Vol.7l. No.2: 163-170.2002 ACTA SOCIETATISBOTANICORUM POLONIAE 163

POLLINATION BIOLOGY OF HERACLEUMSPHONDYLIUM L. (). THE ADVANTAGES OF BEING WHITE AND COMPACT

MeRcnI ZYCH WarsawUniversity Botanic Garden Aleje Ujazdowskie4,00-478 Warszawa, Poland e-mail:[email protected]. pl (Received:August l,zmL. Accepted:February Il,2OO2)

ABSTRACT Two questions were addressedin the present study: ( I ) What are the main of the two subspeciesof H. sphondylium?, and (2) Do the studied sharethe pollinators' set or are they attractive for different groups of ?The survey showed that among 40 taxa visiting both subspeciesof H. sphondylium approx. only 53Vo caried significant pollen loads. However, the Importance Coefficient (IC) calculated for each insect group, and based on observation of insects' abundance,within- activity and pollen load revealed that only two taxa in case of H. s. ssp.sibiicum (Thicops nigifrons, Eiozona syrphoides) and four in case of H. s. ssp.sphondylium (T. nigifrons, E. syrphoides,Meliscaeva cinctella and ustulata) were truly important polli- nators. Although both subspecieswere visited by similar insects, H. s. ssp. sphondylium, with its characteristic compact and white , was visited more frequently by Diptera and , while yellow-greenish loose umbels of H. s. ssp,sibiricum were preferred by Coleoptera.This paper indicates that the concept of faithful pollinators may also apply to a broader spectrum of Apiaceae,usually consideredprimitive in terms of pollination strategies,and suggestspossible ways of differentiation in two closely related taxa.

KEY WORDS: sphondylium L., Diptera, colour morphs, pollination, pollinator importance.

INTRODUCTION tegazzianum(Grace and Nelson 1981) showed a considera- ble difference in pollinators' importance. Analysis of in- For the last decade the traditional view of pollina- sect visitors of two American umbelliferean genera Tha- tion systemshas been questionedwith arising evidencefor spium and Zizia showed that for most pollinations (up to widespread generalisation of plant pollination strategies 75Vo) orly few insect species were responsible (Lindsey and opinion that the previously accepted idea of a direct 1984). It is also noteworthy that in case of closely related link between the observed floral traits and pollinators mi- H. sphondylium and H. mantegazzianum,growing sympa- ght not be so simple (Waser et al. 1996; Johnson and Stei- trically in a mixed population and characterisedby similar ner 2000). As shown by different authors, plants conside- pollination systems,different pollinators' assemblageswe- red specialised may be pollinated by a considerablenum- re observed (Grace and Nelson 1981). It may have been ber of taxa (Beattie 1971), and primitive species,as those caused by the difference in heights of the inflorescence. 'faithful of Apiaceae, could have pollinators' (Bell 1971). A similar situation may probably be found in other closely The descriptions of flower visitors of Apiaceae list nu- related taxa. merous insectsbelonging from severalto a few hundred ta- Apart of inflorescenceheight, flower colour and symme- xa (Drabble and Drabble 1917, 1927; Corbet 1970; Bell try may be responsible for attracting different groups of 1971; Grace and Nelson 1981; Lindsey 1984; Sheppard pollinators (Faegri and van der Pijl 1979; Proctor, Yeo and 1991; Proctor, Yeo and Lack 1996; Dlussky 1998; Lam- Lack 1996). Usually this kind of studies are conducted on bom and Ollerton 2000), only for the dipteran family Ta- the level of genera, species or for artificial flowers (e.g. chinidae Karczewski (196'7) describes33 speciesobserved Lunau 1993; Johnson and Dafni 1998). There are very few on flowers of H. sphondylium. works that focus on the consequencesof intraspecific dif- More recent studies however reveal that flower visitors ferences on the successof individuals (Herrera 1996). are not synonymous with pollinators. For example pollen Such relationship was found for two colour morphs of loads and number of visits to different speciesof Angelica Raphanus raphanistrum (Brassicaceae).In a mixed white- (Bell and Lindsey 1978) and H. sphondylium and H. man' and yellow-flowered population, individuals with yellow POLLINATION OF HERACLEU M SPHONDYLIUM ZychM. flowers were found more attractive for butterfly and hover- Study site fly pollinators (Kay 1976). Also evidence for selection of The observations were conducted in two sites in the flower colour was presented in Delphinium nelsonii same forest complex in Wigry National Park (NE Poland), (Waser and Price 1983). Further analysis of closely related the distance between the two populations was approx. 3 taxa with different flower morphology could be useful for km. The population of 11.s. ssp. sphondylium was situated tracing the possible ways of evolution of features connect- near the village Krzywe in the forest clearance approx. 50 ed with sexual reproduction and subsequentlyto show the m from the road Suwalki-Sejny (road no. 660), and the existing trends of speciesdifferentiation (Herrera 1996). So population of H. s. ssp,sibiicum on the border of the for- far no evidence on this matter has been presented for est sections 133 and 134. Both grew in similar habitat con- Apiaceae. ditions, along the forest road in mixed spruce-pine forest, Among European species Heracleum sphondylium L. and consistedof similar number of individuals. (hogweed) may serve as possible object for similar studies. Two of its subspecies(f1. s. ssp. sphondylium and ly'. s. ssp. Field observations sibiicum), formerly considered separatespecies, differ in Field observationswere conductedon23-21 July of 1998. flower and inflorescence morphology. The former has a These four days representedthe peak of flowering for the white corolla with flowers with elongated petals arranged primary umbels, also the weather was good enough to make on the edge of an umbel, while the later has greenishpetals the observationspossible. Only primary umbels with at le- 'edge with no such effect' (Gawlowska 1961, Sheppard ast50Vo of flowers in the male phasewere chosenfor obse- 1991).It seemspossible that thesefloral characteristicsmay rvations. This restriction was implied by the fact that main- serye as attractants for different groups of pollinators which ly these umbels are responsiblefor seedproduction (Shep- would create a mechanism of differentiation between the pard 1991). The observation started at 8.30 a.m. (the first two related taxa. recording) and ended at 7.00 p.m. (the last capturing). The In the present study I was especially interested in time was chosen on the basis of earlier observationsrevea- answering the following questions: ling that before 8.00 a.m. and after 7.00 p.m. flowers of ho- (1) What are the main pollinators of the two subspecies gweed are visited by insectsonly occasionally. of H. sphondylium? Every day eleven rounds of observationswere conducted (2) Do the plants studied share the pollinators' set or are (except 24rh July - nine rounds, observations stopped by they rather attractive for different groups of insects? rain; and 25th- two rounds). Each round lasted t hour and comprised of three phases: random choice of an umbel, video recording, and insect capturing. MATERIAL AND METHODS Once selectedumbels were not excluded from the next round and therefore it was possible that the same umbel H eracl eum sphondylium L. was observedtwice or more times. H. sphondylium is a perennial (hemicryptophyte) (Rabot- After an umbel had been selected it was stick bound to nov 1956, Sheppard 1991), not a biennial as often stated prevent it from wind-causedmovements. Then for 10 min- (e.g. Brummitt 1968), with cauline leaves arrangedin a ro- utes insect activities were recorded using an 8 mm video sette producing erect flower stems up to 3 m tall. It is wi- camera (Sony TR-3200). The camera was set on a tripod at despread in forests and woodland clearings, riverbanks, a distance of about 0.5 m from the umbel. The recording and tall montane-herb grasslands(Sheppard 1991). In Po- field covered the total umbel surface. 20 minutes after land it is usually described as a common meadow species recording, for l0 minutes, all the insects visiting an umbel (Gawlowska i956), growing also in thickets, on roadsides were collcted either with enthomological net (Diptera, and forest fringes (Rutkowski 1998). Its geographicalran- Hymenoptera, Lepidoptera) or directly to plastic vials ge includes most of the European countries, except the (Coleoptera,Hemiptera). Insects were killed with ethyl extreme north, parts of the Mediteranean region and some acelate and stored dry for further investigations of their Atlantic and Mediterranean islands (Brummitt 1968; Shep- pollen loads. Aphids and other small, sap sucking insects pard 1991). (e.g. Thysanoptera)were excluded from the analysis. H. sphondylium rcproduces mainly by seeds;vegetative division of root stock, although occasionally occurring, is Pollen loads analysis not important (Sheppard 1991). The open, protoandrous For investigation of pollen loads carried by insects visit- flowers, arrangedin compound umbels, are antomophilous ing flowers of H. sphondylium amodified method of Grace with insects visiting flowers for pollen and excluded and Nelson (1981) and Lidsey (1984) was used.An insect by exposed swollen base of the style called stylopodium. was put on the microscopic slide and pollen from its body Most of the flowers are actinomorphic, however the outer was removed using a thin brush until no remaining pollen flowers in umbellets may be zygomorphic (Gawlowska was visible. This was done under stereoscopicmicroscope. 1956, 196I; Sheppard 1991). Umbels, depending on their The pollen was then stained with a drop of acetoorceine order, may comprise hermaphrodite or male flowers (i.e. and covered with microscopic cover glass. After that the flowers with aborted female parts). However, the percent- brush was carefully cleaned so the pollen could not conta- age of male flowers is not high and does not exceed4OVo in minate the next sample. Pollen samples were analysed tertiary umbels; in primary umbels hermaphrodite flowers using a light microscope.All H. sphondylit'uzpollen grains usually constitute IO}Vo (Wr6blewska 1992). Flower from randomly selected five areas on one sample were colour varies from greenish, greenish-yellow (11. .t. ssp. counted. Arithmetic mean of the counts, after extrapola- sibiicum), to white or pinkish (11.s. ssp. sphondylium). tion, was used to calculate the pollen load of a given indi- Vol. 71.No. 2:163-170.2002 ACTA SOCIETATISBOTANICORUM POLONIAE 165

vidual. ANOVA performed for the first 26 counts showed compound umbels, may in many Apiaceae act as reproduc- that the variance among fhe counts of a single sample was tive units (Bell 1971). The importance of the insect visitors significantly lower than variance among the samples to H. sphondylium was calculated using a pollinator impor- (F=2.073, P<0.01), this may account on the adequacyof tance measure(I): the method used. [Equation l] Measuing the pollinators impofiance L=VxUxPL Analysis of insect activities were based on video record- Where: ings. The number of visits and within-umbel activity (no. I* - importance of insect speciesX, of umbellets visited) of all insect visitors were measured. V - no. of recorded visits + no. of individuals of species This seems a reasonablemeasure becauseumbellets, with X captured/ total no. of visits recorded + total no. of indi- overlapping, elongated petals of the outer flowers, forming viduals captured,

Table L Number of insect visitsr on flowers of two subspeciesof H. sphondylium and the avera1epollen load carried by an individual. Video - no. of individual visits recorded; Capture - no. of individuals captured; PL - pollen load shown on the relative ss4le .**x > *x 2 * > t (trace)> - no pollen, x no data. hobability (P) of such distribution calculatedfrom cumulative binomial distribution.

H. sphondylium H. sphondylium ssp.sibiicum ssp.sphondylium

Video Capture PL Video Capture PL Diptera Cheilosia sp. I t ns 3 0 Chloropodidae 4 I 0.013 11 5 Epi syrphus balt eat us (Deg.) I ns J z t Eio zo na syrp h o i d es (F all. 1 2l 9 ns l0 Euit h ia co nsob ri na (Meig.) 0 z ns 2 Fannia sp. 0 0 ns 0 5 Fanniidae 0 1 <0.005 20 l0 I sc hy ro syrp h us g la uc ius (L.) 0 0 x ,ns 0 I Lut'illa c'aesar(L.) 3 ns 5 z M eI i sc aev a c incte I la (Znlt.) 27 t5 t <0.005 113 q M orellia aenest'ens (R.-D.) 0 z ns 1 I Myathropaflorea (L.) 0 2 ns 0 I P haonia angelicae (Scop.) 0 1 <0.05 I o P laty chira radi cum (Fa&.) 0 0 ns 0 1 Sepsidae 0 0 <0.005 t93 30 Syrphidae 0 0 ns I 0 Syrphusibesii (L.) 0 0 x NS 0 I Thrit'ops ni gifrozs (R.-D.) t27 45 NS 126 Vo luce I la pe Iluc e ns (L.) 0 2 NS 0 0 x Coleoptera Dasytes sp. 38 20 <0.005 9 9 t Meligethes sp. )+ t4 <).005 5 l5 Mordellistena sp. 3 J ns 0 I Rhagonychafulva (Scop.) 0 I ns I I St e n ureI I a mela nura (L.) 0 6 NS 1 2 Strangalia maculat a (Poda) 0 I NS 0 0 x Tichodes apiarus (L.) 0 1 ns 0 0 Hymenoptera Apoidea 0 0 x ns 2 0 x

Arge ustulata (L.) I 0 ns I J Bombus sp. 0 0 ns 0 Cimbex sp. 0 0 x ns 0 I Hymenoptera 0 0 x NS I 0 Ichneumonidae I ns 7 4 M acropisfulv ipes (Fabr.) 0 1 NS 0 0 Sphecidae I 0 ns 0 0 x Vespidae 0 0 ns I 0 x Hemiptera Calocois sp. J 5 <0.05 0 0 Lygus sp. 0 t2 t ns A 6 lrpidoptera Arast'hnia levana (L.) 0 0 ns 0 Argynnis paphia (L.) 0 2 ns 0 Pyralidae 0 0 ns I

I Eristalis arhustorum (L.), Eristalis pertinax (Scop.), Gymnosoma rotundata (L.), Tabanus bovinus (L.) (Diptera) and Zygaena jllipendulae (L.) (Lepidopeha) were seenduring preliminary observations,however non of thesewas noted during the study period POLLINATION OF HERAC LEU M SPH ONDY LII] M ZychM.

U - mean no. of umbellets visited by speciesX within an 7oo umbel / mean no. of umbellets in an averageumbel in the population surveyed, 600 I H s. ssD. sibiricum PL - average pollen load carried by an individual of E H s. ssp. sphodylium speciesX. 5oo This was then summarisedfor each subspeciesand treat_ 4oo ed as 1.0 to obtain the pollinator importancl coefficient for each insect taxon (IC). soo

Insect identification and statistics zoo Most of the insects were identified to the specieslevel. In many cases video recordings allowed to identify the species;when this was impossible I tried to identify insects to the lowest possible rank (usually family). DcHyHe All statistical calculations were perfonned either manual_ Fig. l. No. of individualsof differentorders visiting ly or using STATISTICA pL (StatSoft poland, flowers of Krak6w) two Heracleumsphondylium subspecies (video and capture, run on PC computer sum_ mariseddata). D - Diptera,C - Coleoptera,Hy _ Hymenoptera, He - Hemiptera,L - trpidopetra.

RESULTS The most frequent visitor of ^F/.s. ssp. sibiicum (video and capture) was Thicops nigifrons (R._D.) (Muscidae) _ During observationsof flowers of .F/.s.ssp. sibiicum and more than 34Vo visits. This fly was also encountered fre_ 1/.s. ssp. sphondylium 152 and 184 insects were captured, quently on flowers of F1.s. ssp.sphondytium (2OVovisits) respectively. During the analysis of video records 269 vis_ in which however the small Diptera of family Sepsidae its to flowers of H. s. ssp.sibiicum and 53g to flowers of were more frequent (almost 31Zo visits). These were not I/. s. ssp. sphondylium were observed. The summarised s€en on l/. s. ssp. sibiicum flowers. Although quite abun- number of visits shows that the latter plant was visited sig_ dant, Sepsidaewere unimportant pollinators because they nificantly more frequently (p<0.005, probability of suctr carried no pollen on their bodies. distribution based on cumulative binomial distribution). For both subspeciessurveyed the biggest pollen load has The list comprising 40 taxa belonging to five orders been found on the body of a single individuil of Strangalia (Hymenoptera, Lepidoptera, Diptera, Hemiptera and maculata (Poda) (Cerambycidae) captured on Ii. s. ssp. Coleoptera) is presented in Table l. Among them, 15 sibiicum. Among the most frequent visitors the biggeit species were only occasional (less visitors than 5 visits _ pollen loads were carried by individuals of Eiozoniiyr- video and capture). For both the subspecies,the highest nloidy (Fall.) (Syrphidae), Arge ustutata (L.) (), percentageof visits belonged to Diptera (64Vofor FI. s. ssp. Eurithia consobrina (Meig.) (Tachinidae), Morettia sibiicum, and 897o for ^F1.s. ssp.sphondytium). The leist aenescens(R.-D.) (Muscidae) andT. nigifrons (Muscidae) frequent visitors were Lepidoptera - only 2 visits on flow_ (Table 1). Beetles of genera Dasytes (Melyridae) and ers of H. s. ssp. sibincum and 3 on 11.s. ssp. sphondylium Meligethes (Nitidulidae) spent most of the time on hog_ (in both cases less than O.5Va of all visits). Also weed flowers, however their efficiency as pollinators was Hymenoptera were rare visitors - they accountedfor only relatively small. Individuals of Dasytes carried only trace 2Voof visits on 11. s. ssp.sibiicum flowers and 3Zo visits of pollen and visited on the average one umbellet in the on11.s. ssp.sphondylium(Fig. I). single umbel, similarly to Meligethes that carried almost no

Lygus

Calocoris

lchneumonidae

Cheilosia

E- balteatus

E. syrphoides

L. caesar

Apoidea

T. nigrifrcns

Bombus

0 1 2 3 4 5 6 7 I 9 10 no ot umbelletsvisited

Fig' 2' The average number of umbellets of H. sphondylium ssp. sphondylium and,H. sphondylium ssp. sibiicum visited by different insect taxa. Vol. 71,No. 2: 163-170,2002 ACTA SOCIETATISBOTANICORUM POLONIAE pollen. I observed similar long visits for carnivorous DISCUSSION Hemipteran genera Calocois an.dLygus. They also visited one umbellet on the average and carried only trace of It is generally agreed that the number of pollinators (or pollen - their pollination importance was therefore small. list of flower visitors) is a poor measureof flower speciali- Bumblebees (Bombus sp.) made the longest trips on an sation and pollinators' importance (Weiser et al. 1996; inflorescence,and visited almost 2/3 of umbellets in a sin- Johnsonand Steiner 2000). Many authors statethat the best gle umbel (Fig. 2). Unfortunately it was impossible to cal- description of pollinator importance can be achieved by culate IC for this taxon because no individual was cap- direct methods, such as measuring pollen loads deposited tured. For most of the insects there was no significant dif- on flower stigma by a given pollinator species (e.g. ference between the length of the walking distance made himack and Silander 1975) or direct measuresof seed set on inflorescences of the two subspecies. Only for T. after visits of certain pollen-carrying vectors (Motten et al. nigifrons and l,. caesar this difference was significant - 1981, Pettersson1991, Miyake and Yahara 1998). both visited approx. three times more umbellets of H. s. Unfortunately, in caseof plants with the so-called 'promis- ssp.sibiicum (t-test, p<0.001 for 7- nigifrons; p<0.002 for cuous' floral systems (Grant 1949) such as Apiaceae, the L. caesar). Hoverflies E. syrphoides visited almost 1/3 of methods cited above are inadequatebecause it is impossi- umbelletsof both subspecies(Fig.2). ble to calculate the pollinators importance index for all Comparison of the number of insect visits (no. of visits insect visitors - there are so many of them. It is also unsat- calculated as a sum of captures and video recordings) isfactory to work only with the group chosen, sim- showed significant differences between the studied sub- ply basedon floral syndromes(Waser et al. 1996). In many species of H. sphondylium (Table 1; probability of such caseseffective pollinators constitute only a small fraction distributions calculated from binomial distribution). H. s. of the total of animal species observed on the flowers of ssp. sphondylium was visited more frequently by Diptera certain plant species (Lindsey 1984; Schemske and (P<0.005), even when the taxa that carried no pollen were Horowitz 1984; Fishbein and Venable 1996). In such situa- excluded, and Hymenoptera (P=0.01), while l/. s. ssp. tions other indirect methods e.g. measuring of the pollen sibiricum was preferred by Coleoptera (P<0.005). loads carried by different vectors, observationsof their fre- Significant differences occurred also within the orders for quency, abundance and behaviour on the flowers may be individual insect taxa (Table 1). more useful. Among them photographic methods, especial- The importance of particular vectors differed also betwe- ly video techniques,have already been applied for studies en the studied subspecies(Fig. 3). The most important po- on pollination ecology of angiosperms(Keams and Inouye llinators were muscid flies Thicops nigifrons (IC=0.74 for 1993). These are extremely useful for observations of ssp. sibiicum, and 0.39 for ssp. sphondylium) and hover- species visited by many pollinating vectors - such as the flies Eiozona syryhoides (IC=0.25 for ssp. sibiicum, and umbellifers described herein. The sum of the above ele- 0.39 for ssp.sphondylium). Syrphids were the most impor- ments may make a useful description of pollination effec- tant group on H. s. ssp. sphondylium (IC=0.49), and less tiveness and importance of certain pollinators (Lindsey important on flowers of /y'. s. ssp.sibiicum (IC=0.25). The 1984; Lambom and Ollerton 2000). remaining 0.01 for H. sphondylium ssp. sibiicum accoun- Flowers of Apiaceae are generally considered primitive ted for coleopteran genusDasytes. For H. sphondylium ssp. in terms of pollination systems.Among Ihem genusHera- sphondylium more important were Arge ustulata (Hyme- cleum, and particularly H. sphondylium is said to be visited noptera; IC=0.07) and four other fly species(IC=0.05). by many dipteran taxa (Drabble and Drabble 1917,1927; The mean umbellet number per one umbel necessaryfor Karczewski 1967;GraceandNelson 1981;Sheppard 1991, calculating U from Equation I was 15.6 for H. s. ssp. sibir- hoctor. Yeo and Lack 1996). In most of the studies flower icum and 15.8 for 11.s. ssp. sphondylium (N=22). visitors were treated as pollinators (e.g. Sheppard 1991).

ssp.sphondylium I T.nigritrons

Q E.syrphoides

M M. cinctella

E A. ustulata

I othertaxa ssp.sibiticun

0.80 1.00

Fig. 3. Pollinator Importance Coefficient (IC) for insects carrying H . sphondylium pollen. For IC formula seeMethods. l6{t POLLINATIONOF HERAC LEU M SP HON DYLIU M ZychM.

However the analysis carried out by Grace and Nelson (Proctor, Yeo and Lack 1996). Surprisingly, most of polli- (1981) for H. sphondylium and H. mantegazzianum nators made similarly long visits, only I. nigifrons urd L. showed that among 80 insect taxa, captured on inflores- caeser visited three times more umbellets of ssp. sibiicum cences of both the species, only 31 carried significant (Hymenoptera visited more umbellets of ssp. sphondylium, pollen loads. However these descriptions of pollinators' but the visits were so rare that it was impossible to use any importance were only based on the estimatedpollen loads. statistical test to confirm this observation). Perhaps this A more complex approach was used in studies on repro- behaviour may be explained by the tendency to avoid the duction strategiesof Angelica and three related species predators (e.g. wasps visiting umbels for pray) - dark flies from among the American genera Thaspium and Zizia are more visible on white than on dull green flowers. (Bell and Lindsey 1978; Lindsey 1984). These surveys Apart from colours, flower scentsmay also play a major showed that despite the broad spectrum of flower visitors, role in pollination and may serye as other possible explana- only few insect species were responsible for pollination - tion of different pollinators' sets; Tollsten and Ovstedal e.g. in case of Angelica these were mainly four speciesof (1994), who studied three populations of the umbelliferean bumblebees (Bombus sp.) and other Hymenoptera (Bell Conopodium majus, showed significant differences in and Lindsey 1978), and in case of protogynotts Thaspium flower scentchemistry among them. They concluded that it "an and Zizia - solitary bees (Lindsey 1984). Also for Daucus might reflect ecotypic responseto local faunae of polli- carota the most efficient pollinators (dependingon the sea- nators". It may therefore mean that also in caseof H. spho- son) were various Diptera, Tenthredo sp. (Hymenoptera) ndylium floral features, not studied in the present paper, andRhagonycha fulva (Coleoptera) (Lambom and Ollerton acting on insects' behaviour are more subtle and need fur- 2000). This paper reports similar trends for protoandrous ther studies. 'faith- H. sphondyliumwhich suggeststhat the conceptof Although for both subspeciesthe most important pollina- ful pollinators' of Apiaceae(Bell 1971; Bell and Lindsey tors were Diptera (especially T. nigifrons and E. syr- 1978; Lindsey 1984) may be more common than previous- phoides) results of this study may indicate specialisation Iy expected. towards some particular group of insects, as the most effi- In the studies of Grace and Nelson (1981) Diptera cient on F1.s. ssp. sphondylium were syrphid flies. Perhaps accountedfor over 78Voof flower visitors to H. sphondyli- also Hymenoptera played an important role in the evolu- um in Great Britain. In my studies this number is equally tion of its pollination system.As most of montane forms of high - 807o for summarised results for both subspecies H. sphondylium and other European montane Heracleum (video and capture). Not all of these were equally efficient have white zygomorphic flowers (Brummitt 1968), one pollen carrying vectors - the most efficient were flies T. possible explanation is that this particular trait could have nigrifoms (Muscidae) and hoverflies Eiozona syrphoides, been important in attracting high-elevation pollinators such however their importance differed between the subspecies as bumblebees etc. To confirm this assumption further studied. The former was also observed by Grace and studies are necessary,as it is impossible to state whether Nelson (1981) and was described as carrying significant this trend is constantin consecutiveseason; it was postulat- pollen loads. While I. nigifrons was the major pollinator ed by Waser et al. (1996) and showedby Henera (1988, for H. s. ssp. sibiicum, its efficiency was equal to E. syr- 1995, 1996) for Lamiaceae, Fishbein and Venable (1996) phoides in caseof H. s. ssp.sphondylium. Also the diversi- for Asclepias, and Lambert and Ollerton (2000) for Daucus ty of pollen-carrying vectors was higher for this taxon (this carota, that the key pollinators' abundance may vary included M. cinctella, A. ustulqta and four other flies). between seasons.It seems also plausible that, possibly Other insect species, although sometimes abundant (as becauseof the changing geographical range, this situation 'peak', Meligethes sp.), or carrying large pollen loads (S. is just a result of an ancient adaptative common for maculata) were not important pollinators, either because many Apiaceae, that no longer has a great functional they were incapable of carrying pollen (Meligethes sp. - importance to this species (Bell 1971) - similarly to the perhapsbecause of small size and behaviour on the flower) significance of the dark central floret found in Daucus or were very rare visitors. carota (Lunbom and Ollerton 2000). Eartier studies for Many authors indicate that the existence of morphologi- Poland (Gawlowska 1956,1957) restrict the distribution of cally different forms of the same species may imply the H. s. ssp. sphondylium to the southem part, and H. s. ssp. usage of different pollinators' sets which leads to specia- sibiicum to the northem part of the country. However my tion (Kay 1976;Henera 1996). However the colour is not observationsshow that both taxa can be found in different always the only clue for different pollinator behaviour. In regions. Perhapsin places of origin of the two forms, local- case of two colour morphs of Delphinium nelsonii wh\te ly important insect groups existed that favoured certain flo- 'nectar flowers did not posses guides'that attractedinsects ral features and the selective pressure led to nowadays and hummingbirds to blue flowers (Waser and Price 1983). existing taxa. Also the size of inflorescence (Brody and Mitchell 1997) and its compactness(Bell 1971) may be of great value in attractivenessfor pollinators. As showed in this terms of ACKNOWLEDGEMENTS paper, it is also true for H. sphondylium, becauseH. s. ssp' sphondylium, with its showy and compact inflorescences, I would like to thank Prof. A. Draber-Moriko, Dr. A. was significantly more attractive for Diptera and Krzysztofiak, and Dr P. Tykarski for insect identification, Hymenoptera. This is consistent with the general assump- and Wigry National Park for the possibility of conducting tion that Diptera and Hymenoptera are more attracted by field research.Krzysztof Spalik made valuable comments white than greenish flowers, whereas Coleoptera generally on (he manuscript, and Ingeborga Jarzynahelped with sta- prefer flowers with dull colours (brownish and greenish) tistics. This work would have not been done without con- Vol.71, No. 2: 163-17O,2002 ACTA SOCIETATIS BOTAMCORUMPOLONIAE 169

stant support from Hanna Werblan-Jakubiec. The studv JOHNSON S.D., DAFNI A. 1998. Responseof bee_fliesro rhe was supported financially by Granr Bw-1420/ggl5 from shape and pattem of model flowers: implications for floral Faculty of Biology, Warsaw University. evolution in a Mediterranean herb. Functional Ecol. 12: 2g9_ 297. JOHNSON S.D., STEINER K.E. 2000. Generalization versus LITERATURE CITED specializationin plant pollination systems.TREE 15: 140_143. KARCZEWSKI J . 1967. Obserwacje nad much6wkami (Diptera) BEATTIE A.J.1971. pollinarion mechanismsinViola. phv_ New z rodzin Tachinidae i Calliphoridae tol. 70: 343-360. odwiedzaj4cymi kwiaty. Fragm.Faun. 13:407-484.(in polish) BELL C.R., LINDSEY A.H. 1978.The umbel as a reproducrive KAY Q.O.N. 1976. Preferential pollination of yellow_flowered unit in the Apiaceae. 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BIOLOGIA ZAPYLANIA HE RAC LEU M SP H ON DY U UM L. (APIACEAE): owYZSZoScI srerycH KwIAT6w I ZWARTYCH KWIATOSTAN6W

STRESZCZENIE

W niniejszej pracy postawiono dwa pytania: (1) Jakie owady zapylaj4 kwiaty dw6ch gatunk6w H. sphondy- lium?, oraz (2) Czy badane ro6liny posiadaj4 takie same zespoly owad6w zapylaj4cych, czy moLe s4 atrakcyjne dla r62nych owad6w? Badania wykazaly,2e spo6r6d40 takson6w owad6w odwiedzaj4cych obydwa podgatunki barszczu zwyczajnego, zaledwie okolo 53Voprzenosilo znacz1ce ladunki pylku. Obliczony dla ka2dej grupy owa- d6w wsp6lczynnik wagi zapylaczy (Pollinator Importance Coefficient), oparty na obserwacjachaktywno$ci owa- d6w oraz przenoszonychladunkach pylku, ujawnil, 2e tylko dwa gatunki w przypadku l/. s. ssp. sibiicum (Thi- cops nigifrons, Eriozona syrphoides) oraz cztery w przypadku H. s. ssp. sphondylium (7. nigifrons, E. syrphoi- des, Meliscaeva cinctella oraz Arge ustulata) s4 rzeczywiScieodpowiedzialne za zapylanie. Mimo, 2e oba badane podgatunki byly odwiedzaneptzezzbliLone zespoly zapylaczy,podgatunek nominatywny, o charakterystycznych bialych i zwartych baldachach,byl odwiedzany czg(ciej przez much6wki i blonk6wki, natomiast lulne zielonka- we kwiatostany podgatunku syberyjskiego czg(r;iej odwiedzaly chrz4szcze,Praca wskazuje, 2e koncepcja wier- nych zapylaczy mo2e tak2e odnosii sig do szerszegospektrum baldaszkowatych (Apiaceae), uwa2anych zwykle za roSliny prymitywne pod wzglgdem system6w zapylania,oraz sugeruje moZliwe drogi r6Znicowania sig dw6ch blisko spokrewnionych takson6w.

SLOWA KLUCZOWE: Hemcleum sphondylium L., Diptera, morfy barwne, zapylanie, wagazapylaczy.