Vol. 73, No. 4: 315-325, 2004 ACTA SOCIETATIS BOTANICORUM POLONIAE 315 POLLEN MORPHOLOGY OF PLANTAGO SPECIES NATIVE TO POLAND AND THEIR TAXONOMIC IMPLICATIONS MA£GORZATA KLIMKO1, KRYSTYNA IDZIKOWSKA2, MARIOLA TRUCHAN3, ANNA KREFT3 1 Department of Botany, Agricultural University Wojska Polskiego 71C, 60-625 Poznañ, Poland e-mail: [email protected] 2 Laboratory of Electron Microscopy, Adam Mickiewicz University Grunwaldzka 6, 70-780 Poznañ, Poland 3 Department of Botany and Genetics, Institute of Biology and Environmental Protection, Pomeranian Pedagogical University Arciszewskiego 22B, 76-200 S³upsk, Poland (Received: March 29, 2004. Accepted: May 21, 2004) ABSTRACT Pollen grains of 9 species of the genus Plantago (Plantaginaceae), including 8 taxa native to Poland, were ob- served under a light microscope and a scanning electron microscope. Descriptions of grain sculpture are illustra- ted only SEM micrographs. The studied pollen grains were medium-sized or small, spherical or prolate spheroi- dal. Their sculpture was always verrucate with granulation. In the studied taxa, internal apertures had the form of pores. Their number ranged from (4)5-9(14). The pores were scattered on the surface of pollen grains. Identifica- tion features of individual taxa include: presence or absence of an annulus around each pore, annulus structure, ornamentation of the pollen grain and operculum, type of aperture membrane, number of internal pores, and pore diameter. We suggest that two new pollen grain types, characteristic of P. intermedia and P. arenaria, should be distinguished, and that P. alpina should be assigned to the P. coronopus type. KEY WORDS: Plantaginaceae, Plantago, pollen morphology, SEM. INTRODUCTION the sporophyte, whereas pollen size is determined both by sporophytic and gametophytic genotypes (Bedinger 1992; Pollen grains of the genus Plantago (Plantaginaceae) ha- McCormic 1993; Nepi et al. 1995; Ottaviano and Mulcahy ve been subject to scientific research for many years, main- 1989; Stanley and Linskens 1975; and references therein). ly in the field of paleobotany, because species like P. ma- It is unknown how the specific pollen wall patterns are de- jor, P. media and P. lanceolata are regarded as indicators termined, but the sculpturing is exclusively under sporo- of human settlements in prehistoric investigations. phytic control and no segregation of the exine pattern is Generative parts of plants, mature pollen grains in parti- known (Heslop-Harrison 1971, 1972). cular, are much less variable than vegetative parts. Hence, As a result of palynological studies, pollen grains of the pollen is a convenient material for investigation, because it genus Plantago have been divided into several types. Iver- is in a steady physiological stage, has a single set of chro- sen (1941) distinguished two types: lanceolata and major- mosomes, and forms large populations. Mature pollen gra- media. Müller (1943) added a third type, coronopus, and in size, exine sculpturing, and number of pores are the Casper (1975) another one, maritima. Taxonomic reviews most distinctive features (Erdtman 1952; Fægri and Iver- of pollen morphology based on modern materials distingu- sen 1992; Klimko et al. 2000). The ontogenesis of pollen ish pollen grain types characteristic of individual taxa or involves important genetic control phenomena, such as the else group several species in one type (Casper 1975; Clar- connection between meiocytes, callose synthesis for the se- ke, Jones 1977). However, the materials came mainly from paration of microspores, tapetal secretion, which is deposi- NW Europe. In Poland such investigations have not been ted as components of pollen coat, and finally the determi- conducted so far. Despite intensive research, there are still nation of exine patterns. The exine pattern is controlled by some discrepancies in classification, morphological de- 316 POLLEN MORPHOLOGY OF PLANTAGO SPECIES Klimko M. et al. scriptions of annuli of pores, ornamentation of pollen gra- 3. Wielkopolska, Nowy Tomyl Commune paths ins, shape and size of verrucae, type of granulation, pore 4. Wielkopolska, Mosina Commune near buildings diameter, and ornamentation of the membrane closing the 5. Wielkopolska, Puszczykowo Commune near buil- pores. Most papers present results of observations made dings under a light microscope (Straka in Casper 1975; Fægry, P. intermedia Gilib. Iversen 1975; Moore et al. 1991; Sadowska et al. 1986; 6. Pomerania, Rowy, Ustka Commune edges of lakes Stachurska et al. 1981) and only few under a scanning elec- 7. Pomerania, Karlino Commune cultivated fields tron microscope (Clarke, Jones 1977). Hence the aim of 8. Pomerania, Parsêcko, Szczecinek Commune culti- our study was to assess the variation of qualitative and qu- vated fields antitative traits of pollen grains in population material and 9. Wielkopolska, Stêszew Commune edges of lakes to perform a statistical analysis of similarity between the 10. Wielkopolska, Niwka, Puszczykowo Commune edges distinguished types of pollen grains, corresponding to stric- of ponds tly defined species. P. media L. The Polish flora includes ten Plantago species, including 11. Pomerania, Tczew Commune slopes of a pond three threatened taxa (Polish Red Data Book of plants 12. Pomerania, Pyrzyce Commune meadow 2001). P. coronopus L. is critically endangered in Poland, 13. Wielkopolska, Puszczykowo Commune roadside as it has been found in only one natural locality: Karsibór ditch in the SE part of Usedom Island (Piotrowska 2001). P. ma- 14. Wielkopolska, Skorzêcin, Witkowo Commune me- ritima L. subsp. maritima is also endangered (Piotrowska adow 2001), while P. atrata Hoppe subsp. carpatica (Soó) Soó 15. Wielkopolska, Konin Commune roadside ditch (= var. carpathica Pilger) is endemic to the Carpathians 16. Mazovia, Warszawa Commune slopes of a pond (Piêko-Mirkowa 2001). We have not managed to acquire P. coronopus L. subsp. coronopus material of P. winteri (Tacik 1967; Rutkowski 1998). 17. Pomerania, SE of Usedom Island, Karsibór, Brzeno Commune halophilic meadow P. maritima L. subsp. maritima MATERIAL AND METHODS 18. Pomerania, W³adys³awowo Commune halophilic The population material for pollen analysis was collected meadow from many man-made habitats. Only pollen of P. atrata P. atrata Hoppe subsp. carpatica (Soó) Soó subsp. carpatica originated from herbarium materials of 19. Ma³opolska, Zakopane Commune - Experimental POZB and the Experimental Garden of the Polish Acade- Garden, fresh and herbarium material (POZB) from Szalo- my of Sciences, while P. maritima subsp. maritima and P. ny Wierch coronopus subsp. coronopus from natural habitats. Pollen P. lanceolata L. grains were extracted from ripe anthers. 20. Pomerania, Przechlewo Commune meadow List of localities (Fig. 1): 21. Pomerania, Kluki, Smo³dzino Commune meadow P. major L. 22. Wielkopolska, Mosina Commune roadside 1. Pomerania, S³upsk Commune roadsides 23. Wielkopolska, Nowy Tomyl Commune roadside 2. Wielkopolska, Poznañ Commune roadsides 24. Wielkopolska, Poznañ Commune roadside 6 21 18 1 11 17 7 8 20 12 29 14, 27 3, 23 9 2, 24 10 5, 13 15 25 4, 22 16 2826 19 Fig. 1. List of localities. Vol. 73, No. 4: 315-325, 2004 ACTA SOCIETATIS BOTANICORUM POLONIAE 317 P. arenaria Waldst. & Kit. 29. Wielkopolska, Obrzycko Commune sandy patch 25. Wielkopolska, Puszczykówko, Puszczykowo Com- surrounded by forest mune sandy patch surrounded by forest Additionally, we analysed a sample of pollen of P. alpi- 26. Wielkopolska, Rogalinek, Mosina Commune sandy na L. for comparison with P. maritima, because of its ear- patch surrounded by forest lier classification (Clarke, Jones 1977). 27. Wielkopolska, Skorzêcin, Witkowo Commune san- Pollen grain dimensions were measured in the equatorial dy patch surrounded by forest (E) and polar (P) plane by means of Lucia 3.5 software 28. Wielkopolska, Szreniawa, Komorniki Commune (Laboratory Imaging Ltd., Czech Republic) on a computer sandy patch surrounded by forest linked with a microscope. The measurements were taken 2 3 24.774 µm 24.514 µm 10 µm 4 5 10 µm 3 µm 6 Figs 2-6. Plantago major L. Fig. 2. Pollen grains (×600). Fig. 3. Overall view with pores (×3100). Fig. 4. Overall view with verrucae (×3100). Fig. 5. Pore and granulate operculum (×6200). 30 µm Fig. 6. Verrucae (×6200). 318 POLLEN MORPHOLOGY OF PLANTAGO SPECIES Klimko M. et al. for 30 pollen grains from each locality of each species. lar, stronglysunken, diameter 4.59 µm (2.31-5.42 µm), A total of 900 pollen grains were measured. We calculated margin ill-defined, irregular, annulus absent; aperture mean values. On the basis of the results, the studied sam- membrane covered with granules forming an ill-defined ples were assigned to microspore size classes. The ratio of operculum. Endoaperture pore congruent with ectoaper- length in the P plane to that in the E plane enabled an as- ture, formed by a thin area of nexine. sessment of microspore shape, which was classified accor- Ornamentation: Verrucate, the verrucae well-defined, me- ding to Erdtman (1952). We also measured pore diameter dium-sized, slightly convex, irregular in outline. Their size and annulus width. Moreover, qualitative traits concerning varies around the pore. Channels between verrucae with di- the stage of development of the annulus, operculum, aper- stinct granules. ture membrane, and verruca structure, were taken into ac- Comments: Fægri, Iversen (1992) reported that the pores count. Values of those traits are given below: are ill-defined, without