Bristly Locust
Robinia fertilis
Family: Fabaceae or Leguminosae
What it is like
Robinia fertilis is a deciduous Shrub growing to 2 m (6ft 7in) at a medium rate. See above for USDA hardiness. It is hardy to UK zone 5. It is in flower from May to June. The species is hermaphrodite (has both male and female organs) and is pollinated by Insects. It can fix Nitrogen. 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 cannot grow in the shade. It prefers dry or moist soil and can tolerate drought. It can tolerate atmospheric pollution.
Height (m): 2
Where it is found
Dry woodland and hillside scrub.
South-eastern N. America.
Conservation Status:
Countries/locations it is found in
How it is used
Food
Rating: 0
Medicine
Rating: 0
Other
Rating:
Plants produce an extensive suckering root system and can be used for soil stabilization on banks etc.
Soil stabilization: Plants that can be grown in places such as sand dunes in order to prevent erosion by wind, water or other agents.
Nitrogen Fixer: Plants that fix nitrogen in the soil
How it is grown
Succeeds in any soil, preferring one that is not too rich. Requires a well-drained soil, succeeding on dry barren sites. Plants are tolerant of drought and atmospheric pollution. The branches are brittle and very liable to wind damage. When plants are grown in rich soils they produce coarse and rank growth which is even more liable to wind damage. Plants sucker freely, the suckers have vicious thorns. Any pruning should be done in late summer in order to reduce the risk of bleeding. Hardy to at least -20°c. This species is very closely allied to R. hispida and scarcely merits specific rank. A very greedy tree, tending to impoverish the soil. 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.
Propagating it: Seed - pre-soak for 48 hours in warm water and sow the seed in late winter in a cold frame. A short stratification improves germination rates and time. Prick out the seedlings into individual pots when they are large enough to handle and grow them on in the greenhouse for their first winter. Plant them out into their permanent positions in the following summer. The seed remains viable for over 10 years in normal storage. Suckers taken during the dormant season.
Best place to grow: Woodland Garden Sunny Edge;
Habit: Shrub
Hardiness: 4-8
Growth: Medium
Soil: Light (sandy), medium, heavy (clay)
Shade: No shade
Moisture: Dry, moist