Nm- Phytol. (1983) 95. 153-157 ^ 53

THE IDENTITY AND ORIGINS OF PICEA ABIES(L.) KARSTEN FROM THE CHELFORDINTERSTADIAL (LATE PLEISTOCENE)

OF ENGLAND

By D. T. HOLYOAK

Quaternary Research Unit, Department of Botany, University of Reading,Reading RG6 2AS, UK

{Accepted 27 April 1983)

SUMMARY

Pollen and mscrofossils of Picea from the Ghetford Ititerstadia! {Early Devensian) of Englandare described. All leaves and cones were referred to P. abtes (L.) Karsten, and the unimodalsize distribution of pollen also suggests on!y this species was present. The fossil leaves are mostlysimilar to those of P. abies subspecies obmata (Ledeb ) HuJten, but the cones are intermediatebetween subspecies iihoiata and abies. Occurrence of forms approaching the north-eastEuropean subspecies obm^ata does not necessarih' imply immigration oi Ptcea into England fromthe east or north-east during the Early Devengian because similar intermediate forms also occurin the Alps.

I N T R O D L C T I O N

Tlie Chelford Interstadial of the Early Devensian is distinctive in the LatePleistocene of Britain mainly because of the plentiful representation of Picea. Incontrast the preceding Ipswichian Interglacial had only ver>- low frequencies ofPicea pollen (West, 1980).

The Chelford Interstadial deposits have been correlated with those of the BrorupInterstadia! of Denmark (Simpson and West, 1958). Occurrence of two Picea pollent 'pes has been reported from north-west European Brorup age deposits, and thesehave been referred to P. abies (L.) Karsten and P. omorikoides Weber (Andersen,1961; Zagwijn, 1961). PoUen from the Chelford Interstadial type site in Cheshirewas found however, to resemble that of P. abies (Birks, 1978). Leaves from depositscorrelated with the Chetford Interstadial at Beetley, Norfolk were identified asP. abies cf. subspecies obovata (Ledeb.) Hulten by Phillips (1976). Whitehead(1977) likewise identified five incomplete cones from Chelford as P. obotata Ledeb.rather than P. abies. Birks (1978) showed that Picea pollen from Chelford wassimilar in morphology' to his 'group B', the predominantly Scandinavian andRussian type of P. abies pollen (although this type was also found in one samplefrom Yugoslavia). Subspecies obovata is the form of P. abies native in north-easternEurope (Tutin et al., 1964). so on the basis of the occurrence of the Scandinaviantype of pollen and the macrofossils attributed to subspecies obovata, Birks {op. cit.)suggested that in the Early Devensian this subspecies had a larger range extendingwestwards to Britain.

This paper reports results of study of additional Picea pollen and macrofossilsof Chelford Interstadial age, from the t>pe site (Farm Wood Quarry, Chelford),Acre Nook Quarry close to the type site, and from Brimpton, Berkshire (Bryant,

«)28.546X/83/o9oiS3+05 S03.00/0 Q 1983 Thf Ne* Phrtologist

154 D. T . HOLVOAK

Holyoak and Moseley, in press), leading to a reappraisal of the direction from whichthese Picea may have reached Britain.

LEAVES

Phillips (1976) identified leaves from Beetley as P. abies cf. subspecies obotatabecause they were more robust than is usual in subspecies abies, and mostly hadmore rows of stomata. Leaves of subspecies obovata typicalJy have four stomatalrows on each of the two \ entral faces, and three on each dorsal face, compared totwo or three (ventral) and two (dorsal) in subspecies abies. A majority of the fossilleaves from Beetley had the larger numbers of stomatal rows characteristic ofsubspecies obovata, although some had fewer.

Table 1. Measurements of leaves of Picea abies

Picta abies ssp. abiesUppsala, Sweden (n = 20)'Suffolk (cultiv.) (n = 20)*Bedgeburj. V.K. (cultn.) (n = 50)

Ptcea abies ssp. obotataRussia (n = 20)*.•Mtai Mts (n = 20)«Finnish Lapland (n = 20)*N'E Finland (»i = 50)

Fossil leavesB«t!ey (n = 500)*Brimpton (n = 50)Acre Nook Quarry. Chelford (n = 50)Farm Wood Quarrv, Chelford. (n = 50)

Stomatal rows(one ventral face:one dorsal face)

3:2(3:2-2:1)2 :2 (3 :2 -2 : ) )3:2(3:2 2:1)

4:3(7:5 2:1)4:3(7 :5 2:1)4:3(5:4-3:3)4:3(6:4 2: t)

4:3(8:4 2:1)4:3(7 :6-2 :1)4:3(6:4-2:1)4:3(7:4-2:1)

Leaf width(mm)

0-7 (0 5 0-81(^9(()-8 1 1)0-8(0-7-1 1)

1-2(0-8 1-4)1-0(0-8 1-6)1 2(0-1* 1 6)1-1 (0-8 1-5)

!-0(0-6-l-9)1 3(0-8 1-5)1-1 (07-1-6)1-1 (0-8 16)

Leaf length(mm)

10(8-13)11 (9-13)11 (813)

13(11 16112(7 !5)11 (8 14)12(8 14)

10(7-14)10(7 13)11 (7-14)11 (6 14)

• Data from Phi]lip.s, 1976

Examination of 50 leaves from Brimpton (Sample 59J), 50 from Acre NoolQuarry, Chelford and 50 from Farm Wood Quarry, Chelford showed that thesalso most often had four rows of stomata on each ventral face and three on ead:dorsal face (Table 1). Numerous individual leaves in each of these three sampfehad fewer rows and some had more. Leaf width and length were very variable ireach sampJe; statistical treatment of measurements was avoided because a prevalenciof short stout leaves in at least the Brimpton sample might have been due to monfrequent breakage of long thin leaves. However, comparisons of the overlappinsranges of stomatal row numbers show that the Chelford and Brimpton leasamples resemble those from Beetley in suggesting more similarity to subspecieobovata than to subspecies abies.

CONES

Whitehead (1977) identified five partly incomplete Picea cones from Chelford asP. oboz-ata Ledeh. on the basis of the rounded cone scales. However, m.'observations show that the majority of cones from Chelford have damaged confscales. In samples of 99 cones from Farm Wood Quarry and c. 30 from Acre Nw'

Interstadial Picea abies 155

""^ ' " "''P '*^ '^'"'''' "*"•' subspccifs ahies/ohmata. Chelford Interstadial (Farmsuh ^'^'^- Chelford, Cheshire; Coll Dr. P Worsley). t «o views of same cone, (b) Ptcea ab,esK I M ' , ' " ' ' "*"• ' "< ' • Chelford Interstadial (.Acre .Nook Quarry. Chelford, Cheshire- Coil Dr(Loiu., ^ **• "*'" ' " * ' "f '^^ ""'"'• ™"'" f" '' <''> ^"•'•'' " ' " " subspecies ahmata. modernQ()if m 7 * ^ " ' ' " ' ' ^ " " "^ ' '•'^'^'*• ^ ' '^"'•""' ' ' ' '^ '• '•"^"""' ' P«'»"dS. (e) Aff« a6,« aubspccicsKewi m P™ ''^"''"•^"•'' «' Bedgehury National Pinetum, England: per Royal Botanic Gardens,'0 (i) P " " s"hspecies abies. modern (Haute-Savoie, France: Coll. D T. Holyoak). (g)

Kea omortka. modern (cultivated at Bedgebury National Pinetum, England: per RoyalBotanic Gardens. Kew).

156 D. T. HOLYOAK

Quarr\' the small fraction of cone scales that had survived completely intact werefound to be less rounded than in typical subspecies obovata [Fig. l(a), (b) cf. (c),(d)], but instead to approach some subspecies abtes in form of the cone scales [cj.Fig.' 1(0]- Furthermore, the intact cones from Chelford were larger than is usualin many populations (not all) of subspecies abies, which itself usually has largercones than the 6 to 8 cm typical of subspecies obovata.

POLLEN

Picea pollen from Early Weichsehan interstadial deposits in north-western Europehas been found to include both P. abies type and smaller grains that Andersen(1961) and Zagwijn (1961) attributed to P. omorikoides Weber. The latter speciesis based on Pleistocene fossils from Germany; the very detailed original description(Weber, 1898) shows that it is similar to P. omorika (Pancic) Purkyne, which isknown as a native tree only in central Yugoslavia (Jalas and Suominen, 1973), andIt may be most simply regarded as conspecific with that species. A leaf tentativelyattributed to P. omorika has been reported from the Pastonian of Norfolk (Wilson,1973), but there appears to be no Late Pleistocene record of macrofossils fromnorth-western Europe.

Measurements of Picea pollen from Brimpton (biozone Br-C) and the ChelfordInterstadial type site show unimodal size distributions and give no indication thatP. omorika might bave occurred (Fig. 2). Cones of P. omorika [Fig. l(g) to (j)] andleaves (Weber, 1898, Taf. XI) are distinctive and nothing resembling them wasfound in either the Chelford or Brimpton samples.

20-

0 -20 r

lOf

nID) n

16 20 24 28 32 36 40Micrometer l ines

Fig. 2. Measurements of pollen (height of air-sacs) of Picea sp. (a) Brimpton. n = 60; (h) Cheifordn = 148; (cj modem P. at)ies (Norway), n = 176; <d) modem P. omorika (Yugoslavia), n = 80.

DISCUSSION AND CONCLUSIONS

The P. abies from the Chelford Interstadial thus appears to have had leaves mosti>similar to those of subspecies obovata, cones intermediate between subspeci«obovata and abies, and pollen (fide Birks, 1978) of a predominantly Scandinaviatype. However, although subspecies obovata is the north-east European foioccurring mainly in western Siberia (USSR), it would be premature to

Interstadial Picea abies 157

this form colonized Britain from the east or north-east during the Early Devensjan.Forms more or less intermediate between subspecies abies and subspecies obovataare well known in the Alps [Tutin et al., 1964; Weihe, 1972; Fig. 1 (f)] and Poland^Srodon, 1967), as well as in Fennoscandia. In their combination of leaf, cone andpollen characters the Cheiford Interstadial Picea do not correspond closely to anyof these living intermediate popuiations. However, some of the morphologicalcharacters of the leaves, cones or pollen might be affected primarily by localenvironmental factors (e.g. daylength, humidity, temperature) rather than beingunder simple genetic control. Consequently, immigration oi Picea in the ChelfordInterstadial might have been from the north-east, east or south-east, and thecharacteristics of fossil pollen, leaves and cones may not allow discriminationbetween these different origins.

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