Scorpion Senna
Coronilla emerus
Family: Fabaceae or Leguminosae
What it is like
Coronilla emerus is an evergreen Shrub growing to 2.7 m (8ft 10in). See above for USDA hardiness. It is hardy to UK zone 6. It is in leaf all year, in flower from May to October. The species is hermaphrodite (has both male and female organs) and is pollinated by Bees. It can fix Nitrogen. Suitable for: light (sandy) and medium (loamy) soils, prefers well-drained soil and can grow in nutritionally poor soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It cannot grow in the shade. It prefers dry or moist soil and can tolerate drought.
Height (m): 2.7
Where it is found
Thin woodland and rocky places in limestone hills.
C. and S. Europe to N. Africa.
Conservation Status:
Countries/locations it is found in
How it is used
Food
Rating: 0
Medicine
Rating: 1
The plant is cardiac and diuretic.
Cardiac: Used in the treatment of heart problems.
Diuretic: Acts on the kidneys, promoting the flow of urine.
Other
Rating:
Nitrogen Fixer: Plants that fix nitrogen in the soil
Scented Plants: Plants noted for their scent
How it is grown
Succeeds in a sunny position in most well-drained soils, preferring a moderately rich loamy soil. An easily grown plant, it is hardy to about -20°c if it is sheltered from cold winds. Plants can be pruned almost back to the base if required, they usually resprout freely. The flowers are sweetly scented. This species has a symbiotic relationship with certain soil bacteria, these bacteria form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby. Plants in this genus are notably resistant to honey fungus.
Propagating it: Seed - scarify and then pre-soak the seed for 1 - 2 hours in warm water. A period of cold stratification is also said to be helpful. Sow the seed in spring in a greenhouse. Germination usually takes place in 4 - 6 weeks at 15°c. Pot up the seedlings as soon as possible into individual pots and plant them out in the following spring. Cuttings of greenwood, June in a frame with bottom heat. Cuttings of half-ripe wood, July/August in a frame. Cuttings of nearly mature side shoots, firm at the base and 7 - 10cm long with a heel, October/November in a frame. Plants are well rooted after 12 months. Good percentage.
Best place to grow: Woodland Garden Sunny Edge;
Habit: Shrub
Hardiness: 5-9
Growth:
Soil: Light (sandy), medium
Shade: No shade
Moisture: Dry, moist
Things to keep in mind
Although no mention of toxicity has been seen for this species, some members of the genus are poisonous and so some caution is advised.