Northern Ireland's Priority Species

Anagallis minima – chaffweed

 

Distribution map

Click here to view an interactive map of the Northern Ireland dataset as currently collated by CEDaR.
The map is generated through the NBN Gateway using their Interactive Mapping Tool.

 

Anagallis minima (L.) E.H.Krause
Family: Primulaceae

This insignificant little annual, almost moss-like in scale, is often only 2.5 to 4.0cm tall. It occurs in disturbed or otherwise bare, damp sandy or gravelly, acidic soils, often near the sea. In summer it produces tiny flowers, which are amongst the smallest of any species in Britain and Ireland.

In brief

  • It is found mainly on or near the north Antrim coast, but it has also been found in County Tyrone, on lake shores and quarries in a few places in County Fermanagh, and on the Copeland Islands, County Down
  • On account of its very small, totally unspectacular appearance and the fact that it sometimes grows cunningly concealed among procumbent pearlwort (Sagina procumbens)in bare patches in damp ground, or in very short, heavily grazed or trampled, grassy vegetation, it can very easily be overlooked
  • Although certainly rarer than it previously was, chaffweed probably is under-recorded.
  • It flowers and fruits from June to September
  • As far as we can tell from the relatively few records we have of the species, chaffweed has declined rather rapidly during the last eighty or more years, not only in Northern Ireland but throughout these islands
  • Many sites of the species, especially inland ones, appear to have been lost before 1930. In Middlesex, to take an extreme example, Chaffweed was last seen about 1800 A.D. (Kent, 1975); thus the decline has been a long one, likely accelerated since the 1930s by several revolutions in farming practices
  • Chaffweed has very little competitive ability, and therefore it relies on environmental stress, for example, light, nutrient-poor soil, grazing pressure or other forms of physical disturbance, including long periods of winter immersion, to minimise the growth of more vigorous neighbours.

Species description
A minute, erect, hairless annual with stems branched from the base. The stalkless, mostly alternately arranged leaves are oval and only 3 to 5mm long. The flowers are also stalkless, and each has parts in fours. The four pink or white petals are shorter than the pale green sepals, making the tiny flower so inconspicuous as to be negligible. The plant is slightly more noticeable when in fruit, for the swollen globular capsules are considerably larger than the flowers. The capsules resemble miniature unripe apples, and are white or cream in colour, often with a red or brownish tip.

Life cycle
Chaffweed can sometimes behave as a winter annual, the seed germinating in September or October and the plantlet surviving over winter. When this occurs it then grows on vegetatively in the following season, the lower branches spreading and rooting, until finally it reproduces in the summer. In this mode it can produce a small, bushy plant up to about 10 x 15cm in height and spread. Since the growth period is thus extended, the plant accumulates additional photosynthetic energy reserves, enabling it to flower, self-fertilise (often while still in bud) and fruit to an extraordinary degree. Spring germinated individuals can exhibit similar, though less extreme "exuberant" growth, if they happen to occur in favourable ground protected from almost all competition (Salisbury, 1968). Being an annual, the plant dies after it seeds, and the latter normally overwinter, dormant in the upper soil layer.

Similar species
The only two plants that might possibly be confused with chaffweed are its relative, sea milkwort (Glaux maritime) and another tiny annual, allseed (Radiola linoides) which often accompanies chaffweed. Sea milkwort is vaguely similar but has lower leaves that are opposite each other and somewhat fleshy. It typically occurs in salty conditions on the sea shore, is a perennial rather than an annual, and bears masses of small pink flowers along the upper stem. Allseed is more diffusely branched than chaffweed, has opposite leaves and very numerous flowers on short stalks, with tiny white petals. If not in flower, a hand lens may be needed for positive identification.

How to see this species
Chaffweed is found mainly on or near the north Antrim coast. It is a difficult plant to find on account of its very small size and its minute white flowers. It really does require a hands-and-knees approach to search closely for it from June to September when it is flowering and fruiting. The places to search are around bare, sandy mud patches in damp hollows in coastal sand dunes (that is, dune-slacks) or salt marshes, in sandy rock crevices on cliffs, on sandy or clayey mud or fine gravel of lake shores, and more generally by tracks, ruts and trodden short turf on paths through lowland sandy heaths and heathy woods on acid, occasionally peaty, soils. Chaffweed particularly frequents damp sandy hollows or ruts on tracks or around gateways where water lies during the winter. It sometimes associates with other diminutive, moss-like, rather weedy annuals such as procumbent pearlwort (Sagina procumbens), water-purslane (Lythrum portula (=Peplis portula)) and bristle club-rush (Isolepis setacea).

Current status
Although there are 67 records for this plant occurring in Northern Ireland, the plant has only been seen at around 11 sites well scattered throughout the area since 1975. A high proportion of these stations are on or near the north Antrim coast, but it has also been found on the Baronscourt Estate, County Tyrone, on lake shores and in quarries in a few places in County Fermanagh and on the Copeland Islands, County Down.

Why is this species a priority in Northern Ireland?

  • Rapid decline and rarity.

Threats/Causes of decline
Chaffweed has only been seen 15 times in Northern Ireland since 1975 at about 11 sites, so its current status in our area needs further investigation before we can conclude definitely what we already suspect, that it is a rare and declining species. The probable dwindling of the species is very likely a result of a combination of factors, including the move away from arable farming towards improved pastures throughout many areas of Ireland. This involves the widespread and repeated use of slurry, artificial fertilisers and herbicides, together with atmospheric nitrogen enrichment of the environment, some of which derives from combustion of fossil fuels. These changes accelerating during the last eighty years have encouraged the growth of larger, more vigorous plant species, raising their competitive ability to levels of aggression. Thus small, shallowly rooted, relatively ephemeral annual plants are more likely to be ousted than ever before.

Conservation of this species

Current action

  • Implementation of the Northern Ireland Habitat Action Plan for Mesotrophic Lakes.

Proposed objectives/actions

  • Maintain the number of viable populations of the species.

What you can do
Records of new sites and estimates or counts of the sizes of populations are always valuable. Please do not pick or collect any of this plant. However, do photograph it. Send information to The Botanical Society of the British Isles (BSBI), c/o Botany Department, National Museums Northern Ireland, 153 Bangor Road, Cultra, Co. Down, BT18 0EU or to CEDaR, National Museums Northern Ireland, 153 Bangor Road, Cultra, Co. Down, BT18 0EU, Tel: 028 9039 5256, cedar.info [at] magni.org.uk.

Further information

Links
Flora of Northern Ireland

A series of very good photographs is available at: www.biopix.dk

Northern Ireland Habitat Action Plans

Literature
Kent, D.H. (1975). The Historical Flora of Middlesex. The Ray Society, London.

Salisbury, E.J. (1968). The reproductive biology and occasional seasonal dimorphism of Anagallis minima and Lythrum hyssopifolia. Watsonia 7: 25-39.

Text written by:
Dr Ralph Forbes