Anagallis minima (L.) E.H.L. Krause, Chaffweed

Account Summary

Growth form, preferred habitats and reproductive capacity

This rare, often minute, insignificant little annual (c. 7 cm in height), of regularly disturbed or otherwise open, damp or intermittently wet habitats and sandy or gravelly, acid soils, can very easily be overlooked on account of its unspectacular appearance. It is confined to lowland sites in B & I, on lakeshores and very often in coastal sites, including sand dune slacks, sandy sea cliffs and along paths and tracks on heathland and forest rides (A.J. Richards, in: Preston et al. 2002).

The axillary flowers, which are produced from June to August, are very tiny and the pink or white petals are shorter than the sepals, making the blossom so inconspicuous as to be easily overlooked. The flowers are self-compatible and frequently pollinate themselves while still in bud. Thus cool, wet summers with poor levels of sunshine do not preclude a normal crop of seed being set (Salisbury 1968). The plant is slightly more noticeable when in fruit, for the swollen globular capsules, white or cream in colour and often with a red or brownish tip, are considerably larger than the flowers. As a result of this and the moss-like scale of the plant (often only about 2.5-4.0 cm tall), there is a general recognition that A. minima is very probably under-recorded throughout B & I (Garrard & Streeter 1983; A.J. Richards, in: Preston et al. 2002).

Having said this, the Chaffweed plant can become larger and more noticeable if, as occasionally happens, it behaves as a winter annual. In this instance, which in some situations can represent around 3% of a population (Salisbury 1968), the seed germinates in September or October. Autumn seedlings usually survive overwinter, unless they are disturbed and they recommence growth in the spring, the lower branches spreading and rooting at their nodes, until the plant finally reproduces in summer. The winter annual mode of growth enables A. minima to produce a small, bushy plant up to 10 × 15 cm in height and spread. With its growth period thus extended, the winter annual plant accumulates additional photosynthetic reserves in comparison with spring seedlings, enabling it to flower and fruit to an extraordinary degree. While the typical April germinating spring annual produces an average of five fruit capsules, the winter annual can develop between 56 and 144 capsules. One exceptionally large winter annual specimen developed 443 capsules, containing on average of 16.4 seeds (Salisbury 1968). Spring germinating individuals can occasionally exhibit similar, though less extreme, exuberance of growth, if they happen to occupy very favourable ground, protected from almost all competition (Salisbury 1968).

Populations of A. minima have in the past been known to fluctuate widely in abundance at some sites, sometimes making a spectacular recovery from near absence, strongly suggesting the species can develop a long-term dormant buried seed store that in some seasons can produce a large seedling population after sufficient disturbance brings it to the soil surface (Salisbury 1968). Having said this, the survey of NW Europe soil seed bank literature did not feature any mention of A. minima (Thompson et al. 1997).

Fermanagh occurrence

There are a total of 16 records for A. minima from 14 tetrads in the Fermanagh Flora Database, but it has only been seen on four occasions since 1975. Thus the current status of Chaffweed in the area needs further investigation before it could be definitely concluded what is already suspected – that it is a declining species in this area. The local records are from damp, gravelly and sandy ground, mainly on the shores of larger lakes in Fermanagh and, as the tetrad distribution map shows, especially from around Lower Lough Erne. The details of the post-1975 records are: Muckross near Kesh, 1976, N. Dawson; gravel pit N of Derrin Mountain, 6 September 2001, RHN; Drumlish, 3 km S of Derrygonnelly, August 2002, R. Birch.

Irish occurrence

The Irish Flora (Webb 1977; Webb et al. 1996; Parnell & Curtis 2012) summarises the habitat preference and distribution of A. minima as being, "Lake shores and damp sandy places near the sea. Occasional in Kerry and the extreme North; very rare elsewhere." In its albeit very limited way, the Irish Census Catalogue lists at least one record of this species in 20 of the 40 Irish VCs. It also indicates (by means of brackets), that Chaffweed is considered extinct, or has not been observed for a long period, in five of these 20 VCs (Scannell & Synnott 1987).

The New Atlas enables us to add to this overall assessment the fact that A. minima has recently been found in several places in W Mayo (H27) and once in W Galway (H16), as well as in a few other scattered, almost entirely coastal sites around the country. The small number of inland records shown for Ireland in the New Atlas hectad map are almost all concentrated in the northern counties and the majority of these represent pre-1970 finds.

British occurrence

The New Atlas hectad map shows A. minima is widely, but intermittently scattered along the W & S coasts of Britain, becoming more prevalent northwards into W Scotland, including on the western isles. It has a limited presence inland and there is clear evidence, over the last 100 years or so, of a gradual decline towards near total absence along the E coast of England, which continues to this day (Salisbury 1968; A.J. Richards, in: Preston et al. 2002; Sell & Murrell 2014).

Likely causes of species decline in B & I

The dwindling of this usually very small, shallowly rooted species probably involves a combination of factors that have increased plant competition. These include the move away from arable farming towards 'improved' pastures throughout many areas of B & I, both for grazing and for silage-making. In turn, this entails the widespread and repeated use of slurry and/or artificial fertilisers and herbicides which is distributed in farm runoff and enters the general drainage water. In addition, there are the effects of a general atmospheric nitrogen enrichment of soils from pollution sources, including transport vehicle emissions throughout the country. These large, widespread environmental changes, that have been taking place throughout most of B & I during the last sixty years, very definitely encourage the growth of larger, more vigorous plant species, raising their competitive ability to levels of aggression, with the result that small, shallowly rooted, relatively ephemeral species like A. minima are more readily ousted than ever before.

European and world occurrence

A. minima is distributed over most of Europe, SW Asia and N. Africa. It is also present in both N & S America and regarded as native there by some, making it an amphi-Atlantic species. The current author (RSF) considers that the N American distribution mapped by Hultén & Fries (1986, Map 1482) looks decidedly patchy in comparison with that displayed in Europe and does not inspire confidence that it represents native occurrence. On the other hand, the species is small, insignificant-looking and easily overlooked, so the American map may only reflect poor recording. A. minima is definitely introduced in W Australia and probably so in other parts of the world (Hultén & Fries 1986).

Threats

Increased competition due to environmental pollution and nutrient enrichment.

• Find out more about the format of the species accounts
• View abbreviations
• View references for all species accounts
• View a gazetteer of all the sites