Deschampsia cespitosa subsp. parviflora (Poaceae) - an overlooked woodland grass

Abstract

Deschampsia cespitosa (L.) P. Beauv. subsp. parviflora (Thuill.) Dumort was, to British and Irish botanists, a little known taxon prior to1988, and current distribution mapping shows a marked geographical recording bias. It is confirmed as being primarily a woodland taxon, at low altitudes; modal mean altitude 50-75 m AOD, with 97% of locations at ≤300 m AOD. A combination of woodland or shaded habitat, bright green narrow leaves, and delicate panicle, with small spikelets, is suggestive of subsp. parviflora. In combination, degree of leaf blade scabridity on the adaxial surface, appearance of papillae on flat surfaces of adaxial ridges of the leaf, and spikelet length, provide the most reliable means of distinguishing this subspecies from subsp. cespitosa. There is no reason to suspect that subsp. parviflora is increasing, rather it had previously been overlooked.

Full text

117
British & Irish Botany
1(2): 117-127, 2019
Deschampsia cespitosa
subsp
. parviflora
(Poaceae) - an
under-recorded woodland grass
Andy Amphlett*
Grantown on Spey, Scotland
*Corresponding author: Andy Amphlett, email: amphlett1958@gmail.com
This pdf constitutes the Version of Record published on 21st May 2019
Abstract
Deschampsia cespitosa
(L.) P. Beauv. subsp
. parviflora
(Thuill.) Dumort was, to
British and Irish botanists, a little known taxon prior to1988, and current distribution
mapping shows a marked geographical recording bias. It is confirmed as being
primarily a woodland taxon, at low altitudes; modal mean altitude 50-75 m AOD,
with 97% of locations at ≤300 m AOD. A combination of woodland or shaded
habitat, bright green narrow leaves, and delicate panicle, with small spikelets, is
suggestive of subsp
. parviflora
. In combination, degree of leaf blade scabridity on
the adaxial surface, appearance of papillae on flat surfaces of adaxial ridges of the
leaf, and spikelet length, provide the most reliable means of distinguishing this
subspecies from subsp.
cespitosa
. There is no reason to suspect that subsp
.
parviflora
is increasing, rather it had previously been overlooked.
Key Words
Identification; recording bias; altitudinal range; habitat; tufted hair-grass.
Introduction
In British and Irish Floras,
Deschampsia cespitosa
(L.) P. Beauv.
subsp
. parviflora
(Thuill.) Dumort, was first mentioned (at varietal level) in the first edition of the
Flora of the British Isles (Clapham et al 1952). However, it was not until the more
detailed account in the Plant Crib (McAllister 1988), that this taxon became more
widely known, and there was a rapid increase in recording, as documented by
records in the Distribution Database maintained by the Botanical Society of Britain
and Ireland (https://database.bsbi.org/), henceforth referred to as the ‘BSBI
database’ (Fig. 1).
Although aware of subsp.
parviflora
, it was not until 2015 that I first found
distinctive examples of this subspecies, at two sites in Derbyshire (v.c.57). This
encouraged me to follow up an old Easterness (v.c.96) record in 2016, but without
success. On 1st June 2017, accompanied by Linda Henderson, I visited an area of
woodland at Ferness in the valley of the River Findhorn (v.c.96) to see a newly
found population of Bird's-nest Orchid
Neottia nidus-avis
. Almost as soon as we
entered the wood, we came across tens of small tussocks of a non-flowering
graminoid plant, with bright grass-green, narrow leaves (Fig. 2), that I initially took
to be Remote Sedge
Carex remota
, a rather local species in north Scotland. On
closer examination of the leaves, and pulling apart an unopened inflorescence, I

118
realised the tussocks were of
D. cespitosa
. I returned on 11th June, when several
tussocks had ± open panicles, to collect specimens for closer examination,
confirming that the plants were indeed
D. cespitosa
subsp.
parviflora
.
Figure 1.
Deschampsia cespitosa
subsp.
parviflora
. Number of hectads per decade
in GB and Ireland, based on records in the BSBI database.
Figure 2.
Deschampsia cespitosa
subsp
. parviflora
: Ferness (River Findhorn)
(v.c.96) June 2017.
0
50
100
150
200
-1929
1930-1939
1940-1949
1950-1959
1960-1969
1970-1979
1980-1989
1990-1999
2000-2009
2010-2019
Hectads

119
During June 2017, I found additional stands of
D. cespitosa
subsp.
parviflora
at three more locations in the River Findhorn valley, and beside a tributary of this
river (Fig. 3). I also found plants at a single site in Glen Affric (v.c.96). In July 2017,
I found plants at an additional site in v.c.57 and in Staffordshire (v.c.39).
Figure 3. Deschampsia cespitosa
subsp
. parviflora
: Tomnarroch Burn (v.c.96)
June 2017.
Distribution
On current knowledge, within the BSBI recording area,
D. cespitosa
subsp.
parviflora
is almost restricted to England, Wales and Scotland, which account for 98% of the
recorded hectad range (Table 1). There is a single record from the Isle of Man
(v.c.71) collected in 1950. There are no records from the Channel Isles (v.c.113).
In Ireland, there are un-localised 1967 / 1968 records from woodland in Co.
Clare (H09), North Kerry (H02) and Co. Cavan (H30), (Farragher 1969); these are
not included in Table 1. The first localised record was in 1999 (Dines 2000) in a
'wonderful fragment of deciduous woodland south of Easky' (Co. Sligo). In N.
Ireland, John Harron reported this subspecies from Co. Armagh (H37) in 2005, and
in four hectads in Co. Antrim (H39) between 2006 and 2016.
In Scotland, excluding the author's recent finds, there are 41 distinct records,
from 37 locations, in 34 hectads, in 14 vice-counties. There are concentrations of

120
records in Fife (v.c.85) 11 hectads, and in Ayrshire (v.c.75) 5 hectads. North of the
central belt, all but one of the post-1999 records are by the author or George
Ballantyne.
Table 1.
Deschampsia cespitosa
subsp.
parviflora
. Number of hectads up to and
post-1999. Based on records in the BSBI database.
Pre-
2000
2000-
Total
England
194
249
352
Wales
29
28
49
Scotland
29
9
36
N. Ireland
0
5
5
Ireland
1
0
1
Isle of Man
1
0
1
Figure 4.
Deschampsia cespitosa
subsp.
parviflora
hectad distribution map. (From
BSBI database 14/2/2019). Black (post-1999), red (pre-2000).
The hectad distribution map (Fig. 4), is strongly suggestive of a geographical
recording bias, with marked concentrations of records in (inter alia) Worcestershire
(v.c.37), Denbighshire (v.c.50), Derbyshire (v.c.57), Cheshire (v.c.58), and South
and West Lancashire (v.c.s 59, 60). The recording bias is especially pronounced
post-1999.

121
Habitat
Floras and other published accounts broadly agree on the habitat within which this
subspecies occurs: woodland on heavy soils (Clapham et al 1987); woods & shady
hedgerows (Stace 2019); woods & shady places, especially on heavy soils (Sell &
Murrell 1996); lowland woods on heavy soils (Cope and Gray 2009); lowland
woodland (Parnell and Curtis 2012); damp shady places on heavy soils (Hubbard
1984); shaded places in ancient woodland (McAllister 1998). Of the 1550 records of
D. cespitosa
subsp.
parviflora
on the BSBI database (DDb) (at February 2019), 150
records have some indication of habitat. Of these 150 records, 130 (87%) refer to
woodland or shade. Habitat and associated species of populations of
D. cespitosa
subsp.
parviflora
found by the author in 2017, are summarised in Table 2.
Table 2. Habitat and associated species of populations of
D. cespitosa
subsp.
parviflora
found by the author in 2017 in v.c.s 39, 57 and 96.
VC
Locality
Grid
reference
Habitat & associated species
39
Coldwall Bridge
(S. of)
SK14874958
On bank by track under
Acer
pseudoplatanus
,
Crataegus monogyna
,
Fraxinus excelsior
and
Ulmus glabra
,
with
Circaea lutetiana
and
Mercurialis
perennis
.
39
Coldwall Bridge
(SW of)
SK14844963
Bank by track under
C. monogyna
&
Rosa sp
..
39
Coldwall Bridge
(SE of)
SK15224959
Under
A. pseudoplatanus & U. glabra
,
with
Dryopteris filix-mas
,
Epilobium
montanum
,
Galium odoratum
,
Geranium
robertianum
,
Hypericum hirsutum
,
M.
perennis
,
Rubus fruticosus agg
..
57
Miller's Dale
SK138731
In north facing woodland, with Sanicula
europaea.
57
Carsington Water:
Shiningford Farm
(SE of)
SK24635226
In woodland by FP.
57
Carsington Water:
Sheepwash Car
Park (NE of)
SK25035297
In woodland with
Bromopsis ramosa
,
Dryopteris dilatata
,
F. excelsior
,
Geum
urbanum
,
R. fruticosus agg
.,
Sambucus
nigra
,
Urtica dioica
.
57
Via Gellia
SK265565
In north facing woodland, with Melica
uniflora.
96
Allt na Ciche
(W. side of)
NH12091922
Under
Alnus glutinosa
, close to burn.
96
River Findhorn (S.
side): Dulsie
Bridge (upstream
of)
NH92664042
On steep flushed slope under
A.
glutinosa
. Associate species incl.
Veronica montana
,
Circaea x intermedia
,
Stellaria holostea
,
Carex remota
.
Stellaria
nemorum
a few metres away.

122
96
River Findhorn (SE
side): Dulsie
Bridge (upstream
of)
NH92844056
NH92844057
Flushed slope in woodland above river.
Associate species incl.
Carex laevigata
,
C. remota
,
Crepis paludosa
. Canopy of
A.
glutinosa
&
Salix caprea
.
96
River Findhorn (S.
side): Dulsie
Bridge (upstream
of)
NH92674041
On grassy slope, open area in woodland,
above river. Associate species incl.
Oreopteris limbosperma
,
S. holostea
,
Holcus mollis
,
Rumex acetosa
.
96
Tomnarroch Burn
(E. of)
NH96214406
In flushed
A. glutinosa
woodland on
slope near burn.
96
Ferness (W. of)
NH96174486
In damp woodland. Associated species
Ajuga reptans
,
Ranunculus repens
,
Veronica chamaedrys
, with occasional
Lysimachia nemorum
. Canopy of
Betula
pubescens
&
F. excelsior
.
96
Cairnglass (SW of)
NH96044666
NH96064665
On flushed slope under
A. glutinosa
.
Associate species incl.
A. reptans
,
Blechnum spicant
,
Caltha palustris, C.
laevigata
,
Carex paniculata
,
Chrysosplenium oppositifolium
,
Dryopteris affinis agg
.,
D. dilatata
,
G.
robertianum
,
H. mollis
,
Juncus effusus
,
Oxalis acetosella
,
R. acetosa
.
Altitudinal range
There are records of
D. cespitosa
subsp.
parviflora
on the BSBI database from 1057
unique grid references, at tetrad or better precision. Mean altitude for each grid cell
was calculated and plotted against the number of unique grid references (Fig. 5).
Figure 5.
Deschampsia cespitosa
subsp.
parviflora
. Number of unique location
grid references x mean grid cell altitude (25 m class intervals).
0
20
40
60
80
100
120
140
160
180
<25
25-50
50-75
75-100
100-125
125-150
150-175
175-200
200-225
225-250
250-275
275-300
300-325
325-350
350-375
375-400
400-425
425-450
450-475
475-500
Number of unique grid references
Altitude (m)

123
The modal mean grid cell altitude is 50-75 m AOD, and 97% of locations are ≤300
m. A similar analysis was undertaken for all records of
D. cespitosa
on the BSBI
database, excluding those of subsp.
parviflora
; 110,081 unique grid references.
Compared to records only identified to species level, or ascribed explicitly to other
infraspecific taxa, subsp.
parviflora
is proportionately more frequent in the altitude
ranges 25-200 m and 250-275 m. Nearly all localised records of subsp.
parviflora
>300 m AOD are in Wales, the highest reported being at c.365 m AOD at Craig y
Moch, Denbighshire (v.c.50).
In the broad sense,
D. cespitosa
reaches a maximum altitude of 1335 m AOD
on Ben Nevis, West Inverness-shire (v.c.97). While many of the highest altitude
records are of
D. cespitosa
subsp.
alpina
(Alpine Hair-grass),
D. cespitosa
subsp.
cespitosa
is found to at least 1000 m AOD in the Cairngorm Mountains, and probably
higher.
Identification
A number of features have been reported to distinguish
D. cespitosa
subsp.
parviflora
from subsp.
cespitosa
(Table 3). These are discussed in turn, below.
Chiapella and Probatova (2003) put forward two discriminatory characters
additional to those listed in Table 3. Awn length: exceeding (or not) the top of their
lemmas in subsp.
parviflora,
cf not exceeding the top of their lemmas in subsp
.
cespitosa
. Spikelets per panicle: 100-150 in subsp.
parviflora
cf <100 in subsp
.
cespitosa
. I have not investigated either of these, but it should be noted that
D.
cespitosa
is extremely variable (Cope & Gray 2009).
A combination of woodland or shaded habitat, bright green leaf colour, narrow
leaves and delicate panicle, with small spikelets, is suggestive of subsp
. parviflora
. In
combination, leaf blade scabridity on the adaxial surface, appearance of papillae on
flat surfaces of adaxial ridges of the leaf, and (accurately measured) spikelet length,
provide the most reliable means of distinguishing the two subspecies.
Habitat
Subspecies
parviflora
is very strongly associated with shaded habitats, principally
woodland. I have not found it in fully open habitats. However, in itself, that
association is insufficient to identify this taxon.
Leaf colour
Bright grass-green (Figs 2 and 3), cf the bluish, mid or dark green of subsp.
cespitosa
. This qualitative difference is consistent in the plants I have examined.
Leaf width
Viewing a whole tussock, the leaves of subsp.
parviflora
do tend to appear narrower
than those of subsp.
cespitosa
. However, I failed to find a practical and unbiased
method of measuring leaf widths; there is so much variation within a tussock. It is
best considered a jizz feature, markedly narrow leaves being possibly suggestive of
subsp.
parviflora
.
Leaf blade scabridity on the adaxial surface
The ridges on the adaxial (upper) surface of leaves of subsp.
cespitosa
are armed
with forward pointing spines. Hold a leaf firmly between finger and thumb of one

124
hand; with your other hand squeeze the leaf blade between finger and the other
thumb, and try to move your hand towards the base of the leaf. It will be difficult or
impossible to slide your finger and thumb along the leaf in subsp.
cespitosa
; the leaf
is likely to snap in fresh material. If you do the same with a leaf of subsp.
parviflora
your finger and thumb will slide, relatively easily along the leaf, though with some
resistance. Test this with several leaves.
D. cespitosa
subsp.
parviflora
D. cespitosa
subsp.
cespitosa
Habitat 2, 3
Woodland; shade
tolerant plant
More open habitats
Leaf colour 1, 3
Bright green
Bluish-green; medium to
dark green
Leaf width 4
Narrower than subsp.
cespitosa
Wider than subsp.
parviflora
Leaf blade scabridity on the
adaxial surface 1, 3
Less scabrid than
subsp.
cespitosa
Coarsely scabrid
Papillae ('spines' sensu
McAllister) on flat surface of
adaxial ridges of leaf 1, 3
Appearing as light or
yellowish green
translucent spots (in
living material)
Appearing as more opaque
whitish green spots
Spikelet length (mean of 10
published ranges; original
values at 0.5 mm precision) 2
2.1 - 3.3 mm
3.4 - 5.5 mm
Spikelet length (range of
spikelet length
measurements by author
(this paper); 0.1 mm
precision 3
2.6 - 3.8 mm
3.8 - 5.6 mm
Hairs at base of rhachilla 1, 6
Shorter than rhachilla,
Usually longer than
rhachilla
Hairs on rhachilla 1
Less than half rhachilla
length
More than half rhachilla
length
Spikelet colour 5
Pale green
Green, dark green or
violaceous, or a mix
Table 3.
Deschampsia cespitosa
. Distinguishing features of subspecies
parviflora
and
cespitosa
. Sources: 1 McAllister (1998); 2 Clapham et al (1987), Stace (2019),
Sell and Murrell (1996), Rose (1989), Cope & Gray (2009), Parnell & Curtis
(2012), Hubbard (1984), McAllister (1998), Chiapella and Probatova (2003); 3
Amphlett (this paper), 4 Cope and Gray (2009); 5 Chiapella and Probatova (2003);
6 Stace (2019).
Papillae on flat surface of adaxial ridges of leaf
The flat surfaces, either side of the ridges on the adaxial surface of leaves, support
low rounded papillae. McAllister (1998) refers to these structures as 'spines', but that
is a misleading description. At x10 magnification, they resemble stomata (or a

125
structure surrounding the stomata). However, at x30 they are revealed as papillae.
The appearance of these papillae differs between the two subspecies, but to see this
requires good illumination and a good quality hand lens. It is best to examine leaves
under a low power stereo microscope, ensuring that the angle of incident
illumination is kept constant. The appearance of the papillae is best assessed under
medium intensity illumination. The papillae of subsp.
parviflora
are light or yellowish
green, appearing as glistening, translucent dots, c.0.03 mm in diameter, while those
of subsp.
cespitosa
are more easily seen, being larger (c.0.1 - 0.2 mm), and a more
opaque whitish green.
Spikelet length
All published accounts refer to a difference in spikelet length. Nine Floras and other
published accounts give mean minimum and maximum spikelet lengths (extreme
values in brackets) of subsp.
parviflora
(2.0) 2.1-3.3 (3.5) mm and subsp.
cespitosa
(3.0) 3.5-5.7 (6.0) mm. The original values are only given to 0.5 mm precision.
To investigate this character further, I collected single, whole panicles, from 79
tussocks of
D. cespitosa
. Based on leaf colour, leaf blade scabridity on the adaxial
surface, and appearance of papillae on the flat surface of adaxial ridges of the
leaves, they were allocated to one or other of the subspecies. 42 tussocks were of
subsp.
parviflora
(21 from Scotland (v.c.96) and 21 from England (v.c.s 39 and 57),
and 37 tussocks were of subsp.
cespitosa
from Scotland (v.c.s 95 and 96). Spikelet
lengths within a panicle are variable, and an attempt was made to collect an
unbiased sample of lengths per panicle, by measuring spikelets from all parts of
each panicle. Ten spikelets were measured per panicle, and the mean length
calculated. Lengths were measured to 0.1 mm precision, using a stereo microscope
with a calibrated eyepiece graticule. Spikelet length was defined as the straight-line
distance from the lowest point of green tissue at the base of the lowest glume to the
tip of the hyaline apex of the apical lemma. It is very difficult to accurately measure
spikelet lengths in the field. The position of the hyaline apices of the lemmas are
easily misjudged, and accurate measurements obtained under a microscope are
usually longer than those estimated in the field.
Mean spikelet lengths are shown in Figure 6. Although Cope and Gray (2009)
stated that variation in this character is continuous, on the basis of my results it is
markedly bimodal. Ranges of mean spikelet lengths in the plants sampled were
subsp.
parviflora
2.6 - 3.8 mm and subsp.
cespitosa
3.8 - 5.6 mm. The sampled
Scottish plants of subsp.
parviflora
had slightly longer spikelets than the sampled
English plants, median 3.4 cf 3.1 mm (p<0.05, Mann Whitney U-test). Insufficient
separate populations have been sampled to judge if this difference is of biological
interest. That plants differentiated on other morphological grounds differed in
spikelet length, adds weight to the distinctiveness of the two subspecies.
Apparently intermediate forms do occur. Two examples measured had mean
spikelet lengths of 3.4 and 3.7 mm. Once I had found subsp.
parviflora
in v.c.96,
and gained some appreciation of its preferred habitat, my searching and sampling
may have been biased to finding 'good' examples of this subspecies, and I may have
avoided habitats where plants were less distinctive. I have looked for subsp.
parviflora
under
A. glutinosa
along the banks of the River Spey in Moray v.c.95 and
though I have found plants with something of the appearance of this subspecies,

126
none have (to date) been convincing. These plants are not included in the above
measurements.
Figure 6. Mean spikelet length,
Deschampsia cespitosa
subsp.
parviflora
cf subsp.
cespitosa
.
Rhachilla hairs
The relative length of hairs at the base of, and on the rhachilla, I found an
impractical character. It is difficult to dissect individual spikelets, and there remains
the problem of classifying hairs that are ± the same length as the supposedly
discriminating character.
Spikelet colour
Spikelets of subsp.
parviflora
are pale green, and those of subsp.
cespitosa
are often
violaceous, but I have not investigated if the colour difference is reliably consistent.
It would, anyway, only be applicable to fresh material.
Conclusion
Deschampsia cespitosa
subsp.
parviflora
is a distinct taxon, which can be
distinguished in the great majority of cases from subsp
.
cespitosa
by a combination
of quantitative and qualitative characters. The taxon was not recognised from a
European perspective by Clarke (1980), but has been included in Floras of the British
Isles since Clapham et al (1952), and was accepted by Chiapella (2000) in his review
of
D. cespitosa
in central and northern Europe.
Of 441 hectads in which subsp.
parviflora
has been recorded in Britain and
Ireland, it was first recorded in 381 hectads (86%) post-1986. Records from several
vice-counties where subsp.
parviflora
is now considered to be fairly frequent, show a
marked increase more recently: Derbyshire (v.c.57) from 1997; West Lancashire
(v.c.60) from 1998; Cheshire (v.c.58) from 2000; and Worcestershire (v.c.37) from
0
1
2
3
4
5
6
7
8
2.5
2.7
2.9
3.1
3.3
3.5
3.7
3.9
4.1
4.3
4.5
4.7
4.9
5.1
5.3
5.5
5.7
5.9
Frequency
Mean spikelet length (mm)
parviflora
cespitosa

127
2003. There is no reason to suspect that this subspecies is increasing; rather that it
had previously been overlooked.
In the course of general botanical recording in north Scotland over the last two
years (mainly in v.c.96), of 135 locations where I noted
D. cespitosa
, <5%
supported subsp.
parviflora
. Hence in northern Scotland, subsp.
cespitosa
is by far
the commoner taxon.
References
Chiapella, J. 2000. The
Deschampsia cespitosa
complex in central and northern
Europe: a morphological analysis.
Botanical Journal of the Linnean Society
,
134: 495-512.
Chiapella, J. & Probatova, N.S. 2003. The
Deschampsia cespitosa
complex (
Poaceae:
Aveneae
) with special reference to Russia.
Botanical Journal of the Linnean
Society
, 142: 213–228.
Clapham, A.R., Tutin, T.G. & Warburg, E.F. 1952.
Flora of the British Isles
.
Cambridge: Cambridge University Press.
Clapham, A.R., Tutin, T.G. & Moore, D.N. 1987.
Flora of the British Isles
. Cambridge:
Cambridge University Press.
Clarke, G.C.S. 1980.
Deschampsia
account, In Tutin, T.G., Heywood, V.H., Burges,
N.A., Moore, D.M., Valentine, D.H., Walters, S.M. & Webb, D.A.,
Flora
Europaea
, Volume 5. Cambridge: Cambridge University Press.
Cope, T. & Gray, A. 2009.
Grasses of the British Isles
. BSBI: London.
Dines, T. 2000. A little more Atlas recording in Ireland. BSBI News 84: 78-79.
Farragher, M.A. 1969.
Deschampsia caespitosa
(L.) Beauv.
var parviflora
(Thuill.)
Coss. and Germ.
The Irish Naturalists' Journal
: 16, No. 6, p. 177.
Hubbard, C.E. 1984.
Grasses. A guide to their Structure, Identification, Uses and
Distribution in the British Isles
. London: Penguin.
McAllister, H. 1988.
Deschampsia cespitosa
account, In Rich, T.C.G. & Rich, M.D.B.,
Plant Crib
. London: BSBI.
McAllister, H. 1998.
Deschampsia cespitosa
account, In Rich, T.C.G. & Jermy, A.C.,
Plant Crib 1998
. London: BSBI.
Parnell, J. & Curtis, T. 2012.
Webb's An Irish Flora
. Cork: Cork University Press.
Preston, C.D., Pearman, D.A. & Dines, T.D. 2002.
New Atlas of the British and Irish
Flora
. Oxford: Oxford University Press.
Rose, F. 1989.
Colour Identification Guide to the Grasses, Sedges, Rushes and Ferns
of the British Isles and north-western Europe
. London: Viking.
Stace, C.A. 2019.
New Flora of the British Isles
. 4th ed. Middlewood Green: C & M
Floristics.
Sell, P. and Murrell, G. 1996.
Flora of Great Britain and Ireland
. Volume 5.
Cambridge: Cambridge University Press.
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Commons Attribution 4.0 International Public License.
ISSN: 2632-4970
https://doi.org/10.33928/bib.2019.01.117