Document Details
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Document Type |
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Thesis |
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Document Title |
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Taxonomic Revision of the Genus Plectranthus L. (Lamiaceae) in Saudi Arabia. مراجعة تصنيفية لجنس الشار (العائلة الشفوية) في المملكة العربية السعودية |
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Subject |
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Biological |
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Document Language |
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Arabic |
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Abstract |
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The genus Plectranthus L. is a member of the family Lamiaceae (Labiatae). The genus Plectranthus is include about 300 species, widespread in Africa (specially in South of the Sahara), South of Arabian Peninsula, India to Australia. About seven species are growing in the western and southwestern regions of Saudi Arabia, which are distributed through the high mountains Plectranthus species resemble morphologically, that the confusion on their identification can be drown moreover identification of some species are doubtful. The aim of the present work is to do morphological; comparative anatomical and chemotaxonomical studies of Plectranthus species growing in Saudi Arabia. The study includes the morphological description of the Plectranthus species and studying the anatomical structures of stems, leaves and petioles, in addition to doing chemotaxonomical investigation of flavonoides compounds in the leaves of Plectranthus arabicus, P. asirensis, P. barbatus, P. cylindraceus, P. lanuginosus, P. pseudomarrubioides and P. tenuiflorus. The results of the morphological features of the studied species show the presence of important characters, which can be used for dividing Plectranthus species into two groups: The first group can be distinguish by non-branching terminal inflorescence which consists of P. arabicus, and P. asirensis. Plectranthus asirensis characterized by the ovate and serrate leaves, violet calyx with an acuminate rounded tip of lower lip teeth and bluish violet corolla, whereas P. arabicus has Obtirullate and dentate leaves, greenish calyx with an acuminate acute tip of lower lip teeth and bluish corolla. The second group includes: P. barbatus, P. cylindraceus, P. lanuginosus, P. pseudomarrubioides and P. tenuiflorus. Which are characterized with the terminal and auxiliary branching inflorescence. This group divided into two sub-groups based on the position of the inflorescence: the first sub-group consists of P. pseudomarrubioides which can be distinguish by the occurrence of both terminal and auxiliary inflorescence; whereas the second sub-group includes P. barbatus, P. cylindraceus, P. lanuginosus and P. tenuiflorus which their inflorescence are terminal. Plectranthus cylindraceus characterized by the dense verticals of flowers on the inflorescence axis, but the others have lax verticals. Presence of the hairs inside calyx tube distinguish P. tenuiflorus, whereas, lanceolate leaves and purplish calyx and corolla separate P. barbatus from P. lanuginosus which is leaves are ovate, calyx violet and bluish violate corolla. The anatomical study of the stems, leaves and petioles of investigated species shows good anatomical occurrence of characters that can be used in the separation of studied species. into two groups: the first group consists of P. arabicus, P. asirensis, P. lanuginosus and P. tenuiflorus, which can be distinguish by the dorsiventral leaves. Both of P. asirensis and P. tenuiflorus are characterized by three vascular boundless in leaves midrib which arranged in deep reniform vascular system at the P. asirensis, whereas shallow reniform vascular system observed in the P. tenuiflorus. The two other species: P. arabicus and P. lanuginosus are characterized by one vascular bundle in their midrib. Plectranthus lanuginosus can be distinguish by small vascular boundless arranged in stem sections and the obscene of the pericycle fiber boundless, but P. arabicus has four large vascular boundless in the stem with some small boundless and the occurrence of the pericycle fiber boundless . The second group consist of P. barbatus, P. cylindraceus and P. pseudomarrubioides which their leaves are isobilateral. Plectranthus barbatus can be distinguish by the cub-shaped petioles; whereas, the two other species have an elongated cub-shaped petioles. Shallow reniform vascular system in the petiole distinguish P. pseudomarrubioides, while deep reniform vascular system observed in the P. cylindraceus. The study of the trichomes on the leaves by SEM shows the importance of their types in the describing examined species. Glandular and a glandular hairs are the two observe hairs, which are different in their size and dens on both leave sides. Chemotaxonomical study shows some taxonomical evidences, which can be used for separation studied species. Routine were observed in all examined species except P. cylindraceus. Occurrence of the glycoside and aglycon compounds in the leaves of Plectranthus species, help to divided the species in three groups: the first consists of P. arabicus, P. barbatus, P. lanuginosus and P. pseudomarrubioides which are contains glycoside components, the second includes P. asirensis and P. tenuiflorus which are characterized by the occurrence of the both glycoside and aglycon, whereas the third group can be distinguish by the Kaempferol, Quercetin and Apigenin as aglycon components. Two keys are drown, one based on the morphological characters, the second on the anatomical characters of the stems, leaves and petiole |
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Supervisor |
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Dr. Farag Abdullah Al-Ghamdi |
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Thesis Type |
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Master Thesis |
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Publishing Year |
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1428 AH
2007 AD |
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Added Date |
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Tuesday, June 10, 2008 |
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Researchers
| حميد علي الصمداني | Alsamadani, Hameed Ali | Researcher | Master | |
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Files
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24219.pdf
| pdf | المستخلص |
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24220.pdf
| pdf | Abstract |
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