TAXONOMIC AIDS

                TAXONOMIC AIDS

BOTANICAL GARDENS

A botanical garden or botanic garden is a garden dedicated to the collection, cultivation and display of a wide range of plants labeled with their botanical names. It may contain plant collections such as succulent plants, herbs, tropical plants, alpine plants, exotic plants, endemic, rare and endangered plants. There may be herbaria, green houses and shade houses associated with Botanical gardens.

A botanical garden is a controlled and staffed institution for the maintenance of a living collection of plants under scientific management for the purposes of scientific research, conservation, display, and education. It holds scientifically ordered, documented and labeled plants. These are often run by universities colleges or research organizations.

The first garden for the purpose of education and experimentation was set up by Theophrastus in 300bc in lyceum at Athens, credited to him by his teacher Aristotle.

The credit for the establishment of first modern botanical garden belongs to Luca Ghini (1490-1556) at Pisa Italy in 1944.

The botanical gardens play the following important roles and functions;-

• Availability of plants for scientific research
• Display of plant diversity in form and use
• Display of plants of particular regions (including local)
• Plants of economic significance
• Glasshouse plants of different climates
• All plants accurately labeled
• Research facilities utilizing the living collections
• Studies in plant taxonomy
• Examples of different vegetation types
• Student education

Selection and introduction of ornamental and other plants to commerce

• Major botanical gardens 

There are more than 800 botanical gardens listed in the international directory of botanical gardens. Some major botanical gardens are listed as under;-

Botanical garden	Establishment
Pisa botanical garden, Italy	1544
New York botanical garden, USA	1891
Royal botanical garden  kew, KEW	1759
Missouri botanical garden, USA	1859

HERBARIUM

A herbarium is a collection of preserved plant specimens stored, catalogued and arranged systematically for the study and research.

Individual plants or plant parts are preserved in various ways stored and cared over time so that current and future generations can identify plants, study biodiversity and use the collection in support of conservation, ecology and sustainable development.

The art of herbarium making was initiated by Luca ghini. C. linneus mounted the plants on single sheets of paper and stored them horizontally, a practice even followed today.

Steps in making herbaria.

1- Plants are collected.

2- Pressed

3- Mounted on sheets of size 29cm × 41.5cm

4- The mounted sheets are labeled

5- Pest control treatments

6- Storage

Role of herbarium

• These act as repository of plant specimens.
• Type specimens are safe guarded forever.
• Floras manuals and monographs are compiled on herbarium resources.
• Provides facilities for onsite identification of plant specimens.
• Provide information about geographical distribution of plant species.
• Stored plant specimens can be used for DNA extraction.

Major herbaria

Herbarium	Abbreviation	No. of specimens
Museum national de historic naturelle, Paris France	PPC	9.5 million
New York botanical garden herbarium, new York USA	NY	7 million
Royal botanical garden herbarium, KEW UK	K	7 million
Central national herbarium-botanical survey of India, Kolkata India	CAL	1.3 million

TAXONOMIC KEYS

Taxonomic keys are aids for rapid identification of unknown plants. The keys are based on cards, tables and computer programs. These also constitute floras, manuals and monographs as components of literature. the taxonomic keys are meant for the rapid identification of unknown plants. These keys are fundamentally based on characters which are stable and reliable. These keys are helpful in a faster preliminary identification which can be confirmed by detailed study of that taxon.

Based on arrangement of characters and their utilization two types of identification keys are differentiated.

Single access or sequential keys;- these keys are based on diagnostic characters (diagnostic keys) and use pairs of contrasting characters (dichotomous keys). The contrasting characters are mutually exclusive .the two contrasting choices of a pair constitute a couplet and each choice a lead. The arrangement of leads of a couplet can be intended (intended or yocked keys) or parallel (parallel keys).

Multi-access leys or polyclaves;- these are multi-entry order free keys with no predetermined sequence. Small cards are used. One card for one character. The cards can be punched at centre (body punched) against a choice or at edges (edge punched).