Received: 19 September 2018 Revised and accepted: 11 December 2018 DOI: 10.1111/1442-1984.12231

ORIGINAL ARTICLE

Specialized pollination by honeybees in dayanum, a fall–winter flowering orchid

Yoshiyuki Matsuda | Naoto Sugiura

Department of Biological Sciences, Graduate School of Science and Technology, Abstract Kumamoto University, Kumamoto, Japan Floral biology and pollination mechanisms of Cymbidium dayanum, an endangered Correspondence epiphytic orchid, were investigated in south Kyushu, Japan. The flowering period Naoto Sugiura, Faculty of Science, Kumamoto spanned approximately 4 months from fall to winter, with the inflorescences often University, Kumamoto 860-8555, Japan. Email: [email protected] blooming asynchronously on each and individual flowers commonly lasting for a month. The nectarless flowers are self-compatible but cannot autonomously self-pollinate; the orchid needs to attract pollinators by deceit for capsule produc- tion. The field observations showed that the flowers were pollinated exclusively by the Japanese honeybee Apis cerana japonica, despite its long flowering period. The worker bees pollinated flowers and/or received the pollinarium on the thorax, while escaping from the labellum chamber. The natural fruit-set ratios at the popu- lation level, an estimate of pollination success, varied interannually but were gener- ally low, as the result of infrequent flower visits by honeybee workers owing to the cold winter climate and the lack of a nectar reward. Because most flowers that were artificially pollinated in the winter successfully developed into capsules, the cold- ness was not considered a direct cause of the low fruit-set ratios. Our results explic- itly indicate that the bee pollination niche could be available to temperate plant species even during mid-winter. We inferred advantages for the winter flowering of C. dayanum.

KEYWORDS Apis, cymbidium, deceptive pollination, flowering season, winter climate

1 | INTRODUCTION pollination, generalized food deception, and Batesian food-source mimicry. To date, autonomous self- Cymbidium Sw. (: ) includes pollination has been reported in C. macrorhizon Lindl, approximately 52 species naturally distributed in Asia and C. nipponicum (Franch. et Sav.) Rolfe [as C. aberrans Oceania (Du Puy & Cribb, 2007; Pridgeon, Cribb, Chase, & (Finet) Schltr.], and C. nagifolium Masam. (as C. lancifo- Rasmussen, 2009). This taxon includes epiphytic, lithophy- lium Hook.), all of which lack a rostellum that functions tic and terrestrial species, which thrive in a variety of habi- as the physical barrier between the anther and stigma tats, such as open savannas, tropical rain forests and (Suetsugu, 2015). Reward-based pollination takes place in high-elevation grasslands (Pridgeon et al., 2009). Most C. mandidum Lindl., in which flowers are pollinated by species are autotrophic and rarely mycoheterotrophic the stingless bee Trigona kockingsi, which collects viscid (Motomura, Selosse, Martos, Kagawa, & Yukawa, 2010; substances on the labellar surface (Macpherson & Rupp, Suetsugu, 2015). 1935, cited in Du Puy & Cribb, 2007). The substance is In Cymbidium orchids, there are four known modes of probably used as a nest-building material. A similar mode pollination: autonomous self-pollination, reward-based is also thought to occur for C. lowianum (Rchb.f.) Rchb.,

Plant Species Biol. 2019;34:19–26. wileyonlinelibrary.com/journal/psbi © 2019 The Society for the Study of Species Biology 19 20 MATSUDA AND SUGIURA in which the labellar surface has protein-containing papil- 2 | MATERIALS AND METHODS lae that may function as food hairs (Davies, Stpic- zynska, & Turner, 2006). Generalized food deception has 2.1 | Study sites been found for some species, including C. lancifolium Because Japanese C. dayanum is now considered nearly (Cheng, Liu, He, Wei, & Luo, 2007), C. goeringii (Rchb. extinct in the wild, mainly as a result of overexploitation f.) Rchb.f. (Tsuji & Kato, 2010; Yu, Luo, & Dong, 2008) (Inoue, 2015), we did not find a natural population appropri- and C. kanran Makino (Sugawara & Tsutsui, 1998; ate for study. Thus, field observations were conducted at Tsuji & Kato, 2010). The nectarless flowers attract polli- two seminatural habitats (sites N and K) located near rem- nating bees by visual and olfactory stimuli. Finally, nant broad-leaved evergreen forests (past habitats) in south Batesian food-source mimicry occurs in C. insigne subsp. Kyushu, Japan. At both sites, orchid seedlings of various seidenfadenii P.J. Cribb & Du Puy. The plant relies exclu- sizes were present, suggesting that the series of events neces- sively on the bumblebee Bombus eximius, which also pol- sary for sexual reproduction, including pollination, were linates the nectar-producing flowers of Rhododendron occurring successfully. One site was in the grounds of the ciliicalyx subsp. lyi (H. Lév.) R.C. Fang Noborio Elementary School (site N), Minami-Osumi Town, (as Rhododendron lyi Leveille) (Kjellsson, Rasmussen, & Kagoshima Prefecture, where six adult C. dayanum grew on Dupuy, 1985). Because both have a similar floral six trees (but one was seriously damaged by a typhoon in appearance, the bumblebees occasionally mistakenly visit late September 2016). Approximately 20 km east-northeast of site N, the second site was in the grounds of Kishira Ele- the nectarless flowers of the orchid. In addition to the mentary School (site K), Kimotsuki Town, Kagoshima Pre- above-mentioned modes, insect pheromone mimicry may fecture, where three adult plants grew on three trees. At both be used by C. floribundum Lindl. (as C. pumilum Rolfe) sites, the trees were well isolated from each other, resulting under cultivated conditions, which has flowers that are in the orchids usually receiving sunlight daily for moderately exclusively pollinated by the Japanese honeybee Apis cer- long hours. No nectariferous flowers that resembled C. daya- ana japonica (Apoidea: Apiformes: Apidae) (Sasaki, num flowers were found at the study sites or nearby broad- Ono, & Fukuda, 1992; Sasaki, Ono, & Yoshida, 1991). leaved evergreen forests. The nectarless flowers emit a scent that includes two man- dibular gland components of the honeybee, 2.2 | Flowering habits and functional morphology of 3-hydroxyoctanoic acid and 10-hydroxy-(E)-2-decenoic flowers acid, to deceive individual bees or bee swarms into engag- At site N, the number of opening flowers on inflorescences ing in pollination activity (Sugahara, Izutsu, Nishimura, & (n = 126 inflorescences in the 2016–2017 flowering season; Sakamoto, 2013). n = 155 inflorescences in the 2017–2018 season) was C. dayanum Rchb.f. is distributed in Asia, from the recorded intermittently to clarify the flowering phenology. Himalayas of northern India to Japan and south through We also carefully studied functional features of flowers and Indo-China and the Philippines to Indonesia, and prefers inflorescences, which may be important for pollinator attrac- cooler, higher elevations of about 1,000–1,500 m in its tion and manipulation, with natural plants at site N and four southern distribution area (Du Puy & Cribb, 2007). How- cultivated plants on the campus of Kumamoto University, ever, despite its wide distribution, to our knowledge, no Kumamoto City, central Kyushu. To examine the lifespan of information on the pollination strategy is available. individual flowers, some floral buds of the cultivated plants Recently, we investigated the floral and pollination biol- were individually marked, and the opening and wilting dates ogy of this epiphytic cymbidium in south Kyushu, Japan, for each were recorded during the two flowering seasons where it flowers between October and December (n = 24 flowers of 10 inflorescences in the 2016–2017 sea- (Yukawa, 2015). The main aims of our study were: (a) to son; n = 69 flowers of 12 inflorescences in the 2017–2018 investigate the floral features of C. dayanum from a season). functional perspective, an aspect rarely examined thus To examine whether C. dayanum is self-compatible and far, (b) to identify the pollinator and characterize its whether it is pollinator dependent, 33 intact flowers were intrafloral behavior, and (c) to examine the natural fruit- selected randomly on October 21, 2016 at site K. Each set ratio, which is an indicator of pollination success. On flower was subjected to one of the following treatments: the basis of the results, we discuss the pollination strat- (a) self-pollination with one pollinarium from the same egy of Japanese C. dayanum, including possible reasons flower; (b) cross-pollination with one pollinarium from a why this orchid continues to flower in winter when flower of a different plant; or (c) no pollination. The perianth almost all bee species have already ceased their extra- segments of all the treated flowers were then trimmed off to nest activities (Ikudome, 1992; Y. Matsuda, personal prevent natural pollination (Li, Zheng, Dafni, & Luo, 2010; observation, 2016–2018). Sugiura, 2013; Sugiura, 2014). On January 18, 2017, the MATSUDA AND SUGIURA 21 flowers were checked to determine whether their ovaries had asynchronously. Within an inflorescence, about 12 flowers developed into swollen green capsules. For each treatment, (11.4 ± 2.2, n = 126 in the 2016–2017 season; 12.1 ± 3.3, we calculated the fruit-set ratio (i.e., the ratio of swollen cap- n = 155 in the 2017–2018 season) opened sequentially, but sules to treated flowers). Furthermore, 16 flowers were self- all of the flowers bloomed simultaneously for some time pollinated in late December 2017 to ascertain whether because the individual flowers were long-lived pollinated flowers could normally develop into capsules (30.0 ± 6.5 days, n = 24 flowers of 10 inflorescences in the under cold winter conditions, and their fruiting success was 2016–2017 season; 30.3 ± 7.3 days, n = 69 flowers of examined in late February 2018. 12 inflorescences in the 2017–2018 season). The floral life- span varied seasonally, becoming longer with later flower- 2.3 | Flower visitors and their behaviors opening dates (r = 0.68, n = 69, p < 0.001), and the most long-lived flowers were open for 51 days. On the contrary, At site N, for 3–8 hr per day, a tree with flowering C. daya- pollination invariably shortened the floral lifespan. On the num was monitored to observe intrafloral behaviors of second to third days after pollination, the perianth was flower visitors, which consist of four stages: approaching, unchanged, but the stigma closed, enveloping the deposited alighting, entering and exiting (Nilsson, 1979). On some pollinia (Figure 2a). On the fifth day, the perianth withered occasions, flower-visiting behavior was also recorded by a and closed, whereas the ovary slightly, but distinctly, camcorder (Handycam HDR-SR1, Sony, Tokyo, Japan) and increased in length. Of the 16 flowers that were artificially the video footage was carefully examined later. These obser- self-pollinated in late December, 14 flowers (87.5%) suc- vations took place between 8:00 a.m. and 5:00 p.m. over a cessfully developed into capsules. period of 66 days during the two flowering seasons, for a The flowering inflorescences were usually pendent, so as total of 284 hr. not to be hidden by foliage (Figure 2b). Each flower, which was laxly arranged on an inflorescence, was usually directed 2.4 | Fruiting habits and natural fruit-set ratios horizontally on the basal portion of the inflorescence but To track capsule growth, we intermittently observed the nat- obliquely or completely downward on the anterior portion, ural and cultivated plants. At site N, flower scars and green making the entire flowering inflorescences visible from a capsules per scape were counted to calculate fruit-set ratios distance. on March 12, 2017 and February 26, 2018. The nectarless flowers (Figure 2c), approximately 3.5 cm in width, were usually unscented, although flowers in patches of sunlight were occasionally faintly scented. The 3 | RESULTS three sepals were greatly spread, visually advertising the flowers themselves, whereas the two lateral petals protruded 3.1 | Flowering habits and functional morphology of forward or were occasionally slightly spread. The labellum flowers comprised two lateral lobes and one mid-lobe. The well- defined lateral lobes were erect and loosely embraced the At site N, the flowering period of C. dayanum lasted approx- column, forming a labellum chamber into which pollinators imately 4 months in the fall and winter seasons, with a peak enter to seek floral rewards. The mid-lobe had a strongly in November, and a small number of flowers was still pre- recurved apex, and its inner surface was covered with minute sent the next January (Figure 1). Each plant produced 8–46 hairs, with two raised longitudinal ridges where many papil- racemous inflorescences (mean 25.2, n = 5 in the lae occurred. The arched column was slightly shorter than 2016–2017 flowering season), many of which flowered the lateral lobes, with the anther at its apex. Two solid polli- nia were attached to an oblong viscidium. The sticky stigma located behind the anther was concave, with its upper mar- gin forming a rostellum. Extrafloral nectaries were found on bracts, floral buds and opening flowers, which attracted ants, including Technomyrmex brunneus, Paratrechina flavipes and Formica hayashi. The sepals and lateral petals were translucent but white in appearance, each having a deep red longitudinal line on both surfaces. The inner surface of the labellum was deep red, except for a large yellow marking in the center and sev- eral white slanting stripes on the lateral lobes. The column was entirely dark red, except for the yellow anther cap, FIGURE 1 Flowering phenology of Cymbidium dayanum in 2016–2017 (closed circles and dashed lines) and 2017–2018 (open circles and solid thereby visually uniting the column and labellum, which lines) at site N (Minami-Osumi town, Kagoshima Prefecture, Japan) compose the labellum chamber. As a whole, the flower had 22 MATSUDA AND SUGIURA

FIGURE 2 Some functional aspects of Cymbidium dayanum flowers. (a) A closed stigma that has successfully received pollinia. (b) Flowering inflorescences. (c) Individual flowers. (d) A previous season's swollen capsule among flowering inflorescences a radiating-stripe pattern that induced pollinators to enter the this honeybee species is presumed to be a pollinator of natu- labellum chamber (Figure 2c). ralized C. dayanum on the Hawaiian Islands (Ackerman, Cross-pollinations resulted in 87.5% (7/8) fruit-set ratios, Falcón, & Recart, 2011). whereas 70.0% (7/10) of the self-pollinations were success- Among the flower visitors, only the Japanese honeybee ful in setting capsules. Consequently, the cross-pollinated consistently behaved in a manner on C. dayanum flowers and self-pollinated flowers did not differ significantly with that resulted in contact with the anther and stigma. A worker respect to fruiting success (Fisher's exact probability test, honeybee usually alighted on the recurved portion of the P > 0.05). Unpollinated flowers produced no cap- labellum just after reducing its flight speed, and then it sules (0/15). entered the labellum chamber to seek nectar (Figure 3a). After staying for a short time (1–13 s, mean 6.2, n = 23), 3.2 | Flower visitors and their behaviors the bee backed out, during which the pollinarium removal At site N, only five insect species, belonging to one dipteran, occurred. As the retreating individual stood firm with one lepidopteran and two hymenopteran families, were extended hind legs on the recurved portion of the labellum, recorded as flower visitors of C. dayanum (Table 1). The its abdomen was often directed downward, but the thorax most frequently observed species was the Japanese honeybee was kept in a nearly horizontal position, pushing the scutel- (78/87), and none of the worker bees had pollen loads on lum against the rostellum (viscidium) (Figure 3b), resulting their corbiculae, indicating that they were nectar foragers. in the pollinarium, together with the anther cap, adhering to No flower visits by the introduced western honeybee Apis the bee (Figure 3c). After the first flower visit, honeybees mellifera were observed during the study period, although usually flew away, without visiting another flower.

TABLE 1 Flower visitors of Cybidium dayanum at site N (Minami-Osumi town, Kagoshima Prefecture, Japan)

Order Family Species 2016–2017 2017–2018 Diptera Syrphidae Betasyrphus seraritus 50 Metasyrphus confrater 20 Lepidoptera Sphingidae Macroglossum sp. 1 0 Hymenoptera Vespidae Vespula flavipes lewisii 01 Apidae Apis cerana japonica 47 31 MATSUDA AND SUGIURA 23

FIGURE 3 Apis cerana japonica entering a Cymbidium dayanum flower and leaving with the pollinarium from the flower

Of the 78 honeybee observations, the worker bees were lewisii entered the labellum only slightly and then observed to alight on C. dayanum flowers on only flew away. 37 (47.4%) occasions. Once the individuals had alighted, however, they frequently entered the labellum chamber 3.3 | Fruiting habits and natural fruit-set ratios (28/37, 75.7%) and then successfully removed pollinaria During the flowering period, the previous season's capsules (19/28, 67.9%). Because three of the 37 flowers visited had had not yet dehisced on both natural and cultivated plants; already removed their pollinaria, 25.3% (19/75) was they were swollen but green and hard (Figure 2d). In mid to regarded as the frequency of pollen removal by the Japanese late April, large capsules on cultivated plants started to honeybee. Also, on at least 13 occasions at their first appear- dehisce, and seed dispersal had already finished by late May ances on C. dayanum plants, the honeybees already bore one on natural plants at site N. Thus, the flower-to-capsule devel- or two C. dayanum pollinaria (mean 1.3, n = 12). On three opment was completed in 19 months, as a maximum. In the (23.1%) of those occasions, the bees entered the chamber – – and then successfully pollinated flowers. Therefore, the fre- 2016 2017 and 2017 2018 seasons, the fruit-set ratios at quency of the successful pollination by the Japanese honey- site N were 7.4% (n = 1,443 flowers on 126 inflorescences) bee was roughly estimated as 5.8% using the two values. and 3.9% (n = 1,867 flowers on 155 inflorescences), respec- Table 2 shows monthly changes in the observed fre- tively, with the difference being significant between the sea- quency of Japanese honeybee visits to C. dayanum flowers sons (chi-squared test, p < 0.001). The numbers of fruits per – – (the number of individuals per plant per hour). Although the inflorescence were 0 3 (mean 0.9, n = 126) and 0 6 (mean values distinctly decreased later in the flowering season, the 0.5, n = 155), respectively, and 37.0% and 65.8%, respec- worker honeybees were observed to visit the flowers during tively, of the inflorescences examined bore no capsules. both winters. At the study sites, no honeybee workers that visited native flowers other than the orchid were observed. 4 | DISCUSSION Two hoverfly species, Betasyrphus serarius and Meta- syrphus confrater, were observed to alight on the labellum In south Kyushu, Japan, the flowering period of C. dayanum several times but did not enter it. A hovering individual of spanned approximately 4 months from fall to winter, with the hawkmoth Macroglossum sp. inserted its long thin pro- the inflorescences often blooming asynchronously on each boscis into the labellum chamber but the pollinarium was plant and individual flowers commonly being open for a Vespula flavipes not removed. A worker of the yellow jacket month. In addition, the floral lifespan became distinctly lon- ger in the winter. Such extended flowering may be advanta- TABLE 2 Monthly changes in the frequency of Japanese honeybee visits geous, in terms of increasing the number of outcrossing to Cymbidium dayanum flowers (individuals per plant per hour) at site N partners, reducing geitonogamy, and lowering the risk of (Minami-Osumi town, Kagoshima Prefecture, Japan) infrequent pollinators and periods of bad weather Study months Study years (Willmer, 2011). Oct Nov Dec Jan Despite its self-compatibility, C. dayanum cannot auton- — 2016 0.44 0.25 0.26 omously self-pollinate. Thus, the flowers need pollinators to — 2017 0.84 0.04 0.08 set capsules even in winter when flower-visiting insects are ——— 2018 0.08 very scarce. The flowers on pendant inflorescences visually 24 MATSUDA AND SUGIURA attract pollinators and pollinated flowers promptly wither, seed dispersal (Aizen, 2003). The workers can forage when which directs pollinators to as-yet-unpollinated flowers. Our the ambient temperature is approximately 10C, even in observations reported here indicate that only the Japanese winter (Sakai, 1996; Matsuda Y., unpublished data), but honeybee, by far the most frequent flower-visiting species, is they faced a great scarcity of native floral resources at the a legitimate pollinator of Japanese C. dayanum, despite the orchid habitats. Under such circumstances, worker honey- long flowering period. The nectar-seeking workers did not bees that eagerly exploit new floral resources may be more necessarily alight on C. dayanum flowers with a high fre- prone to visit rewardless flowers of C. dayanum. Flowering quency; however, they were actually observed to remove during the cold season may also be advantageous, in terms pollinaria and then deposit pollinia onto the stigma, whereas of reducing competition among co-blooming plants for the the other four observed insect species did not. After foraging honeybee, warding off undesirable flower visitors and on a C. dayanum flower, most workers immediately flew extending the floral lifespan (cf. Dafni, 1996), because our away and disappeared from view. This observation, together observations indicate that there were no native nectarifer- with the observation that some individuals already bore pol- ous plants available to honeybees, flower-visiting insects linaria at their first appearances on C. dayanum plants, other than the Japanese honeybee were very few, and the suggests that the Japanese honeybee occasionally cross- floral lifespan became distinctly longer in the winter. Alter- pollinates flowers. natively, winter coldness definitely restricted honeybee for- Although some temperate winter-flowering plants aging activity, indirectly affecting the pollination success depend on birds for pollination (e.g., Aizen, 2003, Tristerix of the orchid. Mart.; Fang, Chen, & Huang, 2012, Eriobotrya Lindl.; Sun, Natural fruit-set ratios of C. dayanum at the population Huang, Chen, & Huang, 2017, Camellia L.), the present level differed between the two flowering seasons but were study is the first to fully document specialized pollination by both low. As many as from one-third to two-thirds of inflo- honeybees in fall–winter flowering plants, and thereby it rescences failed to produce capsules in each season. Such explicitly indicates that the bee pollination niche could be low reproductive outputs are well known among rewardless available to temperate plant species even during mid-winter. orchid species (Tremblay, Ackerman, Zimmerman, & Japanese C. dayanum plants have the following floral mor- Calvo, 2005). In winter-flowering C. dayanum, in addition phological traits that appear to reflect specialized pollination to the lack of floral rewards, the flowering season is also a by A. cerana japonica: (a) the dimensions of the labellum primary cause of the low fruit-set ratios. However, coldness chamber, formed by the column and labellum, correspond to is not considered a direct cause of the low ratios, as most the body size of the worker honeybee; (b) the strongly flowers that were artificially pollinated in the winter suc- recurved apex of the labellum enables the precise deposition cessfully developed into capsules. Because of the capsules' of pollinaria on the honeybee's scutellum; and (c) the oblong large size and long development period, the high fruit-set viscidium is appropriate for adhering to the scutellar surface. ratio may actually reduce the subsequent growth of the In addition, the color pattern on the perianth may function as orchid plants. an effective visual stimulus to A. cerana japonica, because Among the 27,000 species of Orchidaceae, specialized the western honeybee and its allies (some species of bumble- pollination by honeybees is not common, in marked contrast bees and stingless bees) are known to innately prefer radial with the prevalence of specialized pollination by the other markings (Benard, Stach, & Giurfa, 2006; Biesmeijer et al., corbiculate Apidae (orchid bees, bumblebees and stingless 2005; Orbán & Plowright, 2014). Although A. cerana japon- bees) (van der Pijl & Dodson, 1966; van der Cingel, 1995, ica is endemic to Japan, the eastern honeybee A. cerana s. l. 2001), even though honeybees are widely distributed in Eur- is widely distributed in Asia, having a distribution range asia and Africa, with each colony containing a few thousand (Sasaki, 1999) that overlaps the entire distribution range of to 60,000, or more, workers (Michener, 2007). However, the C. dayanum (Du Puy & Cribb, 2007). Therefore, the orchid honeybee pollination seems exceptionally widespread may rely on various subspecies of the eastern honeybee for among Cymbidium species, including C. floribundum pollination across its entire range. (Sasaki et al., 1991; Sasaki et al., 1992; Sugahara et al., C. dayanum offers no nectar or other reward to pollinat- 2013), C. suavissimum Sander ex C.H. Curtis (Sugahara, ing honeybees, and there were no nectar-producing flowers 2006), C. atropurpureum (Lindl.) Rolfe [as C. pendulum that resembled the orchid flowers at the study sites and pre- (Roxb.) Sw.] (Attri & Kant, 2011; Verma et al., 2012), vious habitats. Therefore, this orchid adopts a generalized C. finlaysonianum Lindl. (Burkill, 1919; Chan, Lamb, Shim, & food-deception strategy, which is the most widespread Wood, 1994; Ong, 2010), C. devonianum Paxton (Sugahara, mode of floral deception in orchids (Jersáková, Johnson, & 2006), C. dayanum (this study), a local population of Chi- Kindlmann, 2006; Nilsson, 1992). Regarding this honeybee nese C. goeringii (Yu et al., 2008; see Tsuji & Kato, 2010 pollination by deceit, we suspect that the flowering season, for Japanese populations), C. kanran (Sugawara & Tsutsui, which spans the coldest time in Japan, may be a crucial ele- 1998; Tsuji & Kato, 2010) and C. lancifolium (Cheng et al., ment, although it may be keyed to an appropriate time for 2007), although origin of the honeybee pollination awaits MATSUDA AND SUGIURA 25 further observations on natural pollination of more Cymbid- Kjellsson, G., Rasmussen, F. N., & Dupuy, D. (1985). Pollination of Den- ium species and their evolutionary relationships. It is hoped drobium infundibulum, Cymbidium insigne (Orchidaceae) and Rhodo- dendron lyi (Ericaceae) by Bombus eximius (Apidae) in Thailand: A that the findings reported here will encourage researchers to possible case of floral mimicry. 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