ACTA AGROBOTANICA Vol. 61 (2): 35–47 2008 ECOLOGICAL FEATURES OF AMBROSIA ARTEMISIIFOLIA L. FLOWERS AND CHARACTERISTICS OF AMBROSIA L. POLLEN SEASONS IN THE CONDITION OF LUBLIN (POLAND) IN THE YEARS 2001-2008 Elżbieta Weryszko-Chmielewska, Krystyna Piotrowska Department of Botany, University of Life Sciences, Akademicka 15, 20-095 Lublin, Poland e-mail: [email protected] Received: 19.09.2008 Summary brosia is recorded in different regions of the country: In the study, the biology of fl owering of Ambrosia ar- Ambrosia artemisiifolia L., A. psilostachya DC. and temisiifolia L. was investigated and the pattern of the Ambrosia A. trifi da L. (Tacik, 1971; Rutkowski, 1998; pollen seasons in Lublin in the years 2001-2008 was character- Zają c and Z a j ą c , 2001). A. artemisiifolia has been ised. The structure of male and female A. artemisiifolia fl owers noted, inter alia, in the Lublin region (Fijał kowski was observed in cultivated plants under controlled conditions 1994), in Wrocław (Malkiewicz and W ą sowicz, in the 2000 vegetative season. The number of pollen grains 2003), in the Upper Silesia region (C h ł opek and produced by the stamen, fl ower, infl orescence and plant was Tokarska-Guzik, 2006). Ambrosia psilostachya determined. It was shown that in A. artemisiifolia fl owers non- sites have been described, among others, in Szczecin functional pistils occurred with a reduced ovary, performing the (Ć wikliń ski, 1968; Puc, 2004) and the Lublin role of a pollen presenter. The pistils found in female fl owers region (Ś wię s and Wrzesień , 2002). differed signifi cantly in their morphological features from the Plants of the genus Ambrosia brought to Poland pistils in male fl owers. It was calculated that one stamrn pro- duced an average of 3 375 pollen grains, whereas one fl ower are most frequently encountered near railway tracks 16 875. A plant which produces 20 racemes may release over or at ruderal sites. They also grow on dry swards and 420 million pollen grains into the atmosphere. at roadsides, and they sometimes occur as weeds in The Ambrosia pollen seasons in particular years had dif- crops. In some locations, they are treated as species oc- ferent patterns. In some years, the days of maximum concentra- curring temporarily (Fijał kowski, 1994; Ś wię s tion were in the second half of August, in other years in the and Wrzesień , 2002). They belong to quarantined fi rst half of September. Over the 8-year period, the maximum plants. 3 daily concentration had a mean value of 116 pollen grains in m Ambrosia pollen grains are the most frequent (31-311). Annual total concentrations of Ambrosia pollen grains cause of pollen allergy in North America (Bousquet ranged between 194 and 1200 grains, and it was 523 grains on the average. The pollen seasons were characterised by the oc- et al. 2001). C omtois (1998) defi nes representatives currence of several-day-long interruptions in the presence of of the genus Ambrosia as allergophytes. airborne pollen in the atmosphere of Lublin, which may indicate In A. artemisiifolia pollen grains, one of aller- the long-distance transport of Ambrosia pollen. gens with the strongest effect on humans (Amb a 1) is found, which causes allergies in many countries in an Key words: Ambrosia artemisiifolia, fl oral morphology, pollen ever increasing number of people (C omtois, 1998; presenter, amount of pollen grains, pollen seasons, Jäger, 2000). annual total concentrations In Warsaw the frequency of positive skin tests to the ragweed pollen allergen is found to have in- creased in patients from 0.3 % in 1998 to 1.5 % in 2003 INTRODUCTION (Rapiejko, 2004). Ambrosia artemisiifolia L. (Asteraceae) comes Ambrosia pollen has been found in the air of from North America. It was transferred to Europe, in- different Poland’s cities for many years (K asprzyk, cluding Poland, together with a shipment of cereals at 1996, 2008; Stach and Silny, 1999; S t ę palska the end of 19th century (Holzfuss, 1937). In Poland et al. 2002; M alkiewicz and W ą sowicz, 2003; the occurrence of several species of the genus Am- Weryszko-Chmielewska et. al. 2003; Puc, 36 Elżbieta Weryszko-Chmielewska, Krystyna Piotrowska 2004, 2006; Piotrowska and Weryszko- The fi rst male fl owers develop in the circum- Chmielewska, 2006). ference of the anthodium. The fl ower height reaches The aim of the study was to investigate the biol- 1.7 mm, on the average, and its diameter 0.6 mm. The ogy of fl owering of A. artemisiifolia growing in ex- yellow-green semi-transparent corolla is composed of perimental plots in Lublin in order to determine the 5 fused petals which form in their upper part free lobes number of pollen grains produced by the stamen and opening only slightly at anthesis (Figs 2 A, B). Anthers the fl ower as well as to compare the pattern of Ambro- are the fi rst to come out through an opening formed at sia pollen seasons in the years 2001-2008. the apex of the corolla in some male fl owers. In other male fl owers, the apical portion of the non-functional MATERIALS AND METHODS pistil, which forms a brush-shaped pollen presenter, was observed to appear fi rst between the corolla lobes Ambrosia artemisiifolia L. seeds were obtained (Figs 2 E, F, G). The pistil with a reduced ovary has from the Botanical Garden in Dijon (France). Plants a cylinder-shaped style (Figs 2 H, 3 E). In its upper grew in experimental plots in Lublin under control- portion, the style is provided with brush-shaped out- led conditions during the 2000 growing season. Over growths which sweep out and raise pollen, released in a dozen plants were subjected to observations. the fl ower inwardly from the bursting anthers already Details of the structure of male and female fl ow- inside the closed corolla. This pistil in the bud reaches ers of the investigated Ambrosia artemisiifolia plants the half-height of the corolla (Fig. 2 C) and gradually and their development were observed. elongates as the fl ower develops (Fig. 2 D). The number of male fl owers in fl ower heads, The stamens (5) observed in the buds of male the number of fl ower heads borne on one stem and on fl owers were fused by their heads, but at anthesis the plant as well as the diameter of fl ower heads were they separated (Figs 3 A, B). The fi laments were very determined in ten plants. The number of pollen grains short in the bud (Fig. 3 F). There was an outgrowth produced in the stamen was evaluated as a mean from at the apex of the elongated anther (Figs 3 B, F). At 10 anthers from which separate smear slides stained anthesis, the anthers stuck out much above the corolla with basic fuchsine were made. The number of pollen (Fig. 3 A). grains produced by a single fl ower, fl ower head and Female fl owers are gathered in single-fl owered plant was determined. anthodia subtended by small bracts. These anthodia The investigations of pollen concentrations grow in clusters beneath the male infl orescences (Figs were carried out by the volumetric method using 4 A, C). They are subtended by several hairy bracts. a VPPS 2000 Lanzoni pollen trap. The sampler was The female fl ower is composed of one pistil with an placed in Lublin’s city centre (Śródmieście) at a height inferior ovary and two fi liform red-coloured stigmas of 18 m. Daily Ambrosia pollen concentrations and an- (Fig. 4 B) which elongate signifi cantly during fl ower- nual total concentrations over the 8-year study period, ing (Fig. 4 C). In the upper portion of the receptacle 2001-2008, were calculated from the obtained aerial fused with the ovary, the calyx is visible, forming a ring plankton samples. of tiny nodules which remain later on the fruit. In the basal part, the pistil’s stigmas are enclosed by strong- ly reduced, hairy petals of the corolla (Fig. 4 B). The RESULTS share of female fl ower heads in the total number of Floral morphology infl orescences in the investigated plants was small. Ambrosia artemisiifolia is a herbaceous plant. It was found that one stamen produced 3 375 In the conditions of Lublin, in 2000 the plants reached pollen grains, on the average (Tab. 1). The calculations a height of 100 cm. They fl owered from 20 August till show that one fl ower produces an average of 16 875 the end of October, producing on their stems numerous grains, one fl ower head 421 875 grains, whereas a ra- anemophilous fl owers occurring in tiny fl ower heads ceme 21 093 750 pollen grains. A plant which produc- (Figs 1 A, B). es 20 racemes releases on the average over 420 mil- Flowers of this species are unisexual. The down- lion pollen grains into the atmosphere. These grains ward pointed fl ower heads (anthodia), with an aver- are tricolporate. They reach an average size of 18 x 20 age of 25 staminate fl owers clustered in them (Tab. 1, μm. The exine surface is covered with spinules with Figs 1 C, E, F), are 4.0 – 6.5 mm in diameter. They a length of about 1 μm (Figs 3 G,H). are grouped in loose, terminal racemes composed of 50 fl ower heads, on the average (Tab. 1). The antho- Pollen seasons dium is protected by a cup-shaped involucre, made up The start of the Ambrosia pollen season was of several fused bracts, which has a toothed edge or is noted in Lublin in the study years (2001-2008) be- provided with upward bent fl aps (Fig.