Puzzling pearlworts at Clachtoll

October 14th 2020

Puzzling pearlworts at Clachtoll

In mid-July 2020, ‘Charlie’ Leeson approached the Field Club for help in identifying the wild flowers present in the garden ground surrounding her house at Clachtoll (NC0427).  This area, which amounts to about 100 sq.m., was sheep-fenced in autumn 2019 and appeared to contain a considerable variety (photo 1).

On 27th July we joined her, to work on the list she had started, finding 56 species in all.  They are a mixture of those found in the surrounding sandy maritime grassland, with others more typical of disturbed ground.  Examples of the former are sea mouse-ear Cerastium diffusum, smooth hawk’s-beard Crepis capillaris, lady’s bedstraw Galium verum, buck’s-horn plantain Plantago coronopus and wild thyme Thymus polytrichus.  The latter include burdock Arctium minus, toad rush Juncus bufonius, broad-leaved dock Rumex obtusifolius, prickly sow-thistle Sonchus asper and common nettle Urtica dioica.  Some of these are often described as ‘weeds’, but are, nevertheless, important food plants for butterfly and moth caterpillars and other insects.

Pearlworts

The paving around the house contributed to the list a number of tiny plants rooted in crevices.  These included common whitlow-grass Erophila verna and a variety of pearlworts Sagina spp.  The most obvious of the pearlworts were bright-green, sprawling perennial plants of procumbent pearlwort S. procumbens, which is found in open habitats throughout Assynt (photo 2).

However, two annual species caught our attention, since these are much less common locally.  They required close examination, with the help of a low-power microscope, to sort them out.

One, with ‘chubby’ leaves bearing minute points, and sepals with purplish margins, proved to be sea pearlwort S. maritima(photos 4 & 5)   This species evaded the authors of the Flora of Assynt (2002), but has since been found on the coast at Achmelvich (NC0524) and on roadsides at Knockan (NC2010) and Strone Brae (NC0725).

The other was another annual with a branched sprawling habit, leaves with longer points and sepals with pale margins.  This eventually keyed out to annual pearlwort S. apetala (photos 2, 3, 4 & 6).  There has been considerable confusion, at both local and national level, between this species and its close relative slender pearlwort S. filicaulis.  Neither was recorded during the survey for the Flora of Assynt, but slender pearlwort has since been found on roadsides and similar places in a handful of places locally, including Lochinver Harbour, where material was gathered the following day to aid identification.  This record of annual pearlwort appears to be the first reliably-named one for Assynt.

 

Ian M. Evans and Gwen Richards

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