EQUILIBRIO VEGETATIVO-PRODUCTIVO

Garden:

Botanical Garden was founded in 1762 as a small garden on 5 acres of land in the Figure 5.8 Japanese Garden at the Missouri

Botanical Garden. (Photograph by Jack Jennings/Courtesy the Missouri Botanical Garden).

Figure 5.9 Tropical greenhouse of the Berlin Botanic Garden at Dahlem.

centre of Cambridge. It was moved to the present location in 1831 when Prof. J.S. Henslow established it on newly-acquired land of the University covering 40 acres. The garden is artistically landscaped with sys- tematic plantings, winter-hardy trails, an al- pine garden and a chronological bed. The latter is in the form of a narrow bed (300 x 7 feet) divided into 24 sections, each contain- ing plants introduced during a 20-year pe- riod. Tropical houses are one of the major attractions of the garden and contain palms and other tropical plants.

Herbaria

It was again Luca Ghini who initiated the art of herbarium making by pressing and sewing specimens on sheets of paper. This art was disseminated throughout Europe by his students who mounted sheets and bound them into book volumes.

Although the herbarium technique was a well-known botanical practice at the time of Linnaeus, he departed from the convention of mounting and binding the specimens into volumes. He mounted specimens on single sheets, storing them horizontally, a practice followed even today.

From isolated personal collections, her- baria have grown into large institutions of national and international stature with mil- lions of specimens from different parts of the world. Index Herbariorum, edited by Patricia Holmgren (Figure 5.10) (Holmgren, Holmgren, & Barnett, 1990) lists the world’s important herbaria. Each herbarium is iden- tified by an abbreviation that is valuable in locating the type specimens of various spe- cies. The major herbaria of the world with approximate number of specimens in the or- der of importance are listed in the table 5.1. In India Central National Herbarium (CAL) of the Indian Botanic Garden, Botanical Sur- vey of India, Kolkotta has over 1.3 million specimens. The herbarium of Forest Re- search Institute, Dehradun (DD) and National Botanical Research Institute, Lucknow (LUCK) are other major herbaria in India, with collections from all over the world.

Roles of a Herbarium

From a safe place for storing pressed speci- mens, especially type material, herbaria have gone a long way in becoming major cen- tres of taxonomic research. Additionally, herbaria also form an important link for re- search in other fields of study. The classifi- cation of the world flora is primarily based on herbarium material and associated lit- erature. More recently, the herbaria have gained importance for sources of informa- tion on endangered species and are of pri- mary interest to conservation groups. The major roles played by a herbarium include: 1. Repository of plant specimens: Pri-

mary role of a herbarium is to store dried plant specimens, safeguard these against loss and destruction by insects, and make them available for study.

Figure 5.10 Patricia K. Holmgren Director Emerita of the Herbarium, New York Botanical Garden, the edi- tor of Index Herbariorum and 2 volumes of Intermountain Flora. (Courtesy New York Botanical Garden, Bronx).

Information updated on 17 February, 2009 from Institutional websites.

* Specimens are located at Laboratoire de Phanérogamie (P) and Laboratoire de Cryptogamie (PC). **Consists of Arnold Arboretum (A), Farlow Herbarium (FH), Gray’s Herbarium (GH), The Economic Herbarium of Oakes Ames (ECON) and Oaks Ames Orchid Herbarium (AMES).

Herbarium Abbr. No. of specimens

1. Museum National d’Histoire Naturelle

(Museum of Natural History), Paris, France* P, PC 9,377,300 2. New York Botanical Garden, New York, USA NY 7,000,000 3. Komarov Botanic Institute, Saint Petersburg

(Formerly Leningrad), Russia. LE 7,000,000

4. Royal Botanic Gardens, Kew, Surrey, UK K 7,000,000 5. Conservatoire et Jardin Botaniques

(Conservatory and Botanical Garden),

Geneva, Switzerland G 6,000,000

6. Missouri Botanical Garden, Saint Louis,

Missouri, USA MO 6,000,000

7. British Museum of Natural History,

London, UK BM 5,200,000

8. Combined Herbaria, Harvard University, A, FH, GH, Cambridge, Massachusetts, USA** ECON,

AMES 5,000,500 9. Naturhistorika Riksmuseet, Stockholm,

Sweden S 4,400,000

10. US National Herbarium (Smithsonian),

Washington, USA US 4,340,000

Table 5.1 Major herbaria of the world, listed in the order of number of specimens.

2. Safe custody of type specimens: Type specimens are the principal proof of the existence of a species or an infraspecific taxon. These are kept in safe custody, often in rooms with restricted access, in several major herbaria.

3. Compilation of Floras, Manuals and Monographs: Herbarium specimens are the ‘original documents’ upon which the knowledge of taxonomy, evolution and plant distribution rests. Floras, manuals and monographs are largely based on herbarium resources. 4. Training in herbarium methods: Many herbaria carry facilities for training graduates and undergradu- ates in herbarium practices, organiz- ing field trips and even expeditions to remote areas.

5. Identification of specimens: The majority of herbaria have a wide-rang- ing collection of specimens and offer facilities for on-site identification or having the specimens sent to the herbarium identified by experts. Re- searchers can personally identify their collection by comparison with the duly identified herbarium specimens. 6. Information on geographical

distribution: Major herbaria have collections from different parts of the world and, thus, scrutiny of the speci- mens can provide information on the geographical distribution of a taxon. 7. Preservation of voucher specimens:

Voucher specimens preserved in various herbaria provide an index of specimens on which a chromosomal, phytochemical, ultrastructural,

micromorphological or any specialized study has been undertaken. In the case of a contradictory or doubtful report, the voucher specimens can be critically examined in order to arrive at a more satisfactory conclusion.

Mounting of Specimens

Pressed and dried specimens are finally mounted on herbarium sheets. A standard herbarium sheet is 29 by 41.5 cm (11½ by 16½ inches), made of thick handmade pa- per or a card sheet. The sheet should be rela- tively stiff to prevent damage during han- dling of specimens. It should have a high rag content (preferable 100 per cent) with fibres running lengthwise.

The specimens are attached to the sheet in a number of ways. Many older specimens in the herbaria are frequently found to have been sewn on the sheets. Use of adhesive linen, paper or cellophane strips is an easier and faster method of fixing specimens. Archer method involves the use of small strips of liq- uid plastic extruded from a container with a narrow nozzle. Most of the contemporary specimens are fixed using liquid paste or glue in one of the two ways, however:

(i) Paste or glue is applied to the backside (if distinguishable) of the specimen, which is later pressed onto the mounting sheet and allowed to dry in the pressed condition for a few hours. This method is slower but more economical.

(ii) Paste or glue is smeared on a glass or plastic sheet, the specimen placed on the sheet and the glued specimen transferred to a mounting sheet. This method is more efficient but expensive. The use of methylcellulose as adhesive mixed in a solution of 40% alcohol, instead of pure water was suggested by Tillet (1989) for fixing herbarium specimens. It decreases the drying time and also prevents growth of micro-organisms. The stem and bulky parts may often require adhesive strips or even sewing for secure fixing of specimens. Small

paper envelops called fragment packets are often attached to the herbarium sheet to hold seeds, extra flowers or loose plant parts.

Labelling

An herbarium label is an essential part of a permanent plant specimen. It primarily con- tains the information recorded in the field diary (Field notebook) at the time of collec- tion, as also the results of any subsequent identification process. The label is located on the lower right corner of the herbarium sheet (Figure 5.11), with the necessary in- formation recorded on the pre-printed pro- forma, printed directly on the sheet or on the paper slips which are pasted on the sheets. It is ideal to type the information. If handwritten, it should be in permanent ink. Ball pens should never be used, as the ink often spreads after some years.

There is no agreement as to the size of a herbarium label, the recommendations be- ing as diverse as 2¾ by 4¼ inches (Jones and Luchsinger, 1986) and 4 by 6 inches (Woodland, 1991). The information commonly recorded on the herbarium label includes:

Name of the institution Scientific name

Common or vernacular name Family

Locality

Date of collection Collection number Name of the collector

Habit and habitat including field notes An expert visiting a herbarium may want to correct an identification or record a name change. Such correction is never done on the original label but on a small annotation label or determination label, usually 2 by 11 cm and appended left of the original la- bel. This label, in addition to the correction, records the name of the person and the date on which the change was recorded. Such information is useful, especially when more than one annotation label is appended to a herbarium sheet. The last label is likely to be the correct one.

Voucher herbarium specimens of a research study often have authentic infor- mation about the specimens recorded in the form of a voucher label.