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It is a monotypic or unigeneric family represented by four genera containing about 91 species distributed mainly in north-east Australia and also in Fiji, New Caledonia, Malaysia and Mascarene islands. Only one species (Casuarina equisetifolia) occurs in India, and this is the most common species of the world.
Selected Genera
Casuarina, Gymnostoma, Allocasuarina, Ceuthostoma.
Economic Importance
Casuarina is important mainly as timber tree. The wood of C. equisetifolia, C. cunningbamia and C. stricta is used for furniture, for fuel and also for basket making. The bark of C. suberosa and C. stricta is utilized for tanning. C. equisetifolia is usually grown as an ornamental and also in order to reclaim sandy dunes in India and several countries.

It is represented by about 100 genera and over 2,200 species which are either annual or perennial, Caryophyllaceae are cosmopolitan in distribution, and mainly found in the north temperate or warm temperate regions of the world. Over 20 genera and about 100 species have so far been reported from India. Some of the larger genera, along with their common names and number of species in parenthesis include Silene (catchfly, 500), Dianthus (carnation, 300), Arenaria (sandwort, 250), Gypsophila (baby’s breath, 125), Stellaria (chickweed, 100), Cerastium (mouse-ear chickweed, 100), Drymaria (50), Spergula (40), Saponaria (30), etc.
Carnation, commonly named as ‘Divine flower’, ‘Clove pink’, and ‘Gilly flower’, is one of the most beautiful and commercially important flower crops of the world. It is excellent for cut flowers, bedding, pots, edging and rock gardens due to its exquisite shape, wide range of colours, light weight and good vase life. In Europe and USA, perpetual carnation is cultivated on large scale in greenhouses for production of cut flowers. In terrain parts of France and Holland, carnation flowers are used for perfume extraction and only light coloured flowers are useful for this purpose.
Description of Family
1. General habit: Mostly annual or perennial herbs, rarely suffrutescent shrubs; arctic forms are reduced and possess caespitose habit.
2. Stem: Herbaceous; rarely with a basal woody part; nodes swollen; branching usually dichotomous but sometimes monopodial.

Cacti are eulogized as ‘Plants of 21st century’. They have gained popularity due to many exciting shapes, blooms, ease of culture and long life without least care. Cacti are categorized as fleshy stem succulent with photo-synthetically active stem. Good for indoor decoration in pot, outdoor decoration, landscaping, public garden, rock garden, etc.
The family Cactaceae includes approximately 131 genera and 1,750 species. But different authors mention the number of genera differently between 30 to 200. Members are distributed chiefly in semi-desert or drier regions of tropical and sub-tropical America, and also in Africa, Mauritius, Seychelles, India, Sri Lanka and Australia. Mainly the Cactaceae are the succulents of New World. Main species of Old World is Rhipsalis. Some of the larger genera along with their number of reported species are Mammillaria (200-300), Opuntia (250), Echinocereus (75), Rhipsalis (60), Cereus (50), Cephalcereus (48), Echinopsis (35), Epiphyllum (21) and Pereskia (20).
The classification of the family Cactaceae remains uncertain as of August 2023. Since the mid-1990s, the system produced by the International Cactaceae Systematics Group (ICSG) of the International Organization for Succulent Plant Study has been used as the basis of many published classifications. Hunt (2006) recognized Cactaceae family has 4 sub-families viz. Pereskioideae (the leaf cactus, 20 spp.), Opuntioideae (300 spp.), Cactoideae (1,000 spp.) and Maihuenioideae (2 spp.). Three tribes: Pereskieae, Opuntieae, Cereae. Tribe Cereae has 8 sub-tribes: Cereanae, Hylocereanae, Echinocereanae, Echiocactanae, Cactanae, Coryphanthanae, Epiphyelanae, Rhipsolidanae. The cacti of sub-tribe ‘Echinocereanae’ are commonly known as ‘Hedgehogs’.

Genome editing has emerged as a powerful tool for accelerating crop improvement in horticultural crops by enabling precise modifications in their genetic architecture. Considering the development and advantages of genomeediting technologies in improving diverse characteristics of horticultural crops, substantial increase has been reported in recent years including ZFN, TALEN, and especially CRISPR/Cas systems. The CRISPR/Cas technology has proved its potential in altering many genes of interest in horticultural plants including fruits, vegetables, and ornamental plants for improving agronomically important traits and attributes such as growth rate, seed size, flowering time, flower color, storage time, resistance to biotic stresses, tolerance to abiotic stresses, herbicide tolerance, metabolism, fruit color, fruit ripening etc. This technology opens new avenues for more favorable and precise manipulation of plant genomes to improve crop performance.
Genome editing has emerged as a powerful biotechnological tool with transformative potential for horticultural crops. It involves the precise modification of plant DNA to enhance desired traits, increase crop yield, and confer resistance to pests, diseases, and environmental stresses. Molecular tools like CRISPR-Cas9, TALENs, and ZFNs act as molecular scissors, allowing for the targeted alteration of specific DNA sequences with unprecedented accuracy. This technology allows scientists to introduce or enhance beneficial traits in crops, including disease resistance, improved nutrition, and drought tolerance. Horticulture is a critical component of global food production and human well-being as it involves cultivation and management of plants for food, aesthetics, and medicinal purposes. Horticultural crops comprising fruits, vegetables, ornamental plants, and medicinal herbs, not only contribute to nutritional needs of populations worldwide but also enhance the visual appeal of our surroundings. However, productivity and quality of horticultural crops face significant constraints due to challenges such as biotic and abiotic stresses, limited genetic variation, and increasing demands for improved traits. Plant breeders have employed various techniques, such as hybridization, selection, and genetic manipulation, to enhance horticultural crops. These approaches have contributed to improved yield, disease resistance, and other desirable traits.

Represented by about 120 genera and over 800 species. Bignoniaceae are distributed mainly in tropical and sub-tropical, and a few in temperate regions. About 15 genera and 40 species are found in India. Some of the larger genera along with their approximate number of worldover reported species are Tabebuia (100), Arraabidaea (70), Jacaranda (50), Anemopaegma (30), Tecoma (16), Catalpa (11) and Crescentia (5).
Selected Indian Genera
Jacaranda, Kigelia, Millingtonia, Tecoma, Heterophragma, Oroxylum and Dolichandrone. Economic Importance
1. Ornamental plants of the family include handsome trees (Catalpa bignonioides, Haplophragma adenophyllum, Jacaranda mimosaefolia, (Fig. 26.1), Kigelia pinnata, Millingtonia hortensis, Spathodea campanulata and Tabebuia spectabilis), shrubs (Bignonia unguis-cati), beautiful tendril-climbers (Adenocalymna alliaceum, Bignonia venusta syn. Pyrostegia venusta), aerial rootlet climbers (Campis grandiflora and C. radicans) and herbaceous genus Incarvillea.

With the advent of clustered regularly interspaced short palindromic repeat (CRISPR)-associated protein9 (CRISPR/Cas9) genome editing, a fast and efficient new breeding technology, precision breeding in vegetable crops has become possible now. Several genes have been edited and functionally characterized using CRISPR/Cas9 in tomato for multiple traits such as plant type, floral morphology, fruit traits, disease resistance, and abiotic stress tolerance. The CRISPR/Cas9 has been proven in successful introgression of de novo domestication of elite traits from wild relatives to cultivated tomato. The progress in CRISPR/Cas9 based improvement in vegetable improvement, has been discussed.
Vegetables are an important source of healthy diet, as they provide essential nutrients including vitamins, minerals, dietary fibre, antioxidants and other phytochemicals. Dietary fiber-rich vegetables improve digestion, while also lowering the risk of obesity, diabetes, high cholesterol and heart disease (Behera et al., 2021). A world vegetable survey showed that around 392 vegetable crops are cultivated worldwide, representing 70 families and 225 genera. Over 97 species of higher plants are being cultivated and consumed as vegetables in India. These crops belong to 20 different families such as Cucurbitaceae (25 crops), Fabaceae (16 crops), Brassicaceae (12 crop) and Solanaceae (6 crops). The world’s total vegetables production was 1,155 million tonnes in 2021 where China ranks first with a total production of 600 million tonnes, accounting for 52.18% of the total world production. The top 5 countries (China, India, the United States of America, Turkey and Vietnam) account for 70.36% of total world’s production. As far as India is concerned,  it is the largest producer of ginger (2.23 million tonnes) and okra (6.47 million tonnes) in the world, while ranking 2nd in potato (54.23 million tonnes), dry onion (26.64 million tonnes), cauliflower and broccoli (9.25 million tonnes), brinjal (12.87 million tonnes) and cabbage (9.56 million tonnes) (FAO 2023).

Asteraceae or Compositae is one of the largest families of flowering plants, represented by about 1,707 genera and over 23,600 species which are worldwide in distribution. Radford (1986) has mentioned the number of genera to be ‘One thousand to 2000’. About 140 of its genera and over 700 species have been reported from India. Some of the largely represented genera include Senecio (2,000+), Eupatorium (1,200), Vernonia (1,000), Hieracium (1,000), Centaurea (600), Aster (500), Helichrysum (500), Cousinia (400), Artemisia (400), Baccharis (400), Mikania (250), Bidens (230), Crepis (200), Inula (200), Erigron (200), Chrysanthemum (160), Cirsium (150), Ligularia (150), Helianthus (110), Lactuca (100), Hypochoeris (100) and Carduus (100).
In the Chrysanthemum genus, the modern autumn flowering perennial Chrysanthemum morifolium Ramat is most important. The name of C. morifolium Ramat has been changed to Dendranthema grandiflora Tzvelev (Anderson, 1987; Heywood and Humphries, 1977 and Kitamura, 1978). Chrysanthemum (D.x grandiflora) is an internationally recognized floriculture crop. It ranks second among commercial flowers in the international market. It is known as ‘Queen of East’ in Japan while in USA, it is considered as the ‘Queen of the fall flowers’. Flowers are in great demand in landascape, for making garland, wreath, veni and religious offerings. Pot chrysanthemums are
commonly known as ‘mums’ and large flowered cultivars are used as potted plants.

A family of 140 genera and over 4,075 species, Araceae are distributed mostly in tropical and some also in temperate regions of the world. About 25 genera and over 140 species have been reported from India, chiefly from western and southern parts. Some larger genera along with the number of their worldover reported species are Anthurium (500), Philodendron (275), Arisaema (150), Amorphophallus (100), Rhaphidophora (100), Pothos (75), Alocasia (70), Monstera (50), Arum (15), Colocasia (8), Acorus (2) and Pistia (1). Colocasia (Colocasia antiquorum) and ‘money plant’ (Pothos aureus) are two famous plants of Araceae.
Anthurium is a beautiful group of tropical aroids. It is cultivated globally for its attractive flowers and foliage. The flowering stalks have a long vase life and add an ethnic beauty to any floral decoration. Anthurium also called as ‘Flamingo flower’ or ‘Boy flower’, both referring to the structure of the spathe, and spadix. ‘Anthra’ is a worldwide knowledge center for the cultivation of anthurium, based on Holland and Germany. ‘Anthura’ performs activities in the field of research and development breeding, tissue culture technology, training and publishing cultivation know- how. ‘Anthura’ collaborates with research stations and test locations in Thailand, China, USA, Japan and India.

A family of about 400 genera and 4,555 species of mostly tropical and subtropical distribution, but a few species distributed also in temperature regions. About 30 genera and over 60 species of Apocynaceae have been reported from India. Some of the larger genera along with their approximately reported species in bracket are Rauvolfia (100), Tabernaemontana (100), Parsonsia (100), Aspidosperma (80), Prestonia (65), Strophanthus (60), Apocynum (7), Plumeria (6) and Catharanthus (5). Some plants are of medicinal value and some are highly ornamental.
Periwinkle (syn. Vinca) is grown as an ornamental bedding plant in gardens and parks and is known for its colourful flowers and ever-blooming nature. In India, it is commonly known as sada bahar, sada phuli, and barmasi. It is one of the top ten best selling plant in USA. Its importance has increased owing to medicinal properties and as a model species for study of plant’s secondary metabolism. The plant contains more than 70 different alkaloids in leaves and roots which contribute to anti-cancerous (vincristine and vinblastine) and antihypertensive (ajamalicine) properties, respectively.

Fruits contribute to nutritional security and thus are an important part of food system. To meet the future demand, development of varieties with improved yield and quality is the focus of researchers involved in fruit breeding. Though conventional breeding has resulted in the development of improved commercial varieties of different fruit crops, however conventional breeding is time consuming and faces several challenges due to long juvenile phase, highly heterozygous nature of most of the fruit crops. Challenges like changing climate, consumer preference, socio-economic conditions like reduced availability of land, labour and increasing cost of inputs, require fast and efficient methods to develop the varieties to meet the demands, which is not feasible with conventional breeding. Marker assisted breeding has given impetus to breeding efforts in several fruit crops, however it’s use is limited only for the traits controlled by a few major QTLs.
During last few years, enormous genomic resources have been developed for fruit crops using next generation sequencing technology. Such advances in genomic research in many fruit crops have paved the way for precision breeding using genomic assisted breeding (GAB) tools. GAB has helped in characterisation and utilisation of genome resources and using allele variation for cultivar development (Varshney et al. 2021). Advances in sequencing technology and affordability has allowed the genome wide analysis (GWAS) on diversity panels of different fruits resulting in identification of allelic variation associated with the traits of interest. Also, identification of superior alleles of candidate genes makes them amenable to genome editing based precision breeding. Genome wide genotyping and phenotyping offers tools for developing strategy for genomic selection (GS). Genomic selection relies on the prediction of breeding values of tested genotypes based on the large number of markers spread over entire genome. These tools promise to further improve breeding efficiency in fruit crops.

A family of about 73 genera and over 1,600 species (Hickey and King, 1988),Amaryllidaceae are usually distributed in tropical and sub-tropical regions. About 9 genera and over 60 species have been reported from India. Some of the larger genera along with the number of their world over reported species are Crinum (110), Hippeastrum (75), Narcissus (60), Hymenocallis (50), Haemanthus (50), Cyrtanthus (47), Zephyranthes (40), Galanthus (20), Polianthes (15), and Pancratium (15).
Hippeastrum (popular name Amaryllis) is one of the most beautiful bulbous ornamental plants grown in the world. It is very suitable for planting in pots, greenhouses, window gardens, flowering beds, rockeries, popular as cut flower, and useful in floral arrangements. Hippeastrum and Amaryllis are synonyms for ‘Trumpet lily’ or ‘Night Star lily’ in Indian gardens. In USA, A. belladonna is known as Callicore rosea sometimes as Hippeastrum equestre, and in South Africa as ‘March lily’, being a variable species. Plants of the genus A. belladonna are known as ‘Belladonna lily’, ‘Naked Lady’ or ‘Amarillo’. Hippeastrum hybridum is popularly known as ‘Royal Dutch’ amaryllis or ‘Dutch’ amaryllis hybrids. Hippeastrum takes its name from the Hippeus meaning ‘a knight rider’ or horse and ‘astron’ meaning a star, due to some fancied resemblance in H. equestre, perhaps of the equitant leaves and the star shaped corolla opening.

A family of about 175 genera and 2,500 species, Amaranthaceae are mostly distributed in tropical but also in temperate regions. About 18 genera and over 50 species have been reported from India. Some of the larger genera with the number of their approximately reported species and common names are Alternanthera (200, alligator weed), Gomphrena (100, globe amaranth), Iresine (80, gizzard plant), Amaranths (60, pigweed) and Celosia (60, cock’s comb).
Gomphrenas are 30-40 cm tall, bushy with erect stems, hairy, light green with oblong-ovate leaves tapering towards the base. Round button like or spherical flower head is a cylindrical spike 1-2 cm long and 1 cm in diameter and may be terminal and/or axillary, and are born on long, thin stems above the foliage. Each flower head has tiny, conspicuous, papery, colourful bracts which enclose the inconspicuous true flowers. Bracts ovate, three mm long, apex acuminate, bracteoles 4.5-5.5 mm long. Ovary is sub-globose with two stigmas. Seed is brown, lustrous, 1.5 mm long (Wagner et al., 1999). It has both C3 and C4 pathway.
Selected Indian Genera
Achyranthes, Alternanthera, Amaranths, Celosia, Digera, Gomphrena and Pupalia.

DUS testing is a way of determining whether a newly bred variety differs from existing varieties within the same species, or the characteristics used to establish distinctness are expressed uniformly and that these characteristics do not change over subsequent generations. Testing the distinctness, uniformity and stability (DUS) of crop varieties is a statutory requirement before varieties can be entered into the Registers of Cultivars (National Lists) and/or granted Plant Breeders’ Rights (PBR). In India, Protection of Plant Varieties and Farmers’ Right (PPV&FR) Act (2001) provides the registration of new variety of plant if it conforms to the criteria of distinctness, uniformity and stability.
Why do we need a DUS test? New (candidate) varieties should be distinct from all other varieties whose existence is a matter of common knowledge, and also sufficiently uniform and stable with respect to the characteristics used to demonstrate distinctness. ‘Common knowledge’ is broadly defined to include all known varieties, i.e. any variety entered into or subject to an application for PBR, varieties grown commercially, held in publicly accessible reference collection, or of which there is a published description (UPOV 2002).
The responsibility for DUS testing of potato varieties in India lies with the ICAR-Central Potato Research Institute (CPRI), Shimla, which is the national institute for potato research and development. Currently a set of 51 DUS characters in potato are defined by CPRI and being used for distinguishing new variety.

A family of over 250 genera and 2,500 species, Acanthaceae are distributed mainly in tropics, but also in Mediterranean region, Australia and USA. Central America, Brazil, Africa and Indo-Malaysia are the 4 chief centres of
distribution. About 70 genera and over 340 species have been reported from India. Some of the largely represented genera along with the approximate number of their worldover reported species are Justicia (300), Strobilanthes
(250), Barleria (230), Thunbergia (200), Aphelandra (200), Decliptera (150), Blepharis (100), Staurogyne (80), Mendoncia (60), Crossandra (60) and Acanthus (50).
Selected Indian Genera
Acanthus, Adhatoda, Barleria, Eranthemum, Justicia, Peristrophe, Ruellia, Thunbergia.
Economic Importance
1. Ornamental plants include Aphelandra aurantiaca, Barleria cristata, B. gibsoni, Beloperone guttata (shrimp plant), Crossandra infundibuliformis, Eranthemum bicolor, E. nervosum, Fittonia gigantea, Jacobinia carnea, Justicia gendarussa, Ruellia brittoniana, Thunbergia coccinia, T. erecta, T. fragrans and T. grandiflora.

The potential of Vegetable Genetic Resources (VGR) is vast, offering solutions to future challenges such as food and nutritional security. Achieving this requires the identification, collection, conservation, documentation, and utilization of these resources. The introduction and acceptance of improved varieties have resulted in the replacement of numerous landraces and local crop cultivars across various agri-horticultural crops, with a particular impact on vegetables. The alignment of activities related to the management of plant genetic resources at both global and national levels has enhanced the opportunities for utilizing VGR. India possesses a rich diversity of vegetable genetic resources, comprising indigenous and exotic varieties. Information regarding VGR in the Indian region can be accessed through passport data, conservation records, catalogs detailing characterization and evaluation, as well as insights into local vegetable usage, all of which contribute to strengthening these initiatives. This chapter delves into vegetable genetic resources, focusing on economically significant vegetable crops of India, along with regionally important crops, potential species, and their wild relatives, highlighting efforts undertaken at ICAR, NBPGR for its collection conservation, characterization and utilization.

Agriculture including forestry, range management and sustenance of plant biodiversity have been the core of Indian civilization that dates back to several millenniums. The enormous plant diversity arising due to the varie soil, environment and altitude variations that India enjoys has resulted in the evolution of various crop species and varieties suiting to different domestic and commercial needs. The Gene Fund created under the law is designed to encourage, protect, promote, and utilize the plant biodiversity for plant
breeding activity in perpetuity. The Gene Fund in turn gets nourished by the flow of annual fee arising out of the sale of seed of the registered varieties. The keepers (services of the men and women; individuals and communities) of plant variation in the agrobiodiversity hotspots are to be beneficiaries of the gene fund. National Gene Fund shall be used for supporting and rewarding farmers and farming communities, who are engaged in conservation and improvement of genetic resources of economic plants and their wild relatives, particularly from the areas identified as hotspots of agrobiodiversity.
An understanding of intellectual property rights for plant breeders has become increasingly important over the last few decades. It is also a confusing topic to many in the industry. Confusion is understandable when we are presented with various types of protection, many acronyms, terms used interchangeably and incorrectly, regulations that vary internationally and a lack of understanding or consistent interpretations of laws that govern these rights.

Demand-driven vegetable breeding emphasizes the development of new cultivars based on specific consumer preferences, market demands, and environmental conditions. This approach contrasts with traditional breeding methods that primarily focus on agronomic traits like yield or disease resistance. The importance of demand-driven breeding lies in its ability to align agricultural production with consumer needs and market trends. By directly responding to consumer preferences such as taste, appearance, nutritional content, and culinary characteristics, breeders can create vegetables that are not only commercially viable but also meet consumer expectations. This approach enhances market acceptance and profitability for growers, distributors, and retailers alike. Breeders prioritize demand-driven breeding to stay competitive in a rapidly evolving market where consumer preferences can shift quickly. By understanding and responding to these preferences, breeders can develop cultivars that offer distinct advantages over existing varieties, leading to increased market share and improved economic outcomes for stakeholders throughout the supply chain. This chapter provides an understanding on demand-driven vegetable breeding, particularly opportunities, and challenges.

The science that includes classification, nomenclature and identification of plants is called plant taxonomy. Taxa (Sing. Taxon):A general term for taxonomic classification, irrespective of rank.
18.1 Plant Types (habit and habitat)
1. Annual: A plant that completes its entire life cycle, from seed to reproduction to death, in one single year.
2. Biennial: A plant that completes its entire life cycle in two years.
3. Perennial: A plant that grows and reproduces for many years.
4. Monocarpic: plants that flower and set seeds once during its lifetime. They flower only after attaining maturity. They flower gregariously in a single season e.g. Bamboo and Kurinjis.
5. Polycarpic: Plants that flower and set seeds many times during its lifetime.
6. Aquatic: Organisms growing in water.
7. Shrub: A much branched, small, woody perennial plant with several branches from ground level upwards.
8. Tree: A tall, woody, perennial plant with a single trunk which usually bears branches.

Taxonomy, also known as systematics, is the study of classifying organisms into logically related groups. Historically, taxonomy was performed by examining physical characteristics of organisms and classifying species based on the most commonly held traits. Unfortunately, this method of classifying plants and animals assumes that because they share physical characteristics, they must have shared ancestors. Markers are used over the years for classification of plants. Markers are any trait(s) of an organism that can be identified with confidence and relative ease, and can be followed in a mapping population. They can be defined as heritable entities associated with the economically important trait under the control of polygenes. Molecular markers are any kind of molecule indicating existence of a chemical or a physical process. Molecular markers include biochemical constituents (e.g. secondary metabolites in plants) and macromolecules (e.g. proteins and deoxyribo-nucleic acid). These macromolecules show easily detectable differences among different strains of a species or among different species.
The prerequisite for the improvement of any plant species are germplasm collection and its characterization to find out the diversity among the accessions. Characterization can be done by several ways which include morphological, enzymatic and genetical methods. The best way to assess the diversity is based on DNA markers which allow differentiation among genotypes without any environmental influences. These markers have a great potential to identify genetic diversity within and among accessions which help in successful implementation of pre-breeding approaches. Molecular
markers are considered the best tools for determining genetic relationships diversity as they are unlimited in number, show high polymorphism, provides more reliable information, detect more variation than morphological and biochemical markers; and are stage independent, not affected by environment and simply inherited. Molecular markers are ‘tags’ that can be used to identify specific genes and locate them in relation to other genes. They help in ensuing a desired beneficial trait to be maintained or an undesirable trait to be eliminated.

Collection and conservation of genetic resources in horticultural crops is very much essential in regions where local seed sources are still used in genetic enhancement and cultivar production. Domesticated crops grow well adapted to both tropical and temperate regions. In particular, if the crop is domesticated over centuries to be grown in different latitudes, the genetic diversity estimates are essential for a breeder to develop location specific cultivars. Genetic ulnerability, erosion and extinction of some wild progenitors and species has been altered, warranting the need for ex situ conservation measures. The material is conserved in various forms, ranging from botanical gardens, clonal and seed populations, vegetative methods, in vitro active repositories, pollen cryobanks and DNA banks. The objective, in genetic resource context, is to conserve for prolonged duration with minimal loss of viability and genetic diversity. Most ex situ conservation methods are technology dependent. Seed and pollen banks are dependent in refrigeration technology and cryogenic technology.
The conservation of plant genetic resources in ornamental species is generally driven by demand, focusing on preserving a wide range of genetic diversity. This diversity can include individual genes and coadapted gene complexes at the micro level, as well as entire genotypes, elite clones, and plant populationsat the macro level. The distribution of genetic diversity (GD) in plant species  is predominantly dependent on the reproductive mechanisms they adopt and the mode of inheritance of the characters targeted for collection. The main reasons for collection and conservation genetic resources of an ornamental species gene pool in a given ecosystem are: