Viola sect. Sclerosium  W. Becker      

Section Sclerosium is a mesotetraploid (= That has become tetraploid in more recent history) lineage that contains about seven morphologically close taxa occurring in seasonally dry areas bordering the Indian Ocean and the Red Sea, i.e. northeastern Africa (Egypt, Sudan, Eritrea, Somalia), Arabia (Saudi Arabia, Yemen, Oman, United Arab Emirates) and southern Iran to western India (Becker 1918, 1925; Gilbert 1992) (Figure 1). Members of sect. Sclerosium can be recognized by their particular dorsiventrally bilobate style, chasmogamous flowers having both yellow and purple pigmentation and a short ± saccate spur, the often copious occurrence of cleistogamous flowers, and vegetatively by the relatively narrow leaves basally attenuate into an ill-defined petiole, and the narrow ± entire stipules. The taxa of sect. Sclerosium are apparently closely related and differ especially in pubescence, from glabrous to densely pubescent, and in longevity, from ephemeral to woody perennial. Apart from preliminary revisions by Becker (1918, 1925) and by Gilbert (1992), a formal taxonomic revision of sect. Sclerosium is still lacking. It is currently unclear whether to recognize the many ecotypes and morphotypes as separate species (e.g. Becker 1925) or as subspecies or varieties all within V. cinerea Boiss. (Becker 1918; Gilbert 1992). In Iran, sect. Sclerosium is represented by three taxa in the southern region, the endemic Viola behboudiana Rech. F. & Esfand. (syn.: Viola makranica Omer & Qaiser), and the more widespread Viola cinerea s.str. and Viola stocksii Boiss. Outside Iran V. cinerea s.str. is reported only from the immediate neighbouring regions of Pakistan (Makran District) and Arabia (Oman: Ru’us al-Jibal, Djebel Akhdar; United Arab Emirates: Hajjar mountains). Endemic morphotypes, or separate species (Becker 1925), exist in northeastern Africa, var. erythraea Fiori in Eritrea and var. somalensis (Engl) Chiov in Somalia (Omer and Qaiser 1985; Gilbert 1992). Viola stocksii Boiss. [syn.: V. cinerea subsp. kathiavrensis W. Becker, V. cinerea var. stocksii (Boiss.) W. Becker] extends from the southern region of Iran into Pakistan, India and Afghanistan (Omer and Qaiser 1985; Khatamsaz 1991). The type specimens of V. cinerea, V. stocksii and V. behboudiana are from Oman, Pakistan and Iran, respectively (see Figure 1). Viola behboudiana and V. cinerea were considered as synonyms by Schmidt (1992) and as distinct species by Khatamsaz (1991). Delimitation of these closely related taxa, and the section as a whole (Gilbert 1992), is problematic when using only morphological characters, and a detailed anatomical study is required. In most identification keys, annual form, glabrous capsules, stipules and peduncles are considered as crucial characters for distinguishing V. behboudiana and V. stocksii from V. cinerea, which is perennial and densely pubescent all over .

1. Becker, W. 1918. “Violae Asiaticae et Australenses.” Beihefte zum botanischen Centralblatt, Abt. ΙΙ, 36: 15–59. 

2. Becker, W. 1925. “Viola L.” In Die natürlichen Pflanzenfamilie. Vol. 21. Parietales und Opuntiales, edited by A. Engler, 363–376. Germany: Wilhelm Engelmann 

3. Gilbert, G. M. 1992. “Notes on Violaceae from Ethiopia.” Nordic Journal of Botany 12: 689–693 

4. Khatamsaz, M. 1991. Flora of Iran, Violaceae, vol. 5, 1–50. Ministry of Jahad-Sazandegi, Research organisation of Agriculture and Natural Resources, Research Institute of Forests and Rangelands. 

5. Omer, M., and S. Qaiser. 1985. Flora of Pakistan: Violaceae. vol. 166. Department of Botany: University of Karachi. 

6. Schmidt, A. 1992. “Violaceae”. In: Flora Iranica, edited by K.H. Rechinger, K. H., 169:1–29, Graz: Akademische Druck- und Verlagsanstalt 

7. From: Maryam Mohammadi Shahrestani, Shahryar Saeidi Mehrvarz, Thomas Marcussen & Narjes Yousefi. Taxonomy and comparative anatomical studies of Viola sect. Sclerosium (Violaceae) in Iran. Acta Botanica Gallica Botany Letters Volume 161, 2014 - Issue 4