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Herbarium collections

 Dried plant specimens are stored as a reference for plant identification in collections known as herbaria. Well-labelled and kept under controlled conditions of low humidity, they can be kept for reference indefinitely, while living plants are much more susceptible and their survival as a point of reference cannot be guaranteed. When a new species is named it is linked to a stored herbarium specimen, the ‘type’ for that name. Databases of collections are currently being developed, and images of many collections, especially the types, are becoming available online in ‘Virtual Herbaria’.    More...

 

Herbaria
Virtual Herbaria (Online plant specimen images) 
  • Europeana - Specimens in collaborating European institutions - search by botanical name
  • JSTOR Plant Science - search herbarium collections (all institutions - go to institution for image)
  • Encyclopedia of Life (1.7m images - low resolution herbarium specimens)

Individual Institutions’ Virtual Herbaria:   Growing list kept by Kew

Bamboo specimen images

 

 

 

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Herbaria are found in botanical institutions throughout the world. A network of cooperating herbaria permits the exchange of collections on loan for direct comparison. Herbarium collections are most useful as a specialist resource for those who revise and describe plants and their names. They are very important, not least because this is where the ultimate reference material for bamboo names is located. Good comprehensive collections are critical for good nomenclature in other ways as well. Accumulating a large number of specimens from throughout the range of a species allows botanists to understand the variation to be found within that species, and helps to refine the boundaries between similar species.

 

Some of the difficulties associated with the identification of living plants by direct comparison with herbarium specimens:

Herbarium sheet
  • Herbarium material is pressed flat and completely desiccated, which makes it rather different in appearance from fresh material
  • Unless a specimen is the actual type specimen for that species, there may be several different names attached to it
  • Different herbaria arrange their plants following different classification systems, often out of date for bamboos, making species hard to find
  • Knowledge of which parts of bamboos are important for identification used to be poor, and older herbarium collections often lack more important parts, such as culm sheaths, or even leaves
  • Different herbaria specialise in different plant groups and plants from different areas, and those that have comprehensive bamboo collections are few and far between
  • As long-term preservation of the specimens is of paramount importance, fresh material is not allowed in the herbarium for direct comparison, because it could harbour pests
  • Herbarium material is fragile, and staff are cautious about allowing too much handling, as it has to be stored indefinitely

 

 

Increasingly, herbarium specimens are being digitized, catalogued, and made available on-line, especially the type collections, but this is a colossal and expensive task. This will help to protect
Dutch herbaria databaseDutch herbaria database
collections as they do not need to be physically handled or shipped so often. They also become much more widely available, but unfortunately that does not always mean that they help in quick plant identification. Recognizing bamboos from good images of excellent specimens may be possible, but quality of either pictures or specimens, or both, can make identification much more problematic.

The finer details of bamboo plants often require a very close inspection, usually using a microscope. Higher resolution images are becoming available, their use being somewhat restricted by the large file sizes involved, but they still do not have the resolution of a good microscope, or macro camera lens. Herbarium specimens have not always been collected, mounted, or scanned in the best possible way for presentation of the parts that are critical for identification. Images of old herbarium specimens could be seen primarily as a screening tool to determine which ones should be requested on loan for closer inspection. Physical herbarium specimens should always be examined directly before any taxonomic changes are made. It is still wonderful to be able to see good quality images of important specimens, especially the type collections, and as standards of both herbarium specimens and their imaging improve with time, their wider availability will become a great help.

Some images of bamboo herbarium specimens can be found by searching the free on-line virtual herbarium collection databases of large institutions, see the links above, but not all herbaria have yet started to scan their collections, or even to database them, or to include bamboos. Some images of types are now available, and links to them have been included on the cultivated species pages here, e.g. for H. hookerianus.

There is still a problem with access to some data, which is often restricted. There are several initiatives to make such data freely available tThe Problem of the Yellow Milkmaid - Europeana White Papero all, e.g. the Open Archives Initiative, the Global Biodiversity Information Facility, Encyclopedia of Life, iPlants, Europeana Natural Europe Project, Herbaria United, and note that the institutions listed above provide free access. The benefits of opening up institutional data are eloquently presented in a Europeana White Paper related to the Rijksmuseum’s experience with its Vermeer - The Milkmaid.

However JSTOR Plant Science, the main organisation providing access to more than 1.4m images of collections from 260 participating institutions of the Global Plants Initiative, currently seems to only provides access to staff at the participating herbaria. The intention of the Global Plants Initiative, funded by the Mellon Foundation, under which the scanning of these collections has been arranged, seems to have been to allow much wider, free access, but that is yet to materialise through JSTOR. Meanwhile the JSTOR and Encyclopedia of Life search facilities are very useful for locating specimens, many of which can then be examined in more depth on individual herbarium websites. For specimens in certain European institutions, the Europeana site provides search and direct free access.

Older herbarium specimens are often very problematic, even for specialists, and they can be very hard to identify. Many might be discarded if sent in to a
Herbarium bamboo specimens are often difficult to identify
herbarium today. However, they are often of historic importance, especially when they provide the definitive reference ‘type’ for a botanical name. In older bamboo collections, because of a misconception that only flowers would provide a sound indication of a plant’s affinities, there are frequently no culm sheaths, and often no leaves either. This makes it very difficult to relate the older collections to living bamboos, or to more recent collections. This is especially problematic when competing names are tied to older, flowering material, and also to newer, solely vegetative collections. Poor labelling is another problem, along with inclusion of parts from more than one plant or species in the same collection.

A particular problem with bamboo herbarium material is that hairs and appendages such as auricles and oral setae may have fallen off, but these are often critical for species identification in the bamboos. Only by inspecting closely with a microscope is it possible to see remnants indicating where they were once attached. Colours also fade with time, especially if the collections have been exposed to strong light.

Newer herbarium collections are usually more comprehensive and in better condition. Botanists today often photograph plants in the field as they make collections in order to get the best possible images of fresh material. Linking of such new images to the images of collections should now be possible. When digitizing herbarium collections it is to be hoped that close up photos of the more critical parts of collections will also be undertaken. Currently huge amounts of memory may be used up recording the blank mounting sheets, while important parts of the plant are not recorded in sufficient detail.

Thus we need better specimens (including new epitypes to support poor quality types), improved imaging of the critical diagnostic parts, and wider online availability, as well as better linkage between the different sources of data and information available.

 

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