View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Federal University of Agriculture, Abeokuta: FUNAAB Journal ISSN: Journal of Natural Print - 2277 - 0593 Sciences, Engineering Online - 2315 - 7461 and Technology © FUNAAB 2011 POLLEN STUDIES ON FOUR SPECIES OF CRASSO- CEPHALUM (MOENCH.) S. MOORE (ASTERACEAE) IN SOUTHWESTERN NIGERIA *A.S. OYELAKIN AND M.S. AYODELE Department of Biological Sciences, Federal University of Agriculture, Abeokuta, P.M.B. 2240, Abeokuta, Ogun State, Nigeria. *Corresponding author: [email protected] Tel: +2348035216157 ABSTRACT Twenty-three accessions of four species of the genus Crassocephalum were investigated on their pollen size, pollen morphological structure and fertility. Pollen sizes were obtained from polar and equatorial diameter measurements. Pollen fertility was accessed through the staining property in cot- ton blue in lactophenol reagent. The structural form of pollen grains was examined by means of a light microscope (X100 magnification). There was no significant difference in pollen size, structure and fertility among species investigated. C. crepidioides had relatively the largest size of pollen grains (28.10±1.67 µm) (media), while C. rubens pollen were relatively most fertile (98.7%). However, pollen grains of the species were tricolporate with three germ pores except in C. crepidioides which had up to six germ pores (multiporate). All pollens in the species were fenestrate type with high fertility. The study suggests that number of germ pores in addition to pollen morphology be used in species separa- tion. Key words: Crassocephalum, pollen grains, Pollen morphological structure and fertility INTRODUCTION (Tindall, 1983). A decoction of the leaves of The genus Crassocephalum (Moench.) S. Crassocephalum species is used as lotion for Moore comprised of green leafy vegetables headache and as a mild stomachic. Leaf ex- popular and widespread in many tropical tract of C. crepidioides showed moderate an- and subtropical regions but more promi- timutagenic activity in Salmonella typhinurium nent in Tropical Africa (Fowomola and Ak- and produces dihydroisocoumarins that has indahunsi, 2005). Crassocephalum species shown antimalarial activities against Plasmo- constitute special delicacies in Southwestern dium falciparum (Schippers, 2000). Nigeria and feature prominently among nu- merous edible plants common to the Several studies and reviews have been carried Yoruba culture (Bankole et al., 2003). The out on the size, structure, and fertility of pol- edible fleshy mucilaginous leaves and stems len grains of species in the family Asteraceae are eaten as vegetable and as medicine for (Jones, 1979; Hodalova and Martonfi, 1995; several different ailments (Grubben and Ayodele, 1999; Otieno and Mesfin 1984; Denton, 2004; Fowomola and Akindahunsi, Nair and Lawrence, 1985; Moore and Webb, 2005). The leaf sap of C. crepidioides is used 1978). The usefulness of pollen size, shape, to treat stomach upset and fresh wounds and structure as specific characteristics in the J. Nat. Sci. Engr. Tech. 2011, 10(2): 44-51 44 *A.S. OYELAKIN AND M.S. AYODELE family Asteraceae has been the subject of in southwestern Nigeria (Table 1) between these several studies. Clausen (1962) citing January 2006 and December 2007. 23 acces- Eneroth (1951) demonstrated that it is pos- sions collected from different populations sible to distinguish species in the family As- were labelled with different accession num- teraceae on the basis of pollen size in spite bers. Specimen from these populations had of some overlap of the species in this re- their identities confirmed using Herbarium spect. Similarly, Oschurkova (1959) who specimens at the Forestry Research Institute studied 16 Russian species reported that of Nigeria (FRIN) and Obafemi Awolowo many of them could be separated by the University Ile-Ife, Nigeria. Ten to twenty same criterion. Leopold (1956) reported achenes of each accession were planted in that it was difficult to distinguish the 9 birch sterilized loamy soil contained in 10-litre species native of New England on pollen plastic buckets-five buckets per accession. size alone, but concluded that differences in They were arranged 1m apart in four rows at pollen diameter could also be used to sepa- the Department of Biological Sciences ex- rate the shrubby birch species. Kapp (1969) perimental garden, University of Agriculture, warned that size alone could not be used as Abeokuta, Ogun State, Nigeria. The germi- a parameter to separate pollen grains. Jones nated seedlings were nurtured till flowering. (1981) suggested that other pollen charac- Slides for pollen studies were prepared by ters in addition to pollen size be used in dusting pollen grains from the opened flow- species separation. Scientific reports on the ers in a drop of cotton blue in Lactophenol pollen grains of the Nigerian species of the on a clean glass slide and covered with a Crassocephalum are not available. The pollen cover slip. Five slides from five different size, structure and fertility in the genus Cras- flowers collected from different plants of the socephalum therefore, require some attention. same accession were prepared for each ac- cession. Pollen fertility was estimated by The objective of this study is to provide counting pollen grains from ten fields on detailed description of the pollen grains of each of the five slides prepared for each spe- some four Nigerian species of Crassocepha- cies at X100 magnification. Pollen grains lum with reference to their pollen size, with cytoplasmic content stained deep blue structure and fertility. The data obtained were considered fertile while those that were would be used to draw conclusions on the not stained or only partially stained or with pollen of the Crassocephalum rubens collapsed outline were considered sterile. (Juss.ex.Jacq) S. Moore, C. crepidioides (Benth.) S. Moore, C. biafrae (Oliv. & Hiern) S. Moore and C. togoense C.D. Adams. MATERIALS AND METHODS Achenes were collected from field popula- tions of Crassocephalum during series of field trips covering different ecological locations J. Nat. Sci. Engr. Tech. 2011, 10(2): 44-51 45 POLLEN STUDIES ON FOUR SPECIES OF CRASSOCEPHALUM …. Table 1: Location & collection data of field populations of C. crepidioides, C. rubens, C. biafrae & C. togoense Name & accession number of Location of collection Description of location species C. crepidioides (Benth.) S. Routes: Osiele village, along Guinea & Derived savannah in Moore AS/010,012,015,018,& Ibadan-Abeokuta road, No. 21, yam/Maize farmland, vegetable 022 Gbada Salami Street, Idimu Lagos, garden, waste place, roadside Adodo village, Igbeti/Ogbomoso, Aguo village Ibadan-Oyo road, University of Ado-Ekiti campus. C. rubens (Juss. Ex Jacq.) S. Routes: Guguru village along Ig- Derived & Guinea savannah in Moore (purple floret) AS/001, beti/Ogbomoso Adodo village, yam/maize farm, road side, yam/ 004, 005, 009, 014, & 017 near Ogbomoso, Obantoko/ pepper farmland, cleared land Adatan,Asero, Abeokuta, Okuku, along Ikirun/Ilorin road. Guguru village, near Ogbomoso/Igbeti, roadside, besides local government secretariat, Epe. C. rubens (Juss. Ex Jacq.) S. Routes: Telemu village along Iwo- Guinea & Derived savannah in Moore (light purple floret) Osogbo road, Gurugu village, yam farmland, waste place by the AS/002, 003, 006, 007 & 016 along Ogbomoso/Igbeti, Aramoko roadside, abandoned plot of land, -Ado-Ekiti road. Joju village, uncultivated burnt forest Sango-Otta C. rubens (Juss. Ex. Jacq.) S. Routes: Igbeti township, Oru/ Guinea & Derived savannah in Moore (white floret) AS/013, Ijebu Igbo road. Ibadan/ Yam farmland ,waste place road- 019 & 020 Abeokuta; Bakatari Township side in dilapidated building C. biafrae (Olive. Hiern) Routes: Fiditi along Oyo-Ibadan Derived Savannah with loamy soil; S. Moore AS/008 & 011 road. , Moniya Cocoa plantation. C. togoense C.D. Adams Routes: Apomu Ikire; Eleekara, via Derived Savannah with sandy AS/021 & 023 Idi-Igba, Ilora, Ibadan -Oyo road. loamy soil; abandoned farmland and weedy roadsides. J. Nat. Sci. Engr. Tech. 2011, 10(2): 44-51 46 *A.S. OYELAKIN AND M.S. AYODELE Pollen fertility percentages for each species RESULTS AND DISCUSSION were calculated by expressing the number Little or no variations in size were observed of fertile pollen grains as a percentage of in the pollen grains of four species investi- the total pollen grains counted. gated (Table 2). i.e. % pollen fertility = Stained pollens X 100 Photomicrographs of pollen grains for the Total pollens counted species studied were recorded (Fig. 1). All Pollen size was determined by measuring the species have fenestrate pollen grains as the polar and equatorial diameter of fifty described by Moore and Webb (1978). These full and deeply stained randomly selected were single grains with a coarse network of pollen grains from ten field of view on the high echinate ridges (pointed projecting five slides prepared for each accession at spinous elements) separated by large spaces X400 magnification using ocular microme- (lacunae) in a fixed geometrical pattern. This ter and variations were noted (Brookes and type of pollen grains is characteristic of the Thomas, 1967). The ocular measurements family Asteraceae (Moore and Webb, 1978). were later converted to microns using stage The species studied have asteroid fundamen- micrometer. Mean and standard deviations tal pattern with caveate exine carrying spines were calculated for the measurements. Sta- with a