New records of fossil conifers from Suffolk

N E W RECORDS OF FOSSIL CONIFERS FROM

SUFFOLK

HUGH LANCE PEARSON

T h e megafossil plants of pre-Pleistocene age in Suffolk have b e e n reviewed ( P e a r s o n , 1987). H o w e v e r , examination of t h e Palaeontology collection at t h e British M u s e u m ( N a t u r a l History) has revealed a n u m b e r of undescribed a d d i t i o n s to t h e Suffolk p a l a e o f l o r a . T h e following are descriptions of s o m e of t h e s e s p e c i m e n s , which r e p r e s e n t conifers. I include only brief, initial a c c o u n t s of their p r o v e n a n c e , a n a t o m y and t a x o n o m i c affinities, leaving m o r e detailed structural investigations and t a x o n o m i c c o m p a r i s o n s for a s u b s e q u e n t article. i) Cretaceous wood from Botesdale In July 1865, a f r a g m e n t of silicified w o o d measuring a p p r o x i m a t e l y 5 3 m m x 2 3 m m x 2 m m was discovered e m b e d d e d in a flint n o d u l e f r o m the U p p e r C h a l k at B o t e s d a l e (See A p p e n d i x ) . A s yet, no microscopic p r e p a r a tions of this s p e c i m e n have b e e n m a d e , but it shows both transversely and longitudinally split facets for h a n d lens inspection. T h e relative uniformity in cell d i a m e t e r a n d s h a p e strongly suggests affinity with a c o n i f e r o u s family.

H o w e v e r , until m o r e detailed o b s e r v a t i o n s a r e m a d e , relations of this w o o d with certain flowering plants or with the m a i d e n h a i r trees ( G i n k g i n a c e a e ) c a n n o t b e ruled o u t .

N o t h w i t h s t a n d i n g its presently uncertain systematic position, this w o o d is r e m a r k a b l e in b e i n g t h e oldest fossil plant (i.e. f r o m t h e S e n o n i a n Stage of t h e U p p e r C r e t a c e o u s P e r i o d ) yet r e c o r d e d f r o m Suffolk ( P e a r s o n , 1987).

C o n i f e r o u s w o o d is t h e most f r e q u e n t kind of megafossil plant to b e f o u n d in t h e C h a l k of Britain, but it is n e v e r a b u n d a n t as such and little research o n it has b e e n p u b l i s h e d . ii) A conifer from Clay don - C e d r o x y l o n sp.

This single s p e c i m e n is r e p r e s e n t e d by f o u r microscope slides of thin sections (See A p p e n d i x ) . In c o m m o n with all c o n i f e r o u s w o o d s , it is homoxylic, i.e. lacking in xylem vessels or ' p o r e s ' . Similarly, most of t h e vascular rays are u n i s e r i a t e , rarely biseriate, b u t they may be u p to 36 cells high or d e e p .

B o r d e r e d pitting is p r e s e n t on t h e radial walls of t h e tracheids a n d rarely on their tangential walls. N o tori, crassulae (rims of Sanio), or tertiary wall d e p o s i t s (helices) a r e visible, and the vascular rays are c o m p o s e d of p a r e n c h y m a t o u s cells only in which n o pitting is evident. Distinct growth rings a r e a p p a r e n t , ranging b e t w e e n a b o u t l - 6 m m and 5-5mm in width. N o primary xylem, or leaf traces a r e p r e s e n t . T h e d e g r e e of c u r v a t u r e in t h e growth rings w o u l d indicate t h a t this s p e c i m e n was p r o b a b l y p a r t of a small b r a n c h of a m a t u r e t r e e or a m a j o r stem of a sapling. N o extraxylary tissues a r e p r e s e r v e d h e r e . T h e s e a n a t o m i c a l characters generally a g r e e with S e w a r d ' s (1919) a c c o u n t of t h e c o n i f e r w o o d f o r m - g e n u s Cedroxylon K r a u s . T h e precise site of origin at C l a y d o n , a n d hence its age, are not clearly d e f i n e d . T h e U p p e r C h a l k a n d Pleistocene strata a r e the m a j o r o u t c r o p p i n g rocks at C l a y d o n

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(Chatwin, 1961; fig. 28). However, deposits of both Palaeogene (viz.

Palaeocene Thanet Beds and Eocene London Clay) and possibly Neogene (viz. Newbournian Red Crag, taken by some to be Pliocene, West, 1977) age occur around Claydon. iii) Coniferous wood from the Red Crag at Waldringfield Three slides of homoxylic wood from the Red Crag were examined (see Appendix). The colour and mode of preservation of these specimens (which apparently do not come from the same original block) compare very closely with the large number of woods obtained from the Red Crag at Waldringfield. However, the quality of anatomical details preserved in each of these woods is rather poor, making their identification very difficult. Since they are homoxylic, however, it is reasonable to assume they are coniferous, given the rarity of angiospermous wood lacking vessels. No classification to family or genus or identification for these woods can be given here in view of their lack of sufficient structural detail. iv) A conifer from Ipswich Two microscope slides of a homoxylic wood from the Red Crag of an unspecified locality in Ipswich were examined (see Appendix). The quality of this specimen calls for the same comments as apply to the Waldringfield conifers described above.

These four records represent the first accounts of fossil coniferous woods from Suffolk, and there are, surprisingly, few other previous descriptions of such woods from the Cainozoic of England with which to make comparisons.

Carruthers (1878) identified and named Cedroxylon worthingense in a pebble found near Worthing, Sussex, presumably from the Upper Palaeocene (Thanetian) rocks which have yielded other Palaeogene plants in that vicinity (Chandler, 1964; Collinson, 1983). Unfortunately, the type and figured specimens of this species are apparently lost, and the published description and illustrations do not permit detailed comparisons. The Reading Beds of Aldworth, Berkshire, were the source of a piece of wood which the late Prof.

E. W. Jane identified as a Sequoia sp. (Chandler, 1964). Edwards (1930) gave a brief account of coniferous root wood, Glyptostroboxylon tenerum (Kraus) Conwentz, found in a concretionary block of Thanetian sandstone ('greywether' or 'Sarsen') from the Marlborough Downs near Swindon, Wiltshire. Other taxodiaceous woods, including tree stumps and in situ roots, have been reported from the Upper Eocene (Fowler et al., 1972) and Lower Oligocene (Brett & Edwards, 1970) sediments of the Hampshire Basin, the former being assigned to a Glyptostroboxylon sp. also. In terms of quantity, the London Clay is the most important source of Palaeogene coniferous woods in Britain. Approximately 24% of one sample of wood fragments collected from this horizon at the Isle of Sheppey, Kent, proved to be homoxylic, probably coniferous (Scott & deKlerk, 1974). In addition to this pyritic material, the London Clay at Faversham, Kent, has also yielded calcified coniferous wood showing much better preservation of anatomical details; Seward (1919) described the unique specimen of Cupressinoxylon holdeniae from that locality.

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It cannot be concluded that specimens of the form-genera Cedroxylon, Glyptostroboxylon or Cupressinoxylon necessarily represent the woods of Cedrus (cedar), Glyptostrobus (Chinese swamp cypress) or Cupressus (true cypresses) respectively. Seward (1919) considered that Cupressinoxylon had wood anatomy comparable to that of both the Cupressaceae (true cypress family) and Taxodiaceae (swamp cypress family), each with a fossil record extending back at least to the Jurassic Period. Similarly, he compared Cedroxylon to both the Pinaceae (pine family) and Cupressaceae, but was able to give a more certainly taxodiaceous affinity to Glyptostroboxylon.

English Cainozoic fossil conifers are further represented by remains of their leafy shoots, cones, cone-scales, seeds and pollen grains. Such material indicates the presence of the Araucariaceae (kauris and monkeypuzzles), Cephalotaxaceae (plum yews) and Podocarpaceae (yellow-wood or totara family) in addition to those families whose occurrence is indicated by the woods mentioned above (Chandler, 1964,1978; Andrew & West, 1977).

Although the existing, native coniferous flora of Britain includes species of the Cupressaceae, Pinaceae and Taxaceae (true yew family) only, Pennington (1974) commented upon the persistence of the Taxodiaceae in this country up to the end of Neogene times. It is noteworthy that today the Araucariaceae do not range further north of the Tropics, and that the Podocarpaceae are found mostly in the Southern hemisphere.

Appendix The fossil plants described above are part of the collection of the Plants Section of the Department of Palaeontology, British Museum (Natural History) in Cromwell Road, South Kensington, London SW7 5BD. As such, each has been registered with a 'V' number as follows:(i) W o o d from Botesdale Chalk; V.53717. (ii) Cedroxylon sp., V.7818-7820 and V.53513. (These four slides were all sectioned from one specimen.) (iii) Conifers from Waldringfield; Three microscope slides, V.8015, V.8051 and V.53512 only. (Apparently not from the same block. Although lacking in precise locality details, V.53512 is labelled 'Cupressinoxylon.

Derived from the London Clay. Cut from a specimen belonging to G.P. H o p e Esq.') (iv) Conifer from Ipswich. D. H . Scott Collection, nos. 365 and 366.

Acknowledgements Dr. P. J. Grubb of the Botany School, University of Cambridge, kindly assisted me with the loan on the holotype of Cupressinoxylon holdeniae. I thank the staff and trustees of the British Museum (Natural History) for permitting me to examine the specimens in their care.

References A n d r e w , R. & West, R. G. (1977). Pollen spectra from the Pliocene Crag at O r f o r d , Suffolk. N. Phytol., 78, 709.

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Brett, D. W. & Edwards, N. (1970). Pyrite crystals in the parenchyma cells in wood of fossil root. Nature, Lond., 27, 836.

Carruthers, W. (1878). Description of Tertiary plant-remains from Bracklesham and Worthing, Sussex, pp. 162-7, in Dixon, F. & Jones, T. R. The Geology of Sussex. W. J. Smith, Brighton.

Chandler, M. E . J. (1964). The Lower Tertiary floras of southern England.

IV. A summary and survey of findings in the light of recent botanical observations. British Museum (Natural History), London.

Chandler, M. E. J. (1978). Lower Tertiary floras of southern England. V. Tert. Res. Spec. Paper No. 4., London.

Chatwin, C. P. (1961). East Anglia and adjoining Areas. (4th Ed.) Br. Reg. Geol., H . M . S . O . , London.

Collinson, M. E. (1983). Fossil plants of the London Clay. Field Guide to fossils. No. 1. Palaeontological Association, London.

Edwards, W. N. (1930). Coniferous roots in Sarsen stones. Marlborough College Nat. Hist. Soc. Rep. 78, 41.

Fowler, K., Edwards, N. & Brett, D. W. (1972). In situ coniferous (taxodiaceous) tree remains in the Upper Eocene of southern England.

Palaeontology, 16, 205.

Pearson, H. L. (1987). Megafossil plants from Suffolk: a review of the pre-Pleistocene records. Trans. Suffolk Nat. Soc., 23, 56.

Pennington, W. (1974). The history of British vegetation. (2nd Ed.) Hodder & Stoughton Educational, London.

Scott, A. C. & deKlerk, R. (1974). A preliminary study of London Clay pyritised 'twigs' from the Isle of Sheppey. Tertiary Times, Bromley, 2, 73.

Seward, A . C. (1919). Fossil Plants. Vol. 4, Camb. Univ. Press, London.

West. R. G . (1977). Pleistocene Geology and Biology. (2nd Ed.) Longman, London.

H. L. Pearson Emmanuel College, Cambridge, CB2 3AP.

Current address: Claydon High School, Church Lane, Claydon, Ipswich IP6 OEG

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