Trichophorum cespitosum

Northern Deergrass

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Enter the name for this tabbed section: General
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A much more slender plant than most forms of T. germanicum, Common Deergrass: it often looks 'wispy' by comparison, with flexuous, wiry stems, and tufts which vary from quite dense to very open.

In dense vegetation of mineraliferous mires it can be quite inconspicuous and easy to overlook.

It is most obviously distinct from Common Deergrass when growing in mineral-rich seepage mires – often with relict species such as
Bartsia alpina and Tofieldia pusilla – where Common Deegrass is largely absent.

It is a particularly delightful find when fruiting vigorously in such mires, the tiny clusters of a few black-looking nuts almost invisible against 'busy' background vegetation, and appearing to the eye when a cluster of stems is cupped in the hand, or white paper is placed behind the tuft.

We now know it on ombrogenous (i.e. rain-fed) deep mires in Northern England and Scotland (see the "Habitats" button above, and the
Habitats page, and references, Sources/reading page).

The
Distributions map indicates its apparent rarity: some dots in southern areas may not correctly refer to this species, and (from Andy Amphlett's work in Speyside) it may well still be largely overlooked in other parts of Scotland.


See also the
hybrid page and especially the Identification pages for more detailed information.

Enter the name for this tabbed section: ID
You can download a simple chart for *field identification* as a two-page A5 PDF (114 KB; opens in a new window).

See the dedicated pages, Field identification ~ 1 and ~ 2 for much more detailed information.

Although externally similar, the two deergrass species are very distinct in their internal morphology, and readily separable: these are two good species!

The two species can be confirmed with a high degree of confidence by examination of their
stem cross-sections.

The
Hybrid Deegrass almost always grows near Northern Deergrass, and varies in stature so that it can appear very similar – indeed bridging the gap between the species and confusing the picture.

In the
early part of the growing season, mixed populations can be tricky to separate in the field. Length of sheath-opening provides the best guide at this stage.

Back home later, stem-sections of soft young emergent stems can be awkward to prepare and may be ambiguous until tissues mature.

Always remember that the hybrid is
sterile and through July drops its aborted flowers and glumes and so eventually appears almost completely 'bare-headed'.

So
the three taxa are much easier to separate from July onwards until dieback in September.

Note that the two species often fail to ripen fruit in some seasons, but then their spikes often retain the glumes, appearing distinctively bleached and pale in the late season, and thus different from the bare-headed hybrid.


Enter the name for this tabbed section: Habitats
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T. cespitosum tends to occupy areas with permanent water at its roots.

Distinctively, it occurs in +/- calcareous seepage mires (right), sometimes with relict species such as
Bartsia alpina and Tofieldia pusilla, or local species such as Eriophorum latifolium and Carex capillaris - habitats where Common Deegrass is absent.

It also occurs in the 'lagg-zone' of basin- and valley-mires - i.e where there is seepage of soligenous water into the mire from the surroundings.
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However, we now know it on ombrogenous (i.e. rain-fed) mires on deep peat in Northern England (right) and Scotland, in very species-poor acidic communities with no evident soligenous influence (see references, Sources/reading page). It occurs in similar mires in continental Europe.

The differences in habitat between these two types – mineral-rich and mineral-poor – is so striking that there may be different ecotypes involved. No morphological differences have yet been detected.

More work needs to be carried out to establish the limits of the hybrid's tolerances versus this species in UK. In damper mire habitats, the hybrid is also likely to occur, usually greatly outnumbering either species.

(See Andy Amplett's very clear note (
BSBI News, No. 119, p.37 (January 2012) download here. describing this species' habitats in Speyside, along with comments on the other two taxa.)

Enter the name for this tabbed section: NVC
The publication of NVC communities (Rodwell et al., British Plant Communities, Vol. 2, 1991) pre-dated the clarification of the three deergrass taxa, and some listings of 'Scirpus cespitosus' could possibly refer to this species, and many must include the hybrid.

The habitats associated with +/- calcareous mires (as in Upper Teesdale and Perthshire) fit nicely in
M10, especially M10b.

See Andy Amplett's very clear note (
BSBI News, No. 119 (January 2012) download here), describing this species' habitats in Speyside, along with comments on the other two taxa. He finds this species in 'lagg-zones', but he says: "I am confident that the primary habitat for this species in Abernethy Forest is M18 bog". North Pennine sites on deep blanket peat also probably fit here.

The 'lagg-zone' communities are tricky to categorise, and I have not successfully achieved this. The problem is that the actual sites of the plant are often over very limited areas indeed, and occur within extensive areas of different vegetation. There is thus no extensive areas of 'uniform' vegetation to work upon. Amphlett describes in Abernethy Forest such lagg sites in seepage areas located within species-rich heathland,
H16a.

As in all areas of field-botany: more work needed!

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