Lathraea clandestina

RHS Plant Profile

hidden toothwort

Other common names

purple toothwort

Synonyms

Clandestina rectiflora

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Also known as Purple Toothwort, this is a leafless, harmless, parasitic plant, mainly feeding off hosts such as Willow, Poplar, Hazel and Alder but also ferns, herbs and other trees. For most of the year it is invisible, but from April to June, glossy, mainly dark, violet-purple, sometimes paler, crocus-like flowers appear. The seeds are ejected explosively allowing the plant to spread up to 8 metres. For further information, go to the RHS podcast at https://www.rhs.org.uk/plants/articles/wisley/wisley-plant-encounters/lathraea

Position

Full shade, Full sun, Partial shade

Soil Types

Chalk, Clay, Loam, Sand

Max Height

Up to 10 cm

Max Spread

4-8 metres

Size

Time to Maturity: 2–5 years
Max Spread: 4-8 metres
Max Height: Up to 10 cm

Growing Conditions

Chalk Clay Loam Sand

Moisture: Moist but well–drained
pH: Acid or Alkaline or Neutral

Position

Full shade Full sun Partial shade

Aspect: East–facing or North–facing or South–facing or West–facing
Exposure: Exposed or Sheltered
Hardiness

Hardiness Ratings

All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets

H1A: under glass all year (>15C)
H1B: can be grown outside in the summer (10 - 15)
H1C: can be grown outside in the summer (5 - 10)
H2: tolerant of low temperatures, but not surviving being frozen (1 to 5)
H3: hardy in coastal and relatively mild parts of the UK (-5 to 1)
H4: hardy through most of the UK (-10 to -5)
H5: hardy in most places throughout the UK even in severe winters (-15 to -10)
H6: hardy in all of UK and northern Europe (-20 to -15)
H7: hardy in the severest European continental climates (< -20): H7

Colour & Scent

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family: Orobanchaceae
Native to GB/Ireland: No
Habit: Matforming
Genus
Name Status: Correct
Plant Range: W Europe

How to Grow

Cultivation

Dig a wide hole next to the base of the host tree/plant (preferable Willow, Hazel, Alder or Poplar) and make a wound in the base of the host stem or trunk. Press the Lathraea next to this. Cover with soil, firm in and keep watered. It may take two seasons before there is any sign of growth, and due to the wide spread of the roots, the flowers may come up some distance from where they were planted

Propagation

Propagate by seed or root

Suggested planting locations and garden types

Cottage and informal garden
Ground cover

Pruning

No pruning required

Pests

Generally pest-free

Diseases

Generally disease-free