Plant of the Month: April

Lathraea clandestina Common name: Purple toothwort Family: Scrophulariaceae Vital statistics Height and spread: 2cm (0.75in) x indefinite. Form: Parasitic perennial. Soil: Moist but well drained. Aspect: Partial shade. Hardiness:  Fully hardy.

Lathraea clandestine @ Hyde Hall

This small and unusual rhizomatous perennial is a parasitic plant which grows at the base of a host tree or shrub, this particular species as parasitic on willow (Salix), poplar (Populus) and alder (Alnus). It bears tiny, tubular, two-lipped mauve flowers which are borne just above the soil surface. This unusual perennial can be seen growing on the base of a willow (Salix) at the far end of the Top Pond at Hyde Hall. You will however have to look closely for this plant as the flowers appear literally just on the soil surface and are very small.

Lathraea

Lathraea is a genus of seven species of leafless, mainly subterranean, parasitic perennials that grow on the roots of trees or shrubs in damp woodland in temperate Europe and Asia. Each species parasitises specific trees or shrubs.

Lathraea comes from the Greek word lathraios meaning hidden, referring to its underground, parasitic existence.

Fleshy, ivory to mauve scales are produced on rhizomes, but no conventional leaves, and the flowers are tubular, two-lipped, white to mauve and borne in spring, at ground level.

The seeds are unusually large for a parasitic plant, being approximately 5mm in diameter and with four or five contained in a capsule. They are explosively ejected and may be thrown a considerable distance. The plant is associated with water, and transport of seeds or fragments of plant along watercourses may be one of its principal modes of dispersal.

Lathraea clandestina

This species grows on willow, poplar and alder.

 It has opposite, kidney-shaped, stem-clasping, scale-like, white leaves, up to 5mm (0.25in) long.

Unusual mauve flowers are produced in racemes of four to eight. They are tubular, two-lipped and up to 3cm (1.25in) long. They bloom in early and mid-spring and appear just above ground level.

The specific epithet clandestina means hidden, emphasising the underground nature of this species.

Cultivation

Grow in moist but well-drained soil in partial shade. Mulch with leafmould in autumn.

Lathraeas are generally free from pests and diseases.

Propagation

Scatter seed at the base of a suitable host tree as soon as ripe. However, seed is not easy to obtain commercially, so if possible detach a small clump from a parent plant and place it near the roots of the chosen host.

This is not the plant of choice for instant effect in the garden as it is sometimes 10 years before a flowering shoot emerges above the ground.