A work trip gave me the opportunity to explore the large sand dune system at Coatham, part of Teesmouth & Cleveland Coast SSSI. It is a fascinating site where open mosaic habitats (developed over historic deposits of lime rich slag from the former steel works) and garden escapes blur into a full succession of dune habitats, from grey dunes on the landward side to a strandline community at the top of the beach.
Plants that caught my eye, and sometimes my nose, included:
The famed (see
British and Irish Botany) plant of Hart's Pennyroyal (
Mentha cervina) at the edge of a pond, one of just a handful of known locations in Britain. Unfortunately it was not in flower at the time of my visit.
The margins of the pond supported good numbers of Knotted Pearlwort (
Sagina nodosa), always a nice plant to find. These plants were prostrate and therefore probably var.
moniliformis. A trip later in the year would likely confirm, as the large buds forming now should start to drop off to give rise to new plants.
Within the pond was a large population of Horned-pondweed (
Zannichellia palustris). These plants had fruit on obvious stalks (1.5mm long, clearly apparent with the naked eye) from a common peduncle and are therefore, based on Stace 4, subsp.
pedicellatus.
Everywhere within the dunes and on the slag deposits was the dinky coastal form of Lady's Bedstraw (
Galium verum subsp.
maritimum), always a treat to catch in full bloom.
Perhaps one of the most exciting specialities of this dune system is Purple Milk-vetch (
Astragalus danicus), a species holding its own further north but increasingly rare and patchily distributed in England.
Equally exciting for me was this curiously short, multi-stemmed (branching from base) and broad-leaved centaury. This meets published descriptions for the very poorly recorded and known sand dune form of Common Centaury (
Centaurium erythraea var.
fasciculare). Thanks to Tim Rich for confirming my identification from photos. See the
BSBI Handbook and an earlier analysis of variation in Common Centaury in
Watsonia for further information. The pale flesh-pink flowers may or may not be relevant, depending on what other recorder's find in the field.
Another nice coastal plant is the dwarf dune form of Lesser Meadow-rue (
Thalictrum minus subsp.
arenarium). Some would have you believe this isn't a genuine entity. Bluntly, I don't believe them. Having previously seen its enormous rhizome system exposed by the wind; this is clearly a dune specialist and an important sand binding species at that. It would be interesting to know what the genetic evidence says about the validity of this species.
My dabbling in hawkweeds continued with a chance to examine the known population of Uig Hawkweed (
Hieracium uiginskyense), present in huge numbers in the dunes.
Several of the dune slacks were fragrant with the scent of carnations, traceable to plants of Marsh Fragrant-orchid (Gymnadenia densiflora). This species packs a real punch.
Equally fragrant and stunning was this escaped Honeysuckle (
Lonicera periclymenum var.
periclymenum 'Serotina') at the roadside.
To end with another garden plant. I am going to stick my neck out and say this is the hybrid lilac (
Syringa x hyacinthiflora), although I would have been happier if I saw it in flower. Long cultivated, I suspect this hybrid is overlooked elsewhere. This bush was notable for its more shrubby form and stubby heart shaped leaves.
