Bladder Senna
Colutea arborescens
Family: Fabaceae or Leguminosae
What it is like
Colutea arborescens is a deciduous Shrub growing to 3.6 m (11ft) by 3 m (9ft) at a fast rate. See above for USDA hardiness. It is hardy to UK zone 5. It is in flower from June to September, and the seeds ripen from September to October. The species is hermaphrodite (has both male and female organs) and is pollinated by Bees. It can fix Nitrogen. It is noted for attracting wildlife. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils, prefers well-drained soil and can grow in nutritionally poor soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It prefers dry or moist soil and can tolerate drought. The plant can tolerates strong winds but not maritime exposure. It can tolerate atmospheric pollution.
Height (m): 3.6
Where it is found
Open woods, roadsides, railway banks etc, often on calcareous soils.
S. Europe - Mediterranean. Naturalized in Britain.
Conservation Status:
Countries/locations it is found in
How it is used
Food
Rating: 0
Medicine
Rating: 2
The leaves are diuretic and purgative. The leaves are sometimes used as a substitute for senna as a laxative, though they are much milder in their action. The plant is rather unreliable when used medicinally so is rarely employed in herbalism. The seeds are emetic. They are also toxic.
Diuretic: Acts on the kidneys, promoting the flow of urine.
Emetic: Induces vomiting.
Purgative: A drastic laxative causing a cleansing or watery evacuation of the bowels, usually with a griping pain.
Other
Rating: 4
The plants have an extensive root system and are used to stabilize banks and prevent soil erosion. Can be grown as a hedge. Nitrogen Fixer.
Hedge: Plants that can be grown as hedges.
Soil stabilization: Plants that can be grown in places such as sand dunes in order to prevent erosion by wind, water or other agents.
Attracts Wildlife: Plants noted for attracting wildlife
Food Forest: Plants for Edible Forest Gardens and Food Forests.
Hedge: Hedge
Nitrogen Fixer: Plants that fix nitrogen in the soil
How it is grown
An easily grown plant, it tolerates most soil conditions other than a water-logged soil. Prefers a position in full sun but tolerates light shade. Grows well on dry sunny banks. Dislikes strong winds, though another report in the same book says that it tolerates salt-laden winds. In our experience the plants are very subject to wind-rock when grown in a windy site. Tolerates atmospheric pollution. A fast growing plant, thriving on poor soils. Plants are hardy to about -20°c. Slugs love the young seedlings. Flowers are produced on the current season's growth. These flowers are very attractive to bees. Plants in this genus are notably resistant to honey fungus. 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. The plant is heat tolerant in zones 8 through 6. (Plant Hardiness Zones show how well plants withstand cold winter temperatures. Plant Heat Zones show when plants would start suffering from the heat. The Plant Heat Zone map is based on the number of "heat days" experienced in a given area where the temperature climbs to over 86 degrees F (30°C). At this temperature, many plants begin to suffer physiological damage. Heat Zones range from 1 (no heat days) to 12 (210 or more heat days). For example Heat Zone. 11-1 indicates that the plant is heat tolerant in zones 11 through 1.) For polyculture design as well as the above-ground architecture (form - tree, shrub etc. and size shown above) information on the habit and root pattern is also useful and given here if available. The plant growth habit is multistemmed with multiple stems from the crown.
Propagating it: Seed - pre-soak for 24 hours in hot water and sow late winter in a greenhouse. Scarification can help speed up the germination process. Germination can be slow and erratic, though treated seed usually germinates in 1 - 3 months at 20°c. As soon as they are large enough to handle, prick the seedlings out into individual pots and grow them on in the greenhouse for their first winter. Plant them out in late spring or early summer, after the last expected frosts. Cuttings of half-ripe wood, 7 - 10cm with a heel, July/August in a frame. Cuttings are not very long-lived.
Best place to grow: Woodland Garden Sunny Edge; Dappled Shade; Shady Edge; Hedge;
Habit: Shrub
Hardiness: 4-8
Growth: Fast
Soil: Light (sandy), medium, heavy (clay)
Shade: Semi-shade, no shade
Moisture: Dry, moist
Things to keep in mind
The seed is poisonous.