Micromorphological studies of Carex section mitratae (Cyperaceae) in Turkey

RHODORA, Vol. 99, No. 900, pp. 368-375, 1997 MICROMORPHOLOGICAL STUDIES OF CAREX SECTION MITRATAE (CYPERACEAE) IN TURKEY Arzu Olgun and Osman Beyazoglu Karadeniz Technical University, Faculty of Art and Science. Department ot Biology, 61080, Trabzon, Turkey abstract . Scanning electron microscopy was used to examine achene epidermal features in species ot Carex section Mitratae and the allied section Acrocystis found in Turkey. Members ot section Mitratae share a particular achene phenotype. Micromorphological characters appear to be conservative, and show little variation between species of section Mitratae. Comparative data ot achene micromorphology support the placement of C. tomentosa with¬ in section Acrocystis. m Key Words: Carex, Mitratae, Cyperaceae, systematics. achene, SEM Carex sec tion Mitratae Kiik. has comprised three taxa in Tur¬ key: C. umbrosa subsp. haetiana, C. caryophyllea, and C. depressa subsp. transsilvanica. One species was recognized within section Acrocystis Dumort. [= Montanae (Fries) Carey]: C. to¬ mentosa (Nilsson 1985). These sections ( Mitratae and Acrocystis) m' have been combined into one unit, as section Onkerma (Rafin) Krecz. (Kreczetovicz 1935). Chater (1980) and Nilsson (1985) outlined several morphological features that distinguish the spe¬ cies of section Mitratae . Members of Carex section Mitratae are distinguished from taxa in other sections of Carex by achenes with annular, whitish apical discs. Achene epidermis characters have been used in many studies on Cat ex taxonomy at both the specific and the sectional levels (Grins and Ball 1988; Menapace and Wujek 1985. 1987; Menapace et al. 1986; Rettig 1986, 1990; Salo et al. 1994; Standley 1985, 1987a, b, 1990; Tallent and Wujek 1983; Toivonen and Timonen 1976; Waterway 1990; Wujek and Menapace 1986). Usually these characters have provided criteria useful for delim¬ itation of taxa at various levels. They have also been used for distinguishing species within critical groups (Rettig 1990; Stan¬ dley 1987a, b). However, studies on taxa within the C. crinita complex (Bruederle et al. 1989) and the C. fiava complex (Salo et al. 1994) indicated that achene micromorphology was not use¬ ful in distinguishing taxa because of the considerable amount of 368 1997] Olgun and Beyazoglu— Carex section Mitratae 369 Table 1. Collection data for Carex species used for SEM observations. Section Mitratae C. umbrosa Host, subsp. huetiana Boiss. Rize: Ka^kar, Olgun 58: Cimil, Olgun 63: trabzon: Solma y.. Olgun 83: £akilgol, Olgun 85. C. caryophyllea Latourr. Rize : Ballikoy, Olgun 15: Ovit, Olgun 57: Cimil. Olgun 64. C. depressa Link, subsp. transsilvanica Schur. trabzon: Siimela, Olgun 2; KTU Kampiis, Olgun 11: rize: Ballikoy, Olgun 16: Cimil, Olgun 74. Section Acrocystis C. tomentosa L. trabzon: Zingana, Olgun 9; Kiremithaneler, Olgun 13: Erikbeli. Olgun 76. variation within species. Studies on the sections Heleonustes (Toivonen and Timonen 1976), Folliculatae (Wujek and Menapace 1986) and Lupulinae (Menapace et al. 1986) illustrated that achene micromorphology may differ more drastically from one section to another than from species to species. In other studies, variation within well-defined sections was found to be as great as variation between sections (Menapace and Wujek 1985; Rettig 1986; Waterway 1990). Salo et al. (1994) indicated that the utility of achene epidermis characters as a basis of taxonomic decisions varies greatly in the different sections of Carex. In the present work, achene micromorphology of section Mi¬ tratae was examined by SEM and related section Acrocystis) was used for comparison. MATERIALS AND METHODS Perigynia containing mature achenes of all species ot Carex sections Mitratae and Acrocystis were taken from herbarium specimens deposited at the Karadeniz Technical University Her¬ barium (ktub). Three or four accessions of each species were examined. Observations were made on six to eight achenes from each accession. Collection data tor SEM studies are given in Ta¬ ble 1. Achenes were treated with a 1 : 9 (v/v) mixture of concentrated sulfuric acid: acetic anhydride and sonicated in ultrasonic cleaner for 1 to 2 hours to remove the outer cell walls (Tallent and Wujek 1983; Toivonen and Timonen 1976). Dried achenes were sputter 370 Rhodora [Vol. 99 coated with 200-300 A of gold before observation with a JSM6400 SEM. Upper shoulders of achenes were photographed at an accelerating voltage of 5 kV. Micrographs were usually obtained at magnifications of 1500X. Terminology used in describing the anticlinal walls and the silica deposits follows Rettig (1990). RESULTS AND DISCUSSION Representative scanning electron micrographs of four taxa are shown in Figures 1 through 6. As can be seen from the figures, the species of section Mitratcie share a particular achene micromorphology. Carex umbrosa subsp. huetiana, C. caryophyIlea, and C. depressa subsp. transsilvanica have convex silicon plat¬ forms with round comers and