A key to the grasses (Poaceae) of Egypt: Grasses of Egypt

From Firenze University Press Journal: The Journal of Plant Taxonomy and Geography (Webbia)

Paul M. Peterson, Department of Botany MRC-166, National Museum of Natural History, Smithsonian Institution

Hasnaa A. Hosni, Herbarium, Botany and Microbiology Department, Faculty of Science, Cairo University

Eman K. Shamo, Herbarium, Botany and Microbiology Department, Faculty of Science, Cairo University

The Poaceae (Gramineae) is a large cosmopolitan family with 768 genera and 11,506 species (Soreng et al. 2017). The family includes cereal grasses, bamboos, and species occurring in natural grasslands, cultivated lawns, and pastures. The family has been divided into subfamilies ranging from two (Tzvelev 1989) to six (Clayton and Renvoize 1986), and more recently the family has been divided into 12 subfamilies (Takhtajan 2009; Reveal 2012; Soreng et al. 2017, 2019; Stevens 2017). In Egypt the grasses are the largest family of flowering plants with 284 species belonging to 103 genera and 22 tribes (Ibrahim et al. 2016).

The most comprehensive account of the family in Egypt was done by Täckholm et al. (1941). Other treatments of the grasses of Egypt include Täckholm (1974), Cope and Hosni (1991), Cope (2005), Boulos (2009), and Ibrahim et al. (2016).The identification of grasses is usually based on the structure of the inflorescence and floral characteristics. However, in some cases it is necessary to identify grasses by its vegetative character if the flowers are not available. In such cases the vegetative characters can be used until a flowering specimen is obtained (Hosni and Ibrahim 2004; Ibrahim et al. 2016).

Phylogenetic studies using results from DNA sequences have changed the classification of the grasses and this paper follows the current use of a name as proposed in these papers. With the publication of the grasses of Egypt using a vegetative key (Ibrahim et al. 2016), the need for an updated floral key is apparent. Earlier traditional treatments of the grasses of Egypt, i.e., Cope and Hosni (1991) and Cope (2005) are outdated and it is often difficult to determine the current use name. Our paper presents a new key for the identification of grasses native and adventive in Egypt and is written for use by both trained botanists and interested amateurs. Therefore, we have included an introduction defining many terms used in the key.

The key is designed to facilitate the identification and is simplified as much as possible using characters based on the inflorescence and spikelet. Our key refers only to Egyptian specimens and, in addition, we include a updated classification of all grasses found in Egypt.The accepted names follow the Catalogue of New World Grasses (Soreng et al. 2015, 2017) using terminology found in Kellogg (2015), Clayton et al. (2016), Ibra-him et al. (2016, 2018), and Herrera Arrieta and Peter-son (2018). Because the inflorescence of grasses takes a variety of shapes, it is convenient to group them into categories based on their morphology. Accordingly, the identification key is divided into two parts, a key of major groups based mainly on inflorescence characters followed by keys to the species within each group. Brief descriptions, synonyms, and illustrations of the species was provided in Ibrahim et al. (2016).

DOI: https://doi.org/10.36253/jopt-9004

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