Agriculture is one of the fundamental activities for humans, ensuring the production of food essential for the survival and quality of the population’s lives. It forms the foundation of food security in terms of quantity and quality, as well as human and animal health and well-being [1] . In Senegal, agriculture is a key sector of the economy, contributing up to 15% of the country’s gross domestic product [2] . Within this sector, urban agriculture plays an important role by ensuring food supplies for cities, while also creating jobs, generating income, and improving the living environment [3] . Bringing together various activities located within or on the outskirts of cities, urban agriculture encompasses urban forestry, landscape architecture, and market and ornamental horticulture [4] . These practices, particularly ornamental horticulture, are becoming increasingly important in the face of the scarcity of agricultural land in cities and the disappearance of forests, prompting populations to recreate green spaces in order to improve their living environment [5] . Consequently, ornamental horticulture goes beyond simply decorating our living environments; it is a vital sector that combines aesthetic interests with socio-economic and environmental benefits, while contributing to the sustainable development of regions. In Senegal, despite the expansion of horticultural stations, the floristic diversity of ornamental gardens and their main potential remain poorly documented [6] . It is therefore important to deepen our knowledge of ornamental species in order to optimize their use, improve their management, and maximize their benefits. In this context, this study was conducted to characterize the ornamental flora of Saint-Louis city. Specifically, it aims to establish the taxonomic and biological spectra of the recorded ornamental species, identify their main uses, and determine the most valued decorative plant organs.

The inventory of Saint-Louis’s ornamental flora revealed a diverse range of species composed of 134 species belonging to 114 genera and 58 families. Although this inventory was carried out on only 19 horticultural stations, it shows a greater floristic diversity than that reported by [6] , whose work was carried out on 59 horticultural stations in Dakar city and recorded 109 species gathered in 81 genera and 39 families. This variation in species richness could be attributed to farm size. In Dakar, farms are often small and located along roadsides [6] , whereas in Saint-Louis, horticultural developments are on average larger. However, the ornamental flora of Saint-Louis remains less rich than that of Togo, inventoried by [13] , who counted 612 species grouped into 246 genera and 72 families, that of southern Benin inventoried by [14] , with 161 species belonging to 129 genera and 56 families, and that of the city of Nairobi, which inventoried 638 species in 100 green spaces [15] . These dissimilarities can be explained by the number and size of the horticultural sites explored, as well as the development of ornamental activities in cities. Analysis of the flora shows a clear dominance of Angiosperms (93%) over Gymnosperms and Pteridophytes. Within the Angiosperm group, dicotyledons contribute over 64% of species, outnumbering monocotyledons. These proportions are similar to those obtained by [13] , listing 59% dicotyledons and 41% monocotyledons, and those obtained by [6] , with 68.81% dicotyledons versus 23.85% monocotyledons. The results also highlight seven main families: Arecaceae, Lamiaceae, Apocynaceae, Euphorbiaceae, Acanthaceae, Araceae, and Asparagaceae. Of the seven families, three (Apocynaceae, Euphorbiaceae, and Araceae) are confirmed by [16] , which demonstrates their importance in beautifying public spaces. This dominance could be attributed to a better adaptation of the species to diverse biotopes [17] . In addition, various factors could explain this domination. Firstly, the multiple uses of the species, particularly in the Arecaceae and Lamiaceae families. Other factors relate to ease of dissemination, particularly Euphorbiaceae and Apocynaceae, which multiply easily by cuttings, while Araceae and Asparagaceae reproduce by shoots or stump splinters.

In terms of biological types, the results show a primacy of perennial species (95.52%) in the flora surveyed. The most representative biological types among these are Phanerophytes (34.33%), Nanophanerophytes (25.37%), Hemicryptophytes (16.42%), and Chamephytes (10.45%). This finding can be explained by the multiple uses of woody species, in addition to their ornamental role, for food, fodder, and shade. These conclusions are similar to those of [6] , who reported that in floriculture, perennial species are of ornamental but also useful importance.

Concerning species use, the study indicated that 41.79% of species are exclusively dedicated to ornamentation. However, a significant proportion of species combine their aesthetic role with other uses, especially traditional medicine (28.36%), human food (4.48%), animal feed (5.22%), and industry (2.99%). These results underline the diversity of the virtues of ornamental species, as well as their importance within local communities. The majority of plants used for medicinal purposes belong to the Lamiaceae, Verbenaceae, and Rosaceae families, which are known for treating various digestive, respiratory, and genitourinary ailments [18] . Their uses are based on a long-standing tradition of local communities using plants for primary healthcare, reinforced by the high cost of modern medicines [19] . Ornamental plants used for human food are mainly fruit plants (Anacardiaceae, Annonaceae, and Sapotaceae) and aromatic plants (Lamiaceae, Zingiberaceae) used as condiments or spices, while those for industrial purposes are used in carpentry and brewing [20] .

For decorative organs, 61% of ornamental plants have attractive foliage or habit, 29% have decorative flowers, and 10% combine foliage and flowers. These results are similar to those of [21] , who reported that in their work, 50.82% had decorative foliage and 27.13% decorative flowers. The importance of plants combining foliage and decorative habit would be explained by the conservation of their leaves, but also their aesthetic appeal. Among these plants are species of the genera Terminalia, Ficus, Ravenala, and Annona, which are valued for their foliage. While the Apocynaceae, Rosaceae, Malvaceae, Rubiaceae, and Plumbaginaceae families are mainly made up of species with decorative flowers. Plants combining foliage and flowers belong mainly to the Araceae family, offering year-round aesthetic appeal. These observations are similar to those of [22] , finding that combining contrasting colors of plants’ decorative parts and plant habit in landscaping highlights focal points and improves both the aesthetics and physical perception of the area.

This study characterized the ornamental flora of the city of Saint-Louis, indicating a floristic diversity of 134 species grouped into 114 genera and 58 families. Of these, seven main families stand out: Arecaceae, Lamiaceae, Apocynaceae, Euphorbiaceae, Acanthaceae, Araceae, and Asparagaceae. The biological spectrum shows a large majority of Phanerophytes followed by Nanophanerophytes. In terms of species use, species are used exclusively for ornamental purposes, followed by medicinal purposes and human food. Three decorative elements are particularly appreciated, namely decorative foliage and habit, followed by decorative flowers and decorative foliage and flowers. This characterization remains a useful basis for better knowledge, management, and enhancement of the ornamental flora of Saint-Louis in Senegal.