Oysterplant

Mertensia maritima

Key facts

Gaelic name: Tiodhlac na mara (translation: gift of the sea)
Distribution: Orkney, Shetland, Fair Isle, Caithness and Sutherland
When to sea: May – August
Species on the Edge areas: North Coast; Shetland; Orkney

Species information

How to identify

Oysterplant grows close to the ground forming a mat of stems and leaves that is often roughly cirular. It has branching green or purple stems and blue-grey leaves that look quite thick and succulent. The stunning flowers are pink in bud and change to a lovely blue as they open. Flowers develop at the ends of the growing stems often around the edge of the plant. A strong taproot holds the plant securely in place and reaches deep down through the stones or sand to reach nutrients and freshwater.

Lifecycle

Plants start to appear in the stones or sand in May, and flower between June and August. They are at their most obvious in July, when large plants can be over 1.5m in diameter. In winter the leaves and stems die back, and the root system survives underground.

Distribution

Oysterplant can be found on the North Coast of Scotland, Fair Isle, Shetland and Orkney.

Habitat

The plant grows on gravelly and sandy seashores, at the top of the beach, usually just within reach of the highest winter tides. It is often the land plant that grows nearest to the sea. Plants that may grow nearby include sea sandwort and lyme grass.

On more exposed beaches, like some places in Caithness, it is most likely to be found where the beach is protected by offshore reefs and rocks. Oysterplant likes to grow near streams on the beach (occasionally plants have been found further up firths and river estuaries).

Threats

Sheep grazing
Human damage by trampling, vehicles and gravel collection
Climate change (however has both positive and negative impacts for oysterplant) – Oysterplant is adapted to cooler climates. Prolonged periods of hot weather are likely to be damaging for plants in summer, and warmer winters could affect seeds which need winter cold to promote germination. However, increasing frequency and severity of storm events may spread seeds more widely, resulting in new, wider spread populations.

What Species on the Edge is doing

Increased monitoring and surveying to locate strongholds, find new populations and better understand distribution and abundance
Training and supporting volunteers to survey oysterplant
Growing and planting oysterplants

What you can do for oysterplant

Sites where oysterplant grows vary from year to year as storms shift beach materials. Populations are most likely to persist in sheltered sites, whilst plants on more exposed sites can be short-lived. Climate change is likely to increase the frequency of storms and affect oysterplant distribution.

Regular recording each year is vital so we can monitor how Scotland’s oysterplants are doing. Here’s how you can help:

Familiarise yourself with what an oysterplant looks like.
Keep your eyes peeled and make a note of when and where you see oysterplants.
Send in your records here: sote@nature.scot.
If you can, please try to visit sites each year to check for presence of oysterplants.