only during the winter months. However, due to its proximity to the ocean, the relative humidity is high. It is able to remain green during summer with minimal leaf drop. The other botanical varieties are also very drought tolerant but they tend to drop more leaves to reduce evapotranspiration under severe drought conditions (Correal et al. 2003).
Tolerance of flooding
Bituminaria bituminosa is a drought tolerant plant with poor tolerance to water-logging, except for var. hulensis that grows alongside water courses.
Rainfall requirements
The botanical varieties are adapted to different rainfall regimes. The var. albomarginata is adapted to low rainfall (<300 mm); the var. crassiuscula is adapted to 500 mm of annual rainfall and the var. bituminosa is the most broadly distributed in the Mediterranean basin and Macaronesia from low annual rainfall (<200 mm) at low altitude to high annual (>1000 mm) rainfall and high altitude.


It has a broad soil adaptation from deep sandy soils to stony shallow soils; however, in the Mediterranean basin, it is mostly found on alkaline soils. In the Canary Islands, Tedera can be found on soils with pH from 4.7 to 8.5.

Plant Associations:



Forage crop
Used for revegetating heavy metal contaminated or degraded soils.
Produces furanocoumarins (psoralen, angelicin, xanthotoxin and bergapten), compounds of broad pharmaceutical interest.
Dry matter yields
In Western Australia, in a region with 350 mm of annual rainfall, the dry matter production in experimental stands over 12 months was 5 t/ha, with half of this production occurring during the summer/autumn dry period (December to April). Under irrigation, 10 t/ha of dry matter has been produced per year. In the ICIA, Tenerife, Canary Islands, var. bituminosa had a production of 7 t DM / ha year and 14 t DM / ha year for first and second year stands respectively, while var. albomarginata had a yearly DM production of 2 and 7 t/ha for first and second year respectively (Méndez and Fernandez 1990).
Suitability for hay and silage
The traditional use of the Canary Islands is either direct grazing or as hay for milking goats (Méndez 2000).
Value as a stand-over or deferred feed
This species is able to remain green during long-dry summers in Western Australia without dropping its leaves. The capacity to defer plant production from one season to another (especially spring to summer) is one of the most valuable characteristic of this species.
Feeding value
Chemical analysis: The table below summarises the chemical analyses reported by (1)Real et al. (unpublished) (2) Pecetti et al. (2007), (3)Sternberg et al. (2006), (4) Ventura et al. (1999; 2000) and (4) Álvarez et al. (2004) from studies conducted in Italy, Western Australia, Israel and Spain.
  ReferenceNDF (%)ADF (%)ADL (%)CP (%)Diges(%)ME(MJ/kg DM)
var. albomarginata (summer)135.628.6  10.359.88.7
var. albomarginata (autumn)127.426.8  20.371.310.7
var. albomarginata (winter)125.821.9  17.667.910.9
Central Italy   
Calabria, Italy245.934.87.512.8   
Sicily, Italy250.838.68.210.9   
Israel325 to 39      48.9 
Canary Islands442.429.67.318.464.65.6
Canary Islands443.331.53115.662.07.9

Green feed
Cattle, sheep and goats (after a short period of getting familiar with the new fodder) eagerly graze var. albomarginata, var. crassiuscula and var. bituminosa from Canary Islands (Real, D. data not published 2008) and var. bituminosa from the Mediterranean basin during late spring, summer and autumn in Mediterranean environments (Gutman et al. 2000; Sternberg et al. 2006). During winter while there are many other very palatable options, Bituminaria is not preferentially grazed (Gutman et al. 2000). However, there is variability within the species for winter palatability.
Dry feed
The consumption of hay from var. bituminosa from the Canary Islands was compared to Lucerne hay and the former was preferred (Méndez 2000). The common name “tedera” in the Canary Islands refers to the tea-like smell of the plants and hay (P. Mendez pers. comm.). The common name “Engraisse mouton” used in some parts of France indicates the high feeding value of the species (G. Gintzburger pers. comm.). However, some accessions of var. bituminosa from the Mediterranean basin are considered unpalatable due to a strong tar-like smell. This characteristic aroma appears to be the result of a combination of several substances such as phenolics, sulphurated compounds, sesquiterpenes and probably short-chain hydrocarbons (Tava et al. 2007).
Anti-quality factors
There are four furanocoumarins (psoralen, angelicin, xanthotoxin and bergapten) present in leaves, stems and/or fruits of this species that vary in proportion with total concentration from 100 ppm to 8000 ppm (Innocenti et al. 1997; Martínez et al. 2009; Méndez et al. 2001; Tava et al. 2007; Zobel et al. 1991) Pterocarpan and chromene derivatives were also found (Pistelli et al. 2003). Furanocoumarins are correlated to photosensitisation in grazing animals (Oertli et al. 1984; Oertli et al. 1983). However, there are no reports in the literature or by farmers that Bituminaria bituminosa has caused photosensitization or any other health problem in grazing animals. Regarding other secondary compounds, a number of accessions were analysed in the Chemistry Centre of Western Australia and the content of total polyphenols was < 2% and the condensed tannins was <0.8% in a dry weight basis. Similar results were found by Pecetti et al. (2007) where total polyphenols were less than 1.4% in a dry weight basis.



No toxicity has been reported for Bituminaria bituminosa. There are only reports for some accessions from the Mediterranean basin of being unpalatable due to its smell.





Management and Control:

A number of herbicides can be used to selectively control it.


Eradication strategies:

Spray with metsulfuron or dicamba.

Herbicide resistance:

None reported.

Biological Control:

There are some reports of Rhizoctonia can affect root development in sandy soils in Western Australia (M. Gerding, 2008 pers. comm.). Some plants within the species are susceptible to blue-green aphid (Acyrthosiphon kondoi) but they appear to be resistant to spotted alfalfa aphids (Therioaphis trifolii) (R. Nair 2008 pers. comm.) and cowpea aphid (Aphis craccivora). Some plants have been infected by AMV (Alfalfa Mosaic Virus) causing a yellowing of leaves. At the ICIA, Tenerife, Canary Islands, severe infestations have occurred with Icerya purchasi (Homoptera (Hemiptera): common name cottony-cushion scale) pers. comm. P. Méndez.

Related plants:

Clovers (Trifolium spp.)
Beans (Vicia, Vigna & Phaseolus spp.)
Medics & Lucerne (Medicago spp.)
Lupins (Lupinus spp.)
Peas (Pisum spp.)
Serradella (Ornithopus spp.)
Soybean (Glycine max)
Tagasaste (Chamaecytisus palmensis)

Plants of similar appearance:


Bodkin, F. (1986). Encyclopaedia Botanica. (Angus and Robertson, Australia).

Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney).

Harden, Gwen J. (1991). Flora of NSW. (Royal Botanic Gardens, Sydney). Volume . P. Diagram.

Randall, J.M. and Marinelli, J. (1996) Invasive Plants. (Brooklyn Botanic Gardens Inc. Brooklyn). P. Photo.

Real, Daniel, Correal, E.,Méndez. P., Santos, A., Ríos, S., Sternberg, M., Dini-Papanastasi, O., Pecetti, L., and Tava, A. (2009) Bituminaria bituminosa C.H. Stirton. FAO.


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