DISCONNECTION and RECONNECTION: MISCONCEPTIONS and RECOMMENDATIONS PERTAINING to VOUCHERS in WOOD SCIENCE Jennifer Barker This P

IAWA Journal, Vol. 29 (4), 2008: 425– 437

DISCONNECTION AND RECONNECTION: MISCONCEPTIONS AND RECOMMENDATIONS PERTAINING TO VOUCHERS IN WOOD SCIENCE

Jennifer Barker CRC for Australian Weed Management, PMB 1, Waite Campus, University of Adelaide, Glen Osmond SA 5064 [E-mail: [email protected]]

SUMMARY This paper aims to raise awareness of the importance of plant specimen vouchers in wood anatomy and wood identification in keeping abreast of plant name changes. It reveals the strong possibility that many wood specimens in xylaria are currently misidentified because corresponding plant specimen vouchers have been lost or separated from collections and not revisited. It appeals to the systematic wood anatomy commu- nity to reconnect wood specimens in xylaria with their corresponding plant specimen vouchers in order to update nomenclature. More specific recommendations are aimed at the International Association of Wood Anatomists (IAWA) to promote and educate those in the wood commu- nity on the importance and value of plant specimen vouchers in wood identification and systematic wood anatomy. Of equal importance is the adoption and promotion of a wood specimen citation system that unam- biguously indicates whether research is based upon wood specimens with corresponding plant specimen vouchers and whether these vouchers have been consulted so that the research reflects current nomenclature. Key words: Wood identification, systematic wood anatomy, taxonomy, plant specimen voucher, herbaria, xylaria.

INTRODUCTION

… reference collections of wood backed by herbarium vouchers serve as a tool which is essential to the wood anatomist and herbarium taxonomist alike. The two classes of material must be kept together. (Metcalfe & Chalk 1988: 5)

Index Xylariorum (Stern 1988) indicates that many xylaria with vouchered wood specimens do not retain the associated plant specimen vouchers.1 The online US National Herbarium (USw) database (2005) states that 60% of their wood collection is vouchered but that, while most plant specimen vouchers are in the US National Herbarium (US), a significant number are in other herbaria. Similarly, while 85% of theAustralian Wood

1) The links to be maintained between wood specimens and plant specimen vouchers recom- mended throughout this paper are shown in Figure 1.

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Collection (FPAw) is said to be authenticated with plant specimen vouchers (Stern 1988), the vouchers are deposited in various Australian and overseas herbaria ( Stern 1967: 27; Ilic 2002: pers. comm.). The disconnectedness of many wood specimens within international xylaria with their associated plant specimen vouchers can be explained by a combination of historical and modern-day factors. These include the separation of plant taxonomy and comparative wood anatomy into specialist disciplines; the exchange and duplication of plant specimen vouchers and wood specimens between xylaria and herbaria; storage issues; competing interests in plant specimen vouchers; and a shortage of funding and staff that has meant many xylaria are no longer curated. Unfortunately, this has meant that wood specimens are infrequently or never reconnected with their corresponding plant specimen vouchers in order to reflect any changes in plant names, or to correct misidentifications of the original material. For xylaria like the Australian Wood Collection (FPAw) it may have been at least 50 years since many of the vouchered wood specimens were originally collected. With plant names changing considerably in this time – as knowledge of the worldʼs flora increases and is revised – one cannot have full confidence in the original identifications of these wood specimens without revisiting the corresponding plant specimen vouchers. Indeed, this research reveals that approximately 50% of the identifications given for a surveyed collection by R. Schodde and L.A. Craven of 285 vouchered wood specimens belonging to the US National Herbarium no longer match the identification of their corresponding plant specimen vouchers (for the full survey see http: //home.iprimus.com.au/jabarker/Appendix1.doc). In many cases, the level of identification had improved, demonstrating that reconnecting with voucher specimens can reinvigorate collections and increase their scientific potential. This paper also reveals that the value and function of plant specimen vouchers is often misunderstood. For example, in an informal survey conducted of existing Australian wood identification resources (Barker 2005), one correspondent2 replied:

Probably 95% of the collection has been botanically authenticated, however we have not kept the botanical specimens as well. Specimens supplied by other institutions generally only have botanical name[s] and are assumed to be authenticated by the collector.

It was found that routine identifications of unknown wood specimens for the public are being conducted by comparison with wood specimens that were not collected with a corresponding plant specimen voucher (unvouchered), or with reference wood specimens where the connection with the corresponding plant specimen vouchers has not been maintained. Moreover, many publications and keys are founded on reference wood specimens like these, which perpetuates the risk of misidentification by people who use the resources to assist with their identification work. Wood specimen numbers and plant specimen voucher numbers are not always both cited in publications making

2) This quote from the survey has been kept anonymous as it is not seen as necessary to expose individual practices.

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it impossible to revisit plant specimen vouchers to update names, and to revisit wood specimens to check wood descriptions. This paper aims to explain why plant specimen vouchers need to be at the foundation of all wood anatomical research, wood identification publications and keys, and routine wood identifications conducted for scholarly and scientific purposes. Further, all publications emanating from this research should cite both the wood specimen number and location and plant specimen voucher number and location (if different). In an often overlooked short communication, Baas (1980) has argued the importance of citing plant specimen vouchers of studied wood specimens, rather than xylarium accession numbers. This paper gives an additional background and more specific recommendations.

What is meant by a voucher? When discussing new publications or research, most taxonomists will ask: “Is it vouchered?” Vouchers are representative specimens of plants or animals. They are the foundation of and fundamental to any science that relies on the names of organisms to communicate information about that organism, e.g. zoology, botany, ecology, entomology, ornithology, archaeology, molecular studies and wood anatomy – acting as a ʻreceiptʼ for the research that is revisitable in the event of name changes. Vouch- ers are deposited in appropriate repositories (such as herbaria or museums) where they are properly curated so that they may be revisited to repeat experiments or check identifications. Any description or identification that is based on a biological specimen that has been separated from its associated voucher is subject to error. Furthermore, anyone who applies descriptions or uses an identification key based upon unvouchered biological specimens, or specimens that have lost their connection with associated voucher material, seriously jeopardises their own research. This is so even if the identifications are correct at the time for it does not protect a species against future name changes. Many scientific journals require research papers to be based on vouchered specimens. In other scientific journals, the use of vouchers in research is not a condition of publication but the practice is encouraged (see, for example, instructions to authors for Annals of the Entomological Society of America, Canadian Journal of Zoology and Subterranean Biology). In Subterranean Biology a waiver may only be issued by the editor of the journal and the lack of voucher specimens must be acknowledged in the paper (Cobolli 2006). In most sciences underpinned by named organisms, the importance of vouchers is addressed in papers (e.g. Stern & Chambers 1960; Martin 1990; Huber 1998; Agerer et al. 2000; Bates et al. 2004; Funk et al. 2005) and book sections ( Metcalfe & Chalk 1988: 5; Forman & Bridson 1989: 147) dedicated to the subject. Yet there are still many examples in technical and popular scientific literature where vouchers are discarded upon identification (e.g. Moore 2005), if they are collected at all (e.g. see examples in Meerman & Boomsma 1993; Hosking et al. 1996; Smith et al. 1998). Many wood specimens within international xylaria are ʻauthenticatedʼ by plant specimen vouchers – a branch with leaves, fruits and/or flowers collected from the

Downloaded from Brill.com10/03/2021 07:21:14PM via free access 428 IAWA Journal, Vol. 29 (4), 2008 Barker — Vouchers in Wood Science 429 same tree from which the wood specimen was removed. This plant specimen voucher is reserved for professional identification by botanists or plant taxonomists and is usu- ally deposited in an institutional herbarium.

Why are plant specimen vouchers necessary in wood anatomical research? There are good reasons for plant specimen vouchers and their absence can seriously damage the scientific integrity and value of wood specimens. 1) To confirm identifications which cannot be based on wood alone – Most wood scientists will understand the importance of underpinning wood specimens with plant specimen vouchers since wood alone often does not possess sufficient diagnostic features to obtain a reliable identification at species level. A wood collection can rarely be confirmed below genus level based on wood characters alone. 2) To protect against erroneous identifications – Botanists do make mistakes both in the field and in the herbarium and their identifications should always be viewed with caution. Misidentifications may occur because botanists are required to deal with taxa outside of their area of expertise and they may apply an out-of-date concept in identifying a plant specimen voucher. Additionally, the flora of the region in which the wood was collected may be poorly known or the plant specimen voucher may be inadequate for definitive identification. 3) To ensure the science is revisitable and repeatable – One of the basic tenets of science is that research must be revisitable and experiments repeatable. In wood anatomy, the wood specimen must be revisitable to test, repeat or expand upon experiments or to query descriptions, while the plant specimen voucher must be permanently stored to allow its revisitation to confirm its identification. In wood anatomy, this is only pos- sible if the connection between the plant specimen voucher, the wood specimens and any resulting research data and publications is maintained (see Fig. 1). 4) To protect against changes to plant names – It is by examination of the variation in botanical specimens that identifications (and revisions) of species are made. Link- ing wood specimens to plant specimen vouchers means that the wood can be updated to reflect any name changes. However, many non-systematists do not realise just how frequently plant name changes occur. In Australia, in the twelve years from 1988 to 2000, a further 300 Eucalyptus species were recognised (Chippendale 1988; Brooker 2000), while in an eighteen year period between 1982 and 2001, the number of Acacia species recognised by systematists increased by 250 to 955 species (Elliot & Jones 1981; Orchard & Wilson 2001). My case study reconnecting Papua New Guinean wood specimens and their associated plant specimen vouchers revealed that 50% of vouchers had changed their name since they were collected in the 1960s (see http://home.iprimus.com.au/jabarker/ Appendix1.doc).

There are several kinds of name changes: a) Straightforward replacement of name – Sometimes name changes are straightforward. For example, a group of Australian Eucalyptus species known as the Bloodwoods

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Field Collection •Duplicate collections are made of both the wood specimen and the plant specimen voucher •Wood and plant specimen voucher are given the same unique collection number

The connection between wood specimen and plant specimen voucher Wood specimen must always be retained and the plant Plant specimen voucher specimen vouchers revisited periodi- •Duplicates deposited in cally to check names •Duplicates deposited in xylaria/herbaria herbaria •Underpins activities based •Formerly identified by plant on systematic wood taxonomists anatomy: •Contribute to taxonomic revisions: name may change

Research / Published Identification Reference publications descriptions keys / atlases specimens of wood in routine wood All publications / reports/ research must identifications cite plant specimen voucher numbers as well as wood specimen numbers and plant specimen vouchers must be revisited to check names

Multi-disciplinary publications & identifications e.g. in archaeology, palaeobotany, forensics, and civil/criminal law where wood research and routine identifications are cited and keys and atlases are applied to identify unknown wood specimens } Figure 1

are now commonly referred to as Corymbia (Hill & Johnson 1995; Nicolle 1997) even though some taxonomists persist with Eucalyptus (see Brooker 2000; Brooker et al. 2002). In most cases, the same epithet applies, e.g. Corymbia terminalis (F.Muell.) K.D. Hill & L.A.S. Johnson is synonymous with Eucalyptus terminalis F.Muell. Simi- larly, in a revision of the Sapindaceae family (Reynolds 1987), Heterodendrum was reclassified as Alectryon, e.g. Heterodendrum oleifolium Desf. is now referred to as Alectryon oleifolius (Desf.) S.T. Reynolds. b) Combining two or more existing species – For example, the widespread and variable Pandorea pandorana (Andrews) Steenis occurs in Indonesia, New Guinea and Australia. In the past the eastern states of Australia used this name but the central Australian species was considered different and referred to as Pandorea doratoxylon (J.M. Black) J.M. Black. These are now considered to be the one species, Pandorea pandorana. c) Splitting an existing species into two or more species – When a single species is split into two or more species on morphological grounds, sometimes the resultant species are separable by geography. For example, in 1994, Eucalyptus microtheca F.Muell. was separated into two species so that central Australian populations are now known as E. coolabah Blakely & Jacobs with E. microtheca now restricted to northern Australia (Hill & Johnson 1994). Wood specimens from the area in which the two species overlap – or wood specimens where geographic location details are not retained – would be virtually impossible to identify without returning to a plant specimen voucher.

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Other species that are split on a morphological basis are virtually impossible to tell apart without recourse to a plant specimen voucher. For example, the northern and north- eastern Australian species Acacia aulacocarpa A.Cunn. ex Benth. is now divided into eight species (Maslin 2001) while the central Australian species complex Acacia aneura F.Muell. ex Benth. is now split into five species and ten varieties. Without revisiting any associated plant specimen voucher, updating the name of a wood specimen of A. aneura or A. aulocacarpa to reflect these name changes is impossible.

Misconceptions about plant specimen vouchers in wood identification resources and practices In a survey of wood identification resources (Barker 2005), several recurring observa- tions were made that relate to misconceptions as to the importance of plant specimen vouchers.

Insufficient information within the current wood citation system In many wood anatomy publications, it can be impossible to tell whether a cited specimen number refers to: 1) a wood specimen without a plant specimen voucher; 2) a wood specimen connected to a plant specimen voucher that has not been cited; 3) a wood specimen and a plant specimen voucher that share the same specimen- number. For example, in the American Journal of Botany – a journal that requires and publishes lists of plant specimen vouchers – a paper examining the wood anatomy of Dodonaea viscosa cited 102 specimens (Liu & Noshiro 2003: in supplementary data p. 1). Typical citations were MADw 3331, SJRw 24153, FPAw 7834 etc. which refer to the wood specimen locations – as per Index Xylariorum (Stern 1988) – and accession numbers. These citations provide no insight into the existence or location of an associated plant specimen voucher. One would need to make enquiries of oneʼs own in order to establish whether the cited specimens were tied to vouchered material.

Failure to periodically revisit plant specimen vouchers It is not just the citation system that is confusing. Even assuming these 102 wood specimens are tied to plant specimen vouchers, how can we be sure that the plant specimen vouchers have been revisited to update their names or correct their identifications? It is difficult to know what percentage of wood specimens within international xylaria can be reconnected with their corresponding plant specimen vouchers. However, without revisiting these vouchers, a percentage of all wood collections will be misidentified.

Claiming research/publications are based on authenticated material when plant specimen vouchers have not been revisited Some publications claim to be based on an “authenticated wood collection” or a “wood collection supported by vouchers”. Use of these phrases suggests an exactitude

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that may be misleading if the vouchers have not been revisited to update names or correct misidentifications. While such a statement may be technically correct, much confusion – not to mention misidentifications – can be perpetuated. Such a claim was made in the otherwise excellent CSIRO Atlas of Hardwoods (Ilic 1991: 1) which is based on specimens from the Australian Wood Collection (FPAw) in Victoria, Australia. Until the connection is made between the wood specimens and their plant specimen vouchers in various herbaria, it is impossible for any subsequent editions of the CSIRO Atlas of Hardwoods to be properly and accurately updated. In the meantime, many identifications have to be regarded with suspicion – including those of Eucalyptus microtheca, Acacia aneura and A. aulacocarpa (see earlier this paper) which are all present in this atlas. An added frustration is that all research that claims to be based on “authenticated” or “vouchered” specimens is thrown into question. It needs to be clearly stated in papers, reports and keys that plant specimen vouchers have been revisited to re-examine the original identifications and update names in the course of the research.

Failing to record specimen numbers in publications Another common oversight is the failure to retain both the wood specimen numbers and locations, and the plant specimen voucher numbers and locations (if different), in publications. This information is lacking in many of the consulted identification keys and atlases (e.g. Ilic 1991; Heiss 2005; Richter & Dallwitz 2005). Absence of such numbers in many wood identification resources is concerning since users expect the information presented to be reliable and revisitable, particularly if they are to pin their own research on identifications gleaned from these resources.

Basing contemporary descriptions on earlier literature Some publications and keys on wood anatomy utilise previous research to provide, or augment, wood descriptions. This is acceptable if the wood specimens used to con- duct the original research have been retained to allow their revisitation. In addition, the wood specimens must have corresponding plant specimen vouchers, and both the wood specimen numbers and plant specimen voucher numbers must be recorded in both the original research, and any publications that utilise this research, so that nomenclature can be updated as necessary. The InsideWood (2004) website integrates information from various sources for a single species. For example, at the time of review, the description of the wood of Eucalyptus microtheca was taken from a paper by Dadswell (1972). Wood specimen numbers are not provided with the InsideWood description. This is not surprising since Dadswell did not cite in his paper the specimens that contributed to his treatment of Eucalyptus. As we have seen, for much of its previous distribution Eucalyptus microtheca is now Eucalyptus coolabah (see earlier this paper). How can we trust that the description in Dadswellʼs paper – and now reproduced on the InsideWood website – is of E. microtheca and not E. coolabah? Images of E. microtheca on the InsideWood website are attributed to wood specimen FPAw 1736 but a plant specimen voucher number and location is not provided. How do we know if a plant specimen voucher exists and whether it has been revisited to check that this identification is still correct?

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Relying only on botanistsʼ identification skills An argument occasionally put forth in scientific publications (e.g. Metcalfe & Chalk 1988: 5; Smith et al. 1998: 5) is that where specimens have been identified by botanists, it is not necessary to keep plant specimen vouchers. Metcalfe and Chalk (1988) claim that where scientific names have remained stable since collection of the wood – particularly at the genus level and sometimes even at the species level – the identifications of the unvouchered wood specimens are probably still correct. This may possibly be true for common European tree species but we have already seen that it is not the case in countries where the flora is still being documented. Even if they did not make mistakes no botanistʼs expertise in identification can account for name changes that occur with advances in knowledge.

DISCUSSION This paper makes several suggestions for improving wood anatomical and wood identification methods to ensure that research is based upon solid taxonomic principles. The International Association of Wood Anatomists is the logical body to spearhead these proposals. Current systems will only be changed and improved if the IAWA makes adherence to these systems a prerequisite for publication or, at the very least, “best practice”.

Base IAWA Journal on research supported by plant specimen vouchers The journal Mycological Research recently made the deposition of fungal specimen vouchers that supports research a prerequisite of publication (Agerer et al. 2000: 644). Examples of the many scientific journals with similar requirements were given earlier in the paper. Although the editors of the IAWA Journal insist on optimal specimen citation in papers on systematic wood anatomy (Baas 2008: pers. comm.), the importance of plant specimen vouchers is not acknowledged in the “Instructions to Authors”. I recommend that this be included and also that future editions of the lists of characters for hardwood (Wheeler et al. 1989) and softwood (Richter et al. 2004) identification should stipulate these “best practice” methods for documentation. The inclusion of specimen numbers in scientific journals additionally illustrates the important role that biological specimens play in research; this provides important justification for the preservation and maintenance of natural history collections (Funk et al. 2005: 127).

Encourage the reconnection of wood specimens with plant specimen vouchers Index Xylariorum (Stern 1988) records that many xylaria maintain a record of where plant specimen vouchers have been deposited. To reconnect xylaria with their plant specimen vouchers and update the names on wood specimens would be a very useful undertaking. As my case study demonstrated (see http://home.iprimus.com.au/jabarker/ Appendix1.doc), apart from increasing the scientific legitimacy of wood collections, their scientific value may be increased if wood specimens that were previously only known to genus are now identifiable to species. The increasing accessibility of electronic

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databases maintained by herbaria may mean that cross-checking wood specimens against plant specimen vouchers may not require the physical visitation of the specimens, although mistakes and outdated identifications will also occur in databases.

Comprehensively address plant specimen vouchers in future editions of Index Xylar- iorum The consulted editions of Index Xylariorum (Stern 1967, 1988) have addressed plant specimen vouchers but only to the extent that they cite the percentage of the wood collections that are vouchered. This is not enough. In the next Index Xylariorum it should be attempted to indicate for each xylarium record whether plant specimen vouchers exist and where they are located.

Encourage the collection of plant specimen vouchers in the field A paper in the journal of the International Wood Collectors Society (IWCS) explains the importance of plant specimen vouchers in wood identification (Barker 2003). The article promotes greater links between IWCS branches and local herbaria and encour- ages those members who collect in the field to collect a plant specimen voucher and to reserve a specimen of wood – both for lodgement in herbaria (or xylaria). In return, IWCS members will receive professional taxonomic identifications of their wood and they may choose to retain the specimen number with any wood they trade or any items that they produce from the wood. This will mean that the correct identity of the wood (or objects made from it) can always be maintained by contacting the herbarium in which the plant specimen voucher was lodged. Forman and Bridson (1989) provide useful guidelines on plant collecting.

Ensure wood specimen and plant specimen voucher number(s) and location(s) are appropriately cited in all publications Apart from Sternʼs (1988) xylarium abbreviations, and despite an attempt to introduce a system in 1960 (Stern & Chambers 1960), a standard system for citing wood has not been achieved. Baas (1980) convincingly argued that only the plant specimen vouchers need to be cited but unfortunately this simple solution is not always adopted. A new and standardised system is desirable that efficiently communicates the following information: – The wood specimen number; – The location of the wood specimen; – The plant specimen voucher number; – The location of the plant specimen voucher; – Whether the plant specimen voucher has been revisited to update any changes to names; – Whether the plant specimen voucher has not been revisited to update any changes to names; – If a plant specimen voucher does not exist; – If a plant specimen voucher is thought to exist but can not be located.

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However, it is difficult to efficiently account for so many variables in a citation system. Therefore, until a practical and standardised system can be developed, it is still necessary to clearly state this information for each wood specimen in each research paper, publication and key and within any wood identification report. Where research is based on large numbers of specimens, the data may be most effectively presented in tabulated form. If specimens come from the same sources, all that may be required is a clear blanket statement that addresses all the information. All available specimen numbers – for both the plant specimen voucher and wood specimen – should be listed along with their locations. It is proposed that this system or a similar standard for citations is presented in the “Instructions to Authors” for the IAWA Journal. It is only by making this information a prerequisite of publication that we can standardise our methods and improve on current practices. This paper also suggests that IAWA members discuss the adoption of a standard system for new accessions acquired through field collection where the plant specimen voucher and wood specimen maintain the same number. The collector and collectorʼs number will probably be appropriate in most cases. This will make citations simpler and – as long as the location of the specimens (as per Index Xylariorum and Index Herbariorum) continue to be cited along with the collectorʼs number – it will simplify searches if plant specimen vouchers and wood specimens become separated. The col- lectorʼs number might also link to a paper-based or electronic collectorʼs ʻbookʼ which will provide another source (apart from electronic herbarium and xylarium databases) for searches.

Teach the importance of taxonomic principles in wood anatomy and wood identification subjects With wood anatomy and wood identification largely being taught within Forestry departments, it is important to cultivate students so that they are properly educated in the basic principles of taxonomy. Wood anatomy students need to be taught about “best practice” methods of research; the limitations and confusion surrounding common names; the circumstances in which scientific names are changed and revised and how often these changes take place; the importance of maintaining the connection between plant specimen vouchers, wood specimens and any publications emanating from their study; the diminished value of wood collections and publications where plant specimen voucher and wood specimen have not been reconnected; the limitations of unvouchered wood; and how to collect a suitable plant specimen voucher.

Recommendations IAWA members might consider the following proposals: – Promote plant specimen vouchers as “best practice” – Add a requirement to the IAWA Journalʼs “Instructions to Authors” that submitted papers on systematic wood anatomy be supported by plant specimen vouchers and

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publish lists of plant specimen vouchers and wood specimens that contribute to the research. This requirement could be waived by the Chief Editors of the IAWA Journal in exceptional circumstances; – Adopt an unambiguous wood citation system and promote it in the IAWA Journal, on the IAWA website and in future editions of the standard lists of characters for hardwood (Wheeler et al. 1989) and softwood (Richter et al. 2004) identification; – Promote and encourage electronic databasing of major xylaria collections which include the plant specimen voucher number and location as well as the wood specimen number and location (if different); – For future field collections, promote the use of a single, unique collectorʼs number (typically collector initials and surname followed by a unique collection number) for wood specimens and associated plant specimen vouchers and stress the importance of retaining this number; – Encourage institutions where wood anatomy and wood identification are taught to educate students on fundamental taxonomic principles (including the importance of plant specimen vouchers) and introduce them to a standardised system of wood and plant specimen voucher citation.

ACKNOWLEDGEMENTS

This paper extends PhD research conducted in the School of Earth & Environmental Sciences at the University of Adelaide in South Australia. I acknowledge the support and advice of my supervisors Professor Robert Hill (Head of School of Earth & Environmental Sciences, University of Adelaide) and Dr Philip Clarke (Head of Anthropology/Manager of Science at the South Australian Museum.) For this particular paper, I thank two anonymous referees for their comments and Professor Pieter Baas (Leiden) and Robyn Barker (Honorary Research Associate, State Herbarium of South Australia) for helpful discussion and guidance.

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