Includes pollen of two distinct types: see Kalis (1980).
Refers to species of the Papaver radicatum group, widespread in
the arctic. None are native to the British Isles today, but the
pollen may be found in full-glacial and Devensian late-glacial
deposits.
This is the pollen type variously given as 'Corylus/Myrica' or
'Coryloid'. In western Europe, it may be possible to identify
some grains of Myrica gale, but the ranges of variation of pollen
of the two species in the type have considerable overlap. I
suggest using the type nomenclature for most identifications, and
separately using 'Myrica gale' for those grains that are
certainly derived from that species. In this way, a minimum curve
for Myrica gale can be achieved while the bulk of the grains will
be included in a type whose name reflects the likely taxonomic
origin of most of them.
Pollen of the Caryophyllaceae falls into two morphological
categories. Grains of Spergula-type are tri- or hexa-colpate,
while the others are periporate. Care needs to be taken that a
category used for undifferentiated Caryophyllaceae periporate
grains does not also imply the possibility that Spergula-type
could be represented. Holosteum umbellatum may also be native in
the British Isles: its pollen is within Cerastium-type. Stellaria
crassifolia and Silene furcata have occurred as macrofossils in
Quaternary cold-stage sediments: I have not seen pollen or
descriptions of the pollen of either. Birks (1973) has different
pollen types from those listed here.
See van Leeuwen et al. (1988). The types used here for Rumex
and Oxyria digyna follow Moore et al. (1989) more closely, but
there is some overlap between types because of morphological
variability of the grains.
See Turner & Blackmore (1984). Both native genera in the
Plumbaginaceae have dimorphic pollen. Type-A pollen can be
identified to generic level on morphological criteria, but not
Type-B (Moore et al. 1991). In SDQR reference material, sizes of
Type-B grains in Limonium overlap too much with the size of Type-B
Armeria maritima pollen to enable separation on size criteria
(in silicone oil, at least). Grains should therefore be
identified to either family or generic level, as appropriate for
the type concerned.
Moore et al. (1991) separate the Brassicaceae into two groups
on the basis of size of lumina. There is certainly considerable
variation in size between species, but also within species
depending on factors that include mounting medium. Species of
several genera can fall into either group. Taking these factors
together, there is little useful purpose in attempting to
separate fossil material into these groups.
All native taxa of the subfamilies Prunoideae and Maloideae:
this is a rather heterogenous group, and some distinctions are
probably possible, especially for Sorbus aucuparia and Prunus
padus (Faegri & Iversen 1989; Moore et al. 1991). However,
available reference material is varied between collections of the
same species, and I am uncertain about the validity of most
smaller divisions.
See Clarke & Jones (1980c). Note that pollen of Acer
monspessulanum (found as macrofossils in late Quaternary warm-
stages), A. platanoides, and A. pseudoplatanus (both introduced
to the British Isles in the late-Holocene) is indistinguishable
from A. campestre. These types are grouped by Moore et al. (1989)
as Acer campestre-type.
The Asteraceae has been traditionally divided by
palynologists into two broad categories: 'Tubuliflorae', for
tricolporate echinate grains, and 'Liguliflorae' for fenestrate
echinate grains. This separation does not, however, completely
cover the family. Asteraceae are divided into two subfamilies,
Lactucoideae and Asteroideae. The Lactucoideae are divided into
tribes, of which two, Cardueae and Lactuceae, have members in the
native flora of the British Isles. All Lactuceae have fenstrate
echinate grains, so this name is available for any grains of this
type that cannot be identified more precisely. I suspect that it
may be possible to distinguish pollen of the tribe Cardueae and
the subfamily Asteroideae routinely in even damaged material (but
I have not checked yet). Accordingly, I suggest that the two old
terms be replaced by three newer ones (Cardueae, Lactuceae, and
Asteroideae) for grains recognisable as being within these types.
If there are grains where it is not possible to see whether they
are Cardueae or Asteroideae, the best recourse might be to
combine the names: 'Cardueae / Asteroideae'. The only alternative
is to invent an informal name that cuts across the taxonomic
hierarchy. See Blackmore (1984) for distinctions within the
Lactuceae.