In April 2018 we had the pleasure of being invited on a tour of the herbarium at Hunter Region Botanic Gardens by two of the volunteers there - Andrew Pengelly and Kathleen (Kat) Bennett. We are also very lucky to have Andrew and Kat as members of HOGS. For many who attended, the purpose of a Herbarium was mysteriously unknown to us prior to the visit so it was a wonderful learning experience.
A herbarium is a repository for plant specimens. The specimens are samples of plants collected in the field that have been pressed, dried out and mounted in a particular way before being cataloged in a database and stored away. The collection can then be used for scientific research and/or as a general reference for plant lovers to help with plant identification. Every state of Australia has its own herbarium, but there are many regional ones in botanic gardens and universities too. They tend to focus mostly on the plants which grow in their surrounding area. Prior to the establishment of these Australian herbariums, collectors would need to send their specimens overseas (to Kew, Paris, etc) to be identified.
When a collector is out in the field, they bring with them a handmade portable press. The press is made up of pieces of cardboard (with corrugation to help with air flow) and newspaper that is sandwiched together by pieces of ply wood. All of these pieces are fastened together with adjustable straps. Andrew demonstrated two pressings, a camellia and a eucalypt. When pressing the plant, it is important to preserve the most identifiable features, such as the flower, fruit and bud. This is important for identification purposes, but it is not always possible since not all features may be available depending on season. He lays the plant in between a fold of newspaper, the most critical part in the whole procedure. It is important to keep it as natural as possible, turning a 3d object into a 2d one without allowing it to crease or break. Due to their size, some specimens need to be trimmed down or bent to fit to the page. Kat explained that for large specimens a Z bend is commonly used. The plant is bent in a zig zag fashion so that the bottom and top of the plant still remain erect. If seeds of the plant are available, they are kept separately in a small envelope.
Once the specimen is laid down as best as it can be, it is placed between two pieces of cardboard and weight is applied to it immediately. Jewellery tags are used to record the collectors code number which corresponds to a log of collected specimens they keep in their own personal field book/journal. The collector also notes down the GPS location (latitude, longitude and altitude) of where the specimens was collected as this data can be used later to create distribution maps using information herbariums all over Australia & the world.
The collected specimens are then taken back to the herbarium for identification. For some specimens, such as grasses, Kat showed examples of how they are required to work through a big clump of grass which could include 50 or more specimens. She is required to sort through and find one or two that best demonstrate all the features of the grass for identification and then mounting.
Kat is an expert at mounting specimens. She has a real skill at restoring them to their natural appearance, especially when the specimen arrives at the herbarium all bunched up and distorted. She explained her mounting method is to start at the bottom and take the two outer most stems/flowers which she mounts first to fit the page. She then slowly teases out the other stems/flowers so that the plant opens up and you are able to better see its true growth habit as well as other important features, e.g. whether the leaves are opposite or paired. Kat uses a needle and dental floss to carefully tie the specimen to the paper using a square knot at the top. Other collectors use tape instead, and some older collectors would use glue but the glues can be corrosive to the plant material.
Each mounted specimen is then labelled with their family name, botanical (binomial) name, the name of the collector, the collectors number, an accession number given by the botanic gardens, the location where it was collected from (including the GPS details), and a bit of information on the characteristics of the area it was found in. The specimens are then kept in a freezer for around a week to kill off any “nasties” that may be a threat towards their preservation. Afterwards they are taken into the cool room where they are stored in boxes that line the walls on shelves. The room is temperature controlled with an air conditioner. The boxes are divided into two groups – monocots and dicots. Each group is ordered alphabetically by their family name. Ferns and fungi are kept separately.
The herbarium has many major collections that have been donated including those from Terry Tame, William Bill Dowling, Anne Heinrich and Marie Elliot – all of whom are very highly respected plant/fungi collectors from the hunter, past and present. The herbarium will actually be renamed on 30 April to the ‘Terry Tame Herbarium’ in honor of his contributions.
We all had a chance to look at the specimens under the microscope, gaining a true appreciation of the external features used to identify a plant which are not easily picked up with the natural eye e.g. whether the hairs on the leaf are flattened, rigid, glandular, if they swell at the bottom, etc.
Once identified the specimens are entered into an electronic database that was developed by IT volunteers at the gardens. Many of the specimens are also then listed on the Bionet Atlas so that their information is available for the whole world to see. Online herbariums are becoming very popular these days with photographs and scanned images of pressed specimens used.
The herbarium also has an extensive library of books about plants, gardening, agricultural techniques, pests and diseases, propagation, etc which is available as a resource to the public to access on site. And the volunteers are also happy to help identify plants for you if you bring in a specimen on a Monday or Tuesday when the herbarium is open.
The field day was a real eye opener to us all and we were all very grateful for the experience of seeing this completely different aspect of plant appreciation and research. I think many of us will be looking at plants differently from now on, and even having a go at pressing them ourselves! The mounted specimens were truly beautiful and could easily be treated as artworks and framed and displayed at home for their viewing pleasure.
Thanks very much to Andrew and Kat!