Geographic Variation in the Pollination Biology of Passiflora Lutea (Passifloraceae) J
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Journal of the Arkansas Academy of Science Volume 62 Article 7 2008 Geographic Variation in the Pollination Biology of Passiflora lutea (Passifloraceae) J. Burks Holland University of Arkansas at Little Rock J. Lanza University of Arkansas at Little Rock, [email protected] Follow this and additional works at: http://scholarworks.uark.edu/jaas Part of the Botany Commons Recommended Citation Holland, J. Burks and Lanza, J. (2008) "Geographic Variation in the Pollination Biology of Passiflora lutea (Passifloraceae)," Journal of the Arkansas Academy of Science: Vol. 62 , Article 7. Available at: http://scholarworks.uark.edu/jaas/vol62/iss1/7 This article is available for use under the Creative Commons license: Attribution-NoDerivatives 4.0 International (CC BY-ND 4.0). Users are able to read, download, copy, print, distribute, search, link to the full texts of these articles, or use them for any other lawful purpose, without asking prior permission from the publisher or the author. This Article is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for inclusion in Journal of the Arkansas Academy of Science by an authorized editor of ScholarWorks@UARK. For more information, please contact [email protected], [email protected]. Journal of the Arkansas Academy of Science, Vol. 62 [2008], Art. 7 Geographic Variation in the Pollination Biology of Passiflora lutea (Passifloraceae) J. Burks Holland1,2 and J. Lanza1,3 1Biology Department, University of Arkansas at Little Rock, 2801 South University, Little Rock, Arkansas 72204 2Present address: 3514 Steel Bridge Road, Benton, Arkansas 72015 3Correspondence: [email protected] Abstract include red (e.g., P. coccinea), purple (e.g., P. menispermifolia), greenish-yellow (e.g., P. coriacea), Like most species of Passiflora, P. lutea is reported and white (e.g., P. costaricensis). The corona may to produce one-day flowers with complicated floral consist of one (e.g., P. citrina), or two (e.g., P. biflora), movements and requires deposition of non-self pollen or more (e.g., P. caerulea) series of filaments; the for fruit production. Medium sized bees are the most filaments may be long (e.g., P. quadrangularis) or likely pollinators in central Texas. We report on a short (e.g., P. coriacea). series of observations and experimental manipulations In most species, the reproductive parts change their that compare the reproductive biology of P. lutea in orientation after the flower opens. In these cases, the central Arkansas to that reported previously from styles point upward when the flower opens but later plants about 800 km distant in central Texas. We bend (deflex) so the stigmas move downward. These observed floral movements and floral visitors, movements bring the stigmas near visiting pollinators compared fruit production of flowers available to and appear to promote outcrossing (Janzen 1968). The pollinators versus flowers from which pollinators were details of these movements differ among species. For excluded, and compared fruit production of flowers example, style movements are completed within 20 that were hand-pollinated with self pollen versus min of opening in Passiflora foetida (Janzen 1968) but flowers that were hand-pollinated with non-self pollen. are not completed in a second unidentified species until Floral movements were similar to those of other about 5 h after opening (Janzen 1968). Passiflora Passiflora, with flowers opening for one day and styles vitifolia is intermediate to these two species, with that usually deflexed to a level below the anthers, styles that begin deflexing 30-180 min after opening presumably facilitating cross-pollination. Some and taking up to 2 h to finish moving (Janzen 1968). flowers (20%) had styles that did not fully deflex. The diversity in floral morphology is accompanied Movement of floral parts of plants in central Arkansas by a diversity in pollen vectors. The red flowers of occurred slightly earlier than in plants in central Texas. Passiflora vitifolia (Janzen 1968, Snow 1982), P. Unlike what was observed in a small sample in Texas, speciosa (Varassin et al. 2001), and P. coccinea (Storti we observed a low level of self-compatibility in P. 2002) are pollinated by hummingbirds. In contrast, P. lutea. In contrast to the medium sized bees that were foetida, an ill-odored species producing small flowers the important pollinators in central Texas, (6 cm) that are white, pink, purple, or blue, is Anthemurgus passiflorae, a small specialized andrenid pollinated by large bees (Ptiloglossa spp.) (Janzen bee that only forages on P. lutea, was likely the most 1968, Amela Garcia 1998). Large bees also pollinate important pollinator in central Arkansas. Finally, fruit Passiflora amethystina, P. miersii (Koschnitzke and set of plants in central Arkansas was much higher than Sazima 1977), and P. caerulea (Amela Garcia and Hoc that reported for plants in central Texas. Thus, this 1997). Bats pollinate P. penduliflora (Kay 2001), P. species varies geographically in its reproductive galbana (Varassin et al. 2001), and P. mucronata biology. (Sazima and Sazima 1998, Varassin et al. 2001). Passiflora incarnata, with purple, mauve, or white Introduction flowers, is pollinated primarily by Xylocopa bees (May and Spears 1988). Although all passionflowers (Passiflora spp.) Most species of Passiflora appear to require animal produce complex flowers with structural similarities, pollination and to be self-incompatible. May and species vary substantially in flower color and in the Spears (1988) excluded insect visitors from 52 flowers detail of flower structure and behavior. All species in of P. incarnata; fruit production in these flowers was this tropical and subtropical speciose genus have at 0%, in contrast to a fruit production rate of 17% in least one ring of filaments (the corona) around a flowers open to insect visitors. They also hand- vertical stalk that supports the stamens and styles (the pollinated flowers with self and non-self pollen. None androgynophore) (Vanderplank 1991). Flower colors of the flowers pollinated with self-pollen produced Journal of the Arkansas Academy of Science, Vol. 62, 2008 Published by Arkansas Academy of Science, 2008 32 32 Journal of the Arkansas Academy of Science, Vol. 62 [2008], Art. 7 Geographic Variation in the Pollination Biology of Passiflora lutea (Passifloraceae) fruit, but 80% of the flowers pollinated with non-self Methods pollen produced fruit. Similarly, Snow (1982) saw no fruit set in 30 self-pollinated flowers of P. vitifolia, and Passiflora lutea grew at sites located both on the Varassin et al. (2001) saw no fruit production in self- campus of the University of Arkansas at Little Rock pollinated flowers of P. alata (N = 27), P. galbana (N and throughout the city. Because P. lutea spreads = 25), P. mucronata (N = 56), and P. speciosa (N = vegetatively, we considered each “clump” a single 18). Animal pollinators are also required in P. individual. We conducted observations of pollinators in coccinea (Storti 2002), P. alata (Koschnitzke and June-August 1994 and 1997; we conducted Sazima 1997), P. amethystina, and P. moersii experimental manipulations in June-August 1994- (Koschnitzke 1997). In contrast, P. suberosa and P. 1996; we conducted additional observations of style capsularis (Koschnitzke and Sazima 1997) and P. movements in July 2005. All times are Central foetida (Amela Garcia and Hoc 1998) are self- Daylight Savings Time. compatible. Passiflora caerulea exhibits a “low We observed floral movements in 1994 and 2005. degree of self-compatibility” (Amela Garcia and Hoc For three days in 1994, observations began 30 min 1997). before sunrise and ended 30 min after dark. During the In addition to between-species variation, some course of the day, we watched the plant in 2-3 h shifts, species of Passiflora exhibit substantial within-species with 30-60 min breaks between observation periods. variation in floral morphology and behavior. For During this time, we recorded the movement of floral example, P. incarnata varies in color from lavender to parts through drawings. In 2005, we observed mauve to white. Although most flowers of this species Passiflora lutea flowers to assess the percentage of open in late morning, in some flowers the stigmas flowers with non-descending (non-deflexing) styles. immediately begin to deflex while in other flowers the Between 1230 and 0130, we counted and categorized stigmas never deflex (May and Spears 1988). The styles on seven plants as fully deflexed (stigmas below cultivated P. edulis also varies in self-compatibility; the anthers), partially deflexed (stigmas at the same the purple strain is self-compatible but the yellow level as the anthers), and non-deflexed (stigmas above strain is not (Vanderplank 1991). the anthers). Because it is a widely distributed species (from For three weeks in 1994, we observed and counted Pennsylvania to Kansas and south to Texas and flower visitors at 0700, 1000, 1200, 1600, and 1900. Florida) (Vanderplank 1991), Passiflora lutea L. We noted the behavior of flower visitors and captured (Passifloraceae) provides a good test species for samples of each species for later identification. In assessing geographic variation in floral behavior. This 1997, we again observed the behavior of flower herbaceous vine produces small, greenish-yellow visitors, concentrating on the behavior of Anthemurgus flowers. Its pollination biology has been studied in passiflorae. Voucher specimens of A. passiflorae and Austin, Texas (Neff and Rozen 1995). Like other Megachile concinna were deposited in the US National Passiflora, P. lutea produces stigmas that usually Pollinating Insect Collection with the USDA Bee deflex after the flowers open; however, Neff and Biology and Systematics Laboratory at Utah State Rozen (1995) noted the styles in some flowers never University. deflex, suggesting that these flowers never receive The first test of the breeding system was done to pollen and are therefore functionally male. Using determine if Passiflora lutea normally requires a floral indirect evidence, they concluded that medium-large visitor for fruit production.