Next Article in Journal
Mangrove-Based Carbon Market Projects: 15 Considerations for Engaging and Supporting Local Communities
Next Article in Special Issue
Monitoring Diversity Profiles of Forested Landscapes in the Mediterranean Spain: Their Contribution to Local and Regional Vascular Plant Diversity
Previous Article in Journal
Impacts of El Niño–Southern Oscillation (ENSO) Events on Trophodynamic Structure and Function in Taiwan Bank Marine Ecosystem
Previous Article in Special Issue
The Diet of Eleonora’s Falcons (Falco eleonorae) during the Autumn Migration of Passerine Birds across the Aegean Sea
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Diversity
Volume 16
Issue 9
10.3390/d16090573
diversity-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Life on the Wire—Plant Growth on Power Lines in the Americas

by
Gerhard Zotz
1,2,* and
Alfredo Cascante-Marín
3
1
Functional Ecology Group, Institute of Biology and Environmental Sciences, Carl von Ossietzky Universität Oldenburg, P.O. Box 2503, D-26111 Oldenburg, Germany
2
Smithsonian Tropical Research Institute, Panama City 08343-03092, Panama
3
Centro de Investigaciones en Biodiversidad y Ecología Tropical (CIBET), Escuela de Biología, Universidad de Costa Rica, San Pedro de Montes de Oca, San José 11501-2060, Costa Rica
*
Author to whom correspondence should be addressed.
Diversity 2024, 16(9), 573; https://doi.org/10.3390/d16090573
Submission received: 12 August 2024 / Revised: 10 September 2024 / Accepted: 11 September 2024 / Published: 12 September 2024
(This article belongs to the Special Issue 2024 Feature Papers by Diversity’s Editorial Board Members)
Browse Figures
Review Reports Versions Notes

Abstract

:
There are a number of rather anecdotal reports of plant growth on power cables in the Americas, but until now there has been no systematic attempt to gauge the geographical extension of this phenomenon nor a documentation of the diversity of species found there. Using observations from the participatory science data platform iNaturalist and the scientific literature, we document almost 700 occurrences of more than 40 species of vascular plants and three lichen species on power cables with a geographical distribution over 7000 km from the southern United States to northern Argentina. Based on these observations we discuss the ecological conditions of plant growth on power cables in terms of climate; elevational distribution; and the morphological, physiological, and life history traits that allow the observed set of species to thrive on this anthropic structure.

1. Introduction

Vascular epiphytes are plants that grow on other plants, typically trees, for their entire lives, and can be distinguished from co-occurring mistletoes by their non-parasitic nature [1]. The opportunistic character of the relationship of epiphytes with their host is aptly reflected by the fact that many of them frequently establish on artificial structures that are produced by humans, such as walls, fences, or power lines. In particular, the sight of plant growth on power cables and telephone wires has fascinated biologists for decades and is a common anecdote in books about epiphytes and, in particular, epiphytic bromeliads [1,2,3,4,5] (Figure 1).
The electric companies that own the infrastructure that distributes electricity within human settlements are less enthusiastic, because a dense plant cover causes a suite of problems [6], namely it affects preventive checks for defects by maintenance teams; makes the visual inspection of conductors difficult; may cause deterioration in the aluminum conductor; reduces its lifespan, possibly caused by decreasing heat dissipation, which leads to elevated temperatures; and increases the likelihood of breakage. Bromeliads that grow on jumpers close to poles may even cause a lethal risk to humans by conducting electricity to the associated structure.
These two perspectives are also reflected in the published literature with a focus on this phenomenon. On the one hand, ecologists analyzed, e.g., the nutrient concentrations of these plants and compared them to epiphytic conspecifics on natural substrates [7] or quantified annual growth rates in the two “habitats”—tree vs. power cable [8]—while others studied plants on power cables as a component of plant biodiversity in urban settings, e.g., [9]. On the other hand, studies were initiated to quantify the occurrence of plants on power lines to document the magnitude of the perceived problem or were designed to find means to lower the rate of new colonization and to make recommendations for the removal of already-established plants [10,11]. Still, the detailed data reported in the latter studies are also interesting information for the ecologist.
There are different types of electrical network cables in the Americas. The greatest infestation occurs on bare cables, which are composed of up to 19 individual wires [10]. The resulting spaces between these wires facilitate the fixation of both the seed coma of bromeliads and the roots of growing plants. In contrast, cables covered by a thermosetting polymer compound that is resistant to weather, ultraviolet radiation, and mechanical abrasion are much less suited for attachment and, indeed, are found to be less affected [6]. When bromeliad abundance on cables and poles is high, other network structures, e.g., insulators, transformers, or consumer cables, may also be colonized.
The phenomenon of plants on power cables is currently only known from the Americas, but published reports cover a wide geographical range from the southern United States [12,13], Mexico [14], Trinidad and Tobago [15], and Panama [8] to Argentina [7] and Brazil [6,16]. Until now, there has not been any systematic attempt to gauge the geographical extension of this phenomenon in more detail nor to document the diversity of species that are found on electric cables and telephone wires.
Given the scarce data basis in the published literature, this goal could only be achieved by using information from the participatory science data platform iNaturalist [17] complemented by many observations of our own, which were also uploaded, as the main data source. The use of this platform as a research tool has been discussed in detail in several recent publications [18,19,20]; all conclude that—with appropriate quality checks—iNaturalist data meet the required standard to be useful for plant research. More specifically, we reviewed more than 100,000 observations of bromeliads and found about 700 observations of plants on electrical cables or telephone wires. The existing literature already suggested that Tillandsia recurvata would be by far the most common species, which at least partly reflects the fact that its north–south distribution is almost as extensive as that of the entire family Bromeliaceae [13]. The overall diversity of species found on these anthropic structures, however, was expected to be much larger than previously acknowledged. The current report confirms this notion: we show that more than 40 species can be found there.

2. Material and Methods

The most important source of information used in this study is iNaturalist. Specifically, we reviewed all observations of the bromeliad genera Aechmea, Billbergia, Catopsis, Glomeropitcairnia, Guzmania, Racinea, Tillandsia, Vriesea, and Werauhia that had been reported between 1 January 2014 and 31 May 2024. By far the largest number were available for the genus Tillandsia with >100,000 observations, and the lowest number were available for Glomeropitcairnia with c. 40. We also conducted searches with the keywords “power line”, “power cable”, and “línea eléctrica” in iNaturalist, none of which yielded additional observations. Although we only searched systematically for bromeliads, there were some observations in iNaturalist that referred to other taxa growing on power cables, and we also used our own observations and information from the scientific literature. This exercise resulted in 715 observations of plants on power cables and a few cases of related structures like poles and jumpers. We carefully reviewed each of these to confirm or correct the suggested species name. In the large majority of cases (630 individuals = 88% of all observations), the quality of the photograph(s), the presence of reproductive structures, and the general knowledge of geographic distributions allowed for an unambiguous species identification. For other observations, the poor quality of the pictures and the lack of reproductive structures in combination with the potential co-occurrence of species with similar morphology allowed only for the identification at the genus level, although often it was possible to narrow it down to only two possible species. These totaled 80 observations. In a third group (five cases), not even the genus could be determined with confidence.
The type of analysis then determined whether these groups were subsequently included or excluded. For example, to depict the full geographical extension of the occurrence of plants on power lines, all observations were included, while for more fine-scaled analyses at the species level, only group 1 was considered. However, to avoid duplicate observations of the same species at any location within a 1 km grid, we thinned the initial dataset using a custom script that resulted in a dataset in which there was no record of a conspecific within 1.4 km. This procedure led to the removal of 68 observations, mostly of T. recurvata.
The full dataset this report is based on (Supplementary Table S1) is the list of all 647 observations that show a plant or lichen growing on a power cable complemented with information from the literature. Only observations that are georeferenced were considered. Thus, we could visualize the geographic distribution of plant growth on power cables and analyze elevational pattern and climatic conditions. Lichens were not included in that analysis because of the scarcity of observations. Specifically, for each observation, we estimated the elevation, the annual mean temperature (MAT), and the annual precipitation (MAP) using the USGS GMTED 2010 elevation dataset (https://www.usgs.gov/coastal-changes-and-impacts/gmted2010, accessed on 7 June 2024), and the CHELSA V.1.2 climate dataset [21]. To obtain a reference of the distribution of elevation, temperature, and annual precipitation in the Americas from 35° N to 31° S (i.e., the range of latitudes of occurrences of the observations in iNaturalist), we laid a 50 km grid over the entire landmass and estimated the elevation, MAP, and MAT for each grid point. Then, we produced three histograms, which compared the distributions of elevation and climatic conditions of the Americas with those of the actual observations.
In another analysis, we assessed the occurrence of crassulacean acid metabolism (CAM) in the observed species with literature data, considering δ13C values higher (i.e., less negative) than −20‰ as an unambiguous indication of CAM [22]. For bromeliads, we used the study by Crayn et al. [23], and for orchids we used studies by Silvera et al. [24], Torres-Morales et al. [25], and Zotz and Ziegler [22] as references. There is a single observation of an unidentified species of Clusia on a power line in Trinidad. Seven species have been described for the genus for this Caribbean island [26], five of which have been tested for CAM activity; all cases were positive [26].

3. Results

The 647 observations in iNaturalist and the literature document growth on power cables of at least 44 species of vascular plants and 3 species of lichens (Table 1). A total list of observations is given in Table S1. Bromeliads were by far the most successful taxon, particularly from the genus Tillandsia, but there were also rare cases of other taxonomic groups. A particularly interesting observation was made in Trinidad. There, a large Clusia sp. shrub had established itself on a clump of bromeliads. The woody Clusia was of considerable size and mass as to visually pull down the power cable, with long dangling aerial roots. An unidentified polypody fern also emerged from the same clump, and birds had built a nest in it. There were at least two other cases of such apparent facilitation, in which plants were not directly attached to the cable, but rooted in the root mass of a larger bromeliad—one orchid of the genus Encyclia in Mexico and a Brassavola in Panama (Figure S1).
Overall, Tillandsia recurvata was by far the most abundant species. This species alone accounted for 352 (=54%) of all observations, being followed by T. capillaris with 44 records (=6%). Most of the remaining species were congenerics—more than 30 additional Tillandsia species were observed on power lines, while the genera Aechmea, Catopsis, Werauhia, and Vriesea accounted for only 1–3 species each with relatively few observations.
Geographically, observations spanned a latitudinal range of c. 7300 km from 35° N to 31° S. The longitudinal range was even larger with c. 11,000 km from 36° W to 155° W, but this was simply due to observations of one species that had been introduced to Hawaii—Tillandsia polystachia—where it has escaped from cultivation and is now found on native trees as well as on power lines.
Figure 2 visualizes the geographical distribution of the 644 observations of vascular plants on power lines in the Americas, while Figure 3 compares the elevational distribution and major climatic variables (MAT = mean annual temperature; MAP = mean annual precipitation) of the 644 growing sites with the overall elevation and climate of the Americas. The relatively low proportion of plants on power lines at lowland sites (Figure 3a) is at least partly explainable by their complete absence in Amazonia. A peak at intermediate elevations (1500–2000 m asl.; Figure 3a) coincides with relatively low temperatures (16–20 °C; Figure 3c), while a peak in the MAP of 500–1000 mm (Figure 3c) emphasizes an association with relatively dry sites.
Figure 4 shows the geographical distribution of the five species with the largest number of records. Clearly, Tillandsia recurvata was not only the most common and abundant species, but also the one with a very large geographical and elevational range—it was found from sea level to c. 4000 m asl. However, a wide geographical range is not a sufficient explanation for the success of that species, because T. usneoides has an even wider distribution, but its documented occurrence on power lines is quite limited. The other three more common species all have much more restricted distributions in general.
The vast majority of all individual plants that were found on power lines were reproducing, as evidenced by current flowers and fruits or remnants of old infructescences. Among bromeliads, 85% of all observed plants reproduced in the current or previous year, while in T. recurvata, this percentage was slightly higher with 92%. The two orchids were both non-reproductive.
The average maximum size of the bromeliad species found in this study is 70 cm based on literature data [27] (range 16–200 cm, including the inflorescence). All of the more frequent species are much smaller than this (e.g., Tillandsia recurvata at 23 cm and T. capillaris at 16 cm), and the scarcity of larger species is arguably due to mechanical problems. Such problems are suggested by several observations of the few larger individuals, whereby a large Tillandsia elongata was hanging upside down in an observation from Trinidad, and several large individuals of T. utriculata or T. polystachia were also lopsided.
The large majority of individuals and species of vascular plants found on power lines use CAM. All of the Tillandsia species, which account for almost 95% of all observations, and the single Aechmea species, use this water-conserving photosynthetic pathway. Still, CAM is not a requisite for growth on power lines, as evidenced by the remaining bromeliads of the genera Catopsis, Vriesea, and Werauhia, which are all C3. Unambiguous information of the two orchids is available for Brassavola nodosa [22], while evidence for the photosynthetic pathway of Encyclia cf. meliosma is only circumstantial—all tested species of this genus are CAM [24,25]. With the same reasoning, the unidentified Clusia found in Trinidad is also likely to use CAM [26].

4. Discussion

An astonishing number of vascular plant species occur quite frequently on power lines, and there are also a few lichens. All of the vascular plant species are typically categorized as epiphytes [28], i.e., plants that live non-parasitically on a living host. Their use of a human-made structure highlights the opportunistic nature of epiphytic growth in general. Although reproducing vigorously at this artificial growing site, the only study that investigated growth and survival on power lines, with T. flexuosa in Panama, suggests that the conditions there are more demanding than in tree crowns [8]. These demanding conditions are also reflected in the high proportion of CAM plants (Table 1).
Plants on power lines can be observed in large portions of tropical and subtropical America (Figure 2) with a conspicuous gap in Amazonia. It was instructive to compare the climatic conditions of observation sites and the total of the study area—plants on power lines are clearly disproportionately found on the drier end of the spectrum of climatic conditions of the Americas (Figure 3).
Holst [13] claimed that bromeliads are the only plants that can maintain a perch on wires. This statement clearly needs a slight correction. Our analysis shows that there are quite a few other taxa that use this artificial structure, although bromeliads, particularly Tillandsia species, are indeed by far the most common occupants. Apart from the problem of successful dispersal, the presence of orchids poses another interesting question regarding early establishment. Orchids typically need a symbiotic fungus for germination [29]. The two observations of orchids on power lines, both of which show an association with an already established bromeliad, suggest that these fungi may find suitable conditions there.
Another statement of Holst [13] needs a qualifying comment as well. Although atmospherics and, to a lesser extent, small tank-forming species of the genera Tillandsia and Catopsis indeed dominate on power cables, there are also a number of larger species like T. elongata or T. fasciculata. Particularly noteworthy is a large and reproducing individual of Werauhia sanguinolenta, observed in Golfito, Costa Rica. Circumstances were quite particular, though, because this large tank bromeliad was growing adjacent to a pole, which was probably crucially important to allow the plant to stay upright. The recurring observations of larger, tilted plants is indicative of an obvious mechanical problem of larger plants. These plants need a functional tank, and hanging upside down after losing grip is probably lethal; however, a study with Catopsis sessiliflora found that moderate tilt affects tank function relatively little [30].
The remarkable dominance of tillandsioid bromeliads begs the question whether there is a specific set of characteristics that explains the success on power lines. We suggest that it is a combination of traits from diaspores with anchoring structures, small vegetative size, pronounced drought tolerance, a breeding system characterized by autogamy or apomixis, and clonal reproduction. First, upon arrival, seeds should be able to remain attached to the cables. The characteristic plumose appendage or coma of bromeliad seeds with hooked hairs allows anchorage both in small cracks of the phorophyte bark [31] or between individual wires of power lines. The stoloniferous and hanging T. usneoides is exceptional; it mainly spreads through fragments carried by wind or birds [32]. Orchids (the most important group of epiphytes but apparently rarely found on power lines) have tiny seeds devoid of anchoring structures, which perhaps represents a critical impediment to their establishment on power lines. The same is true for the even smaller spores of epiphytic ferns.
The physical attachment to small-diameter power lines is facilitated by small size—as evidenced by Tillandsia recurvata and T. capillaris, which are often colonizing twigs [3]; however, for larger and tank-forming plants, it is a particular challenge. As stated earlier, the abovementioned observation of a large Werauhia sanguinolenta is only a seeming contradiction to this statement.
Most of the successful bromeliads on power lines are so-called atmospherics [3], i.e., small species with dense foliar trichomes that provide, e.g., photoprotection in these exposed growing sites [33], and allow for the fast uptake of water and nutrients over the entire surface of the plant [3]. Mineral nutrient acquisition from the atmosphere and rain is high, as well as of heavy metals and other chemical pollutants that also indicate the ability of some common species on power lines such as Tillandsia recurvata [11,16,34], T. capillaris [7], or T. usneoides [35] to tolerate the levels of contamination of many urban areas. Another typical feature is CAM, although this is not without exception—a number of observations show that C3 plants like Werauhia sanguinolenta or Catopsis spp. may also be able to thrive on power lines.
Data on the breeding system are only available for a handful of the species found in this study, but the limited evidence points in the direction of autogamy. Studies using genetic approaches [36], experimental pollination [37], and/or microscopy [38] reveal autogamy or cleistogamy in the two most common species (Tillandsia recurvata and T. capillaris). However, autogamy is not a strict prerequisite, since obligate outbreeders like T. aëranthos [37] and T. caput-medusae [39] are also found on power lines.
A final point is clonal reproduction. The prolific asexual production of new ramets is characteristic for the most common species. Both T. recurvata and T. capillaris were frequently forming compact aggregations of ramets around the power cables. In T. usneoides, spreading by new offshoots is by far the dominant means of reproduction, while sexual reproduction is extremely rare in that species.
How are these plants dispersed to power cables in the first place? Leal et al. [6] suggested that populations of epiphytic bromeliads from nature reserves close to urban settlements or on trees in the city itself are the initial seed source. As stated above, once established on power lines, the large majority of species seems to reproduce vigorously, allowing for the further colonization of power lines in the immediate vicinity. Frequent observations of bird nests, e.g., of Great Kiskadees (Pitangus sulphuratus) and other Tyrannidae positioned between poles and power lines (Zotz, unpubl. obs.; Figure S2), suggest another possibility. Numerous bird species use parts of or entire Tillandsia plants to build their nest and cover the bottom of their nests with Tillandsia seed down [40,41,42,43]. Thus, birds may play an active role in bringing Tillandsia plants and seeds to the immediate vicinity of power lines.
This study documented a surprising diversity of plants and a few lichens on power lines in the Americas, but we are aware of numerous caveats. We focused on bromeliads, which inevitably produced a taxonomic bias. Then, neither the used iNaturalist data nor the data from publications were collected in a systematic manner for a geographical analysis. Thus, one should be cautious when interpreting differences in the regional numbers of observations as evidence for actual differences in the frequency of plants on power cables. Moreover, the density of individuals in any given observation varied substantially, which was not quantified nor included in the analysis. Finally, we did not account for local differences in the number of active contributors to iNaturalist nor for differences in the regional density of power cables. However, we are confident that the larger picture at the continental scale (Figure 2, Figure 3 and Figure 4) is correct. Take, e.g., the big gap in occurrence in Amazonia for which we suggest two possible reasons—(1) the species that dominate on power cables, particularly Tillandsia recurvata, do not occur there, as bromeliads in general are not very common in that region [44] and (2) power lines are not very common there either.
While acknowledging the limitations of iNaturalist data to reliably detect geographic patterns, exposing the currently available data base as we do has benefits by directing future searches. For example, since it is rather unlikely that there are really no plants on power lines in Uruguay, Paraguay, or the Guyanas, this publication will hopefully motivate contributors to document observations in these countries. Moreover, overhead power lines are not only common in the Americas, but also in other regions of the world, e.g., in Japan, but we are not aware of any reports of plants or lichens using them as substrate. The occupancy of power lines is clearly not idiosyncratic to biogeographically restricted bromeliads. Thus, we hope that our paper motivates others to report cases of, e.g., more orchid or lichen species not only from the Americas, but from anywhere else on the globe. Finally, our study should also be seen as an important contribution to the growing literature on plants in urban settings [9,45,46,47]. In a world with increasing dominance of Homo sapiens, many plants take advantage opportunistically of structural resources such as fences, walls, roofs, or power lines, but the study of this phenomenon is far from complete.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/d16090573/s1, Figure S1: Brassavola nodosa, Figure S2: Nest of a Great Kiskadee; Table S1: List of observations.

Author Contributions

Conceptualization, G.Z.; methodology, G.Z. and A.C.-M.; validation, G.Z. and A.C.-M.; formal analysis, G.Z.; data curation, G.Z. and A.C.-M.; writing—original draft preparation, G.Z.; writing—review and editing, G.Z. and A.C.-M.; visualization, G.Z. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

Not applicable.

Data Availability Statement

The original contributions presented in the study are included in the article and Supplementary Materials.

Acknowledgments

We thank the many contributors to iNaturalist whose observations were the main basis of this study. Thanks also to Robert Lücking, Berlin, for the identification of Telochistes flavicans; Stefan Wester, Kaltenkirchen, for unearthing almost 20-yr-old pictures of Brassavola nodosa; and Bruce Holst, Sarasota, for adding observations to iNaturalist. Jessica Tay’s (Oldenburg), Patrick Weigelt´s, and Holger Kreft´s (both Göttingen) help with the maps is also appreciated.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Zotz, G. Plants on Plants—The Biology of Vascular Epiphytes; Springer International Publishing: Cham, Switzerland, 2016; p. 282. [Google Scholar]
  2. Benzing, D.H. Vascular Epiphytes: General Biology and Related Biota; Cambridge University Press: Cambridge, UK, 1990; p. 354. [Google Scholar]
  3. Benzing, D.H. Bromeliaceae—Profile of an Adaptive Radiation; Cambridge University Press: Cambridge, UK, 2000; p. 690. [Google Scholar]
  4. Lüttge, U. Vacular epiphytes: Setting the scene. In Vascular Plants as Epiphytes: Evolution and Ecophysiology; Lüttge, U., Ed.; Ecological Studies; Springer: Berlin/Heidelberg, Germany, 1989; Volume 76, pp. 1–14. [Google Scholar]
  5. Lüttge, U. Physiological Ecology of Tropical Plants, 2nd ed.; Springer: Berlin/Heidelberg, Germany, 2008; p. 458. [Google Scholar]
  6. Leal, L.; Santos, J.J.; Blanc, G.F.; Hack, R.O.; Piazzetta, K.D.; Lipski, B.; Lago, G.B.; Kersten, R.A.; Rodrigues, J.M. Estudos sobre ocorrência de bromélias nas redes de distribuição de energia elétrica. In Proceedings of the IX Congresso de Inovação Tecnológica em Energia Elétrica (IX CITENEL), João Pessoa, Brazil, 2–4 August 2017. [Google Scholar]
  7. Abril, A.B.; Bucher, E.H. A comparison of nutrient sources of the epiphyte Tillandsia capillaris attached to trees and cables in Cordoba, Argentina. J. Arid. Environ. 2009, 73, 393–395. [Google Scholar] [CrossRef]
  8. Wester, S.; Zotz, G. Growth and survival of Tillandsia flexuosa on electricity cables in Panama. J. Trop. Ecol. 2010, 26, 123–126. [Google Scholar] [CrossRef]
  9. Ruas, R.D.B.; de Godoy, S.M.; Feliciano, D.C.; Ruas, C.D.F.; Bered, F. A bromeliad living in the city: A case of a native species resilient to urbanization in South Brazil. Bot. J. Linn. Soc. 2024, 205, 161–176. [Google Scholar] [CrossRef]
  10. Santos, J.J.S. Estudo de Tillandsia spp. (Bromeliaceae) Epífitas Nas Redes de Distribuição de Energia Elétrica de Curitiba. Master’s Thesis, Instituto de Tecnologia para o Desenvolvimento, Curitiba, Brazil, 2014. [Google Scholar]
  11. Carvalho Blanc, G.; Lipski, B.; Santos, J.; Piazzetta, K.; Rodrigues, J.; Leal, L. Atmospheric pollutants and the occurrence of bromeliads in electric power distribution network. Int. J. Environ. Pollut. Remediat. 2018, 6, 32–40. [Google Scholar] [CrossRef]
  12. Wherry, E.T.; Capen, R.G. Mineral constituents of Spanish moss and ball moss. Ecology 1928, 9, 501–504. [Google Scholar] [CrossRef]
  13. Holst, B. Airplant aerialists on the high-wire. J. Bromel. Soc. 2019, 69, 166–170. [Google Scholar]
  14. Puente, M.-E.; Bashan, Y. The desert epiphyte Tillandsia recurvata harbours the nitrogen-fixing bacterium Pseudomonas stutzeri. Can. J. Bot. 1994, 72, 406–408. [Google Scholar] [CrossRef]
  15. Morales, J.F.; Gouda, E.; Cascante-Marín, A. New records and miscellaneous notes on the Bromeliaceae of Trinidad and Tobago. Caribb. J. Sci. 2024, 54, 18–25. [Google Scholar] [CrossRef]
  16. Piazzetta, K.D.; Ramsdorf, W.A.; Maranho, L.T. Use of airplant Tillandsia recurvata L., Bromeliaceae, as biomonitor of urban air pollution. Aerobiologia 2019, 35, 125–137. [Google Scholar] [CrossRef]
  17. iNaturalist. 2024. Available online: https://www.inaturalist.org (accessed on 25 June 2024).
  18. López-Guillén, E.; Herrera, I.; Bensid, B.; Gómez-Bellver, C.; Ibáñez, N.; Jiménez-Mejías, P.; Mairal, M.; Mena-García, L.; Nualart, N.; Utjés-Mascó, M. Strengths and challenges of using iNaturalist in plant research with focus on data quality. Diversity 2024, 16, 42. [Google Scholar] [CrossRef]
  19. Calvente, A.; da Silva, A.P.A.; Edler, D.; Carvalho, F.A.; Fantinati, M.R.; Zizka, A.; Antonelli, A. Spiny but photogenic: Amateur sightings complement herbarium specimens to reveal the bioregions of cacti. Am. J. Bot. 2023, 110, e16235. [Google Scholar] [CrossRef] [PubMed]
  20. White, E.; Soltis, P.S.; Soltis, D.E.; Guralnick, R. Quantifying error in occurrence data: Comparing the data quality of iNaturalist and digitized herbarium specimen data in flowering plant families of the southeastern United States. PLoS ONE 2023, 18, e0295298. [Google Scholar] [CrossRef]
  21. Karger, D.N.; Conrad, O.; Bhner, J.; Kawohl, T.; Kreft, H.; Soria-Auza, R.W.; Zimmermann, N.E.; Linder, H.P.; Kessler, M. Climatologies at high resolution for the earth’s land surface areas. Sci. Data 2017, 4, 170122. [Google Scholar] [CrossRef]
  22. Zotz, G.; Ziegler, H. The occurrence of crassulacean acid metabolism among vascular epiphytes from Central Panama. New Phytol. 1997, 137, 223–229. [Google Scholar] [CrossRef]
  23. Crayn, D.M.; Winter, K.; Smith, J.A.C. Multiple origins of crassulacean acid metabolism and the epiphytic habit in the Neotropical family Bromeliaceae. Proc. Natl. Acad. Sci. USA 2004, 101, 3703–3708. [Google Scholar] [CrossRef]
  24. Silvera, K.; Santiago, L.S.; Cushman, J.C.; Winter, K. The incidence of crassulacean acid metabolism in Orchidaceae derived from carbon isotope ratios: A checklist of the flora of Panama and Costa Rica. Bot. J. Linn. Soc. 2010, 163, 194–222. [Google Scholar] [CrossRef]
  25. Torres-Morales, G.; Lasso, E.; Silvera, K.; Turner, B.L.; Winter, K. Occurrence of crassulacean acid metabolism in Colombian orchids determined by leaf carbon isotope ratios. Bot. J. Linn. Soc. 2020, 193, 431–477. [Google Scholar] [CrossRef]
  26. Borland, A.M.; Griffiths, H.; Maxwell, C.; Broadmeadow, M.S.J.; Griffiths, N.M.; Barnes, J.D. On the ecophysiology of the Clusiaceae in Trinidad: Expression of CAM in Clusia minor L. during the transition from wet to dry season and characterization of three endemic species. New Phytol. 1992, 122, 349–357. [Google Scholar] [CrossRef]
  27. Smith, L.B.; Downs, R.J. Tillandsioideae (Bromeliaceae). Flora Neotrop. 1977, 14, 663–1492. [Google Scholar]
  28. Zotz, G.; Weigelt, P.; Kessler, M.; Kreft, H.; Taylor, A. EpiList 1.0—A global checklist of vascular epiphytes. Ecology 2021, 102, e03326. [Google Scholar] [CrossRef]
  29. Dressler, R.L. The Orchids: Natural History and Classification; Harvard University Press: Cambridge, UK, 1981. [Google Scholar]
  30. Zotz, G.; Laube, S. Tank function in the epiphytic bromeliad, Catopsis sessiliflora. Ecotropica 2005, 11, 63–68. [Google Scholar]
  31. Einzmann, H.J.R.; Zotz, G. Dispersal and establishment of epiphytes in human-modified landscapes. AoB Plants 2017, 9, plx052. [Google Scholar] [CrossRef] [PubMed]
  32. Billings, F.H. A study of Tillandsia usneoides. Bot. Gaz. 1904, 38, 99–121. [Google Scholar] [CrossRef]
  33. Pierce, S. The jeweled armour of Tillandsia—Multifaceted or elongated trichomes provide photoprotection. Aliso J. Syst. Florist. Bot. 2007, 23, 44–52. [Google Scholar]
  34. Schrimpff, E. Air pollution in two cities of Colombia, SA according to trace substances content of an epiphyte (Tillandsia recurvata L.). Water Air Soil Pollut. 1984, 21, 279–315. [Google Scholar] [CrossRef]
  35. Alves, E.S.; Moura, B.B.; Domingos, M. Structural analysis of Tillandsia usneoides L. exposed to air pollutants in Sao Paulo City-Brazil. Water Air Soil Poll. 2008, 189, 61–68. [Google Scholar] [CrossRef]
  36. Soltis, D.E.; Gilmartin, A.J.; Rieseberg, L.; Gardner, S. Genetic variation in the epiphytes Tillandsia ionatha and Tillandsia recurvata (Bromeliaceae). Am. J. Bot. 1987, 74, 531–537. [Google Scholar] [CrossRef]
  37. Bianchi, M.B.; Vesprini, J.L. Contrasting breeding systems in six species of Tillandsia L. (Bromeliaceae) from woody areas of Santa Fe Province: Argentina. Plant Biosyst. 2014, 148, 956–964. [Google Scholar] [CrossRef]
  38. Gilmartin, A.J.; Brown, G.K. Cleistogamy in Tillandsia capillaris (Bromeliaceae). Biotropica 1985, 17, 256–259. [Google Scholar] [CrossRef]
  39. Orozco-Ibarrola, O.A.; Flores-Hernandez, P.S.; Victoriano-Romero, E.; Corona-Lopez, A.M.; Flores-Palacios, A. Are breeding system and florivory associated with the abundance of Tillandsia species (Bromeliaceae)? Bot. J. Linn. Soc. 2015, 177, 50–65. [Google Scholar] [CrossRef]
  40. Greeney, H.F.; Zyskowski, K. A novel nest architecture within the Furnariidae: First nests of the white-browed spinetail. Condor 2008, 110, 584–588. [Google Scholar] [CrossRef]
  41. Kirwan, G.M.; Bodrati, A.; Cockle, K. The nest of the Bay-ringed Tyrannulet (Phylloscartes sylviolus), a little-known Atlantic Forest endemic, supports a close relationship between Phylloscartes and Pogonotriccus. Ornitol. Neotrop. 2010, 21, 397–408. [Google Scholar]
  42. March, W.T. Notes on the birds of Jamaica. (continued). Proc. Acad. Nat. Sci. USA 1863, 15, 283–304. [Google Scholar]
  43. Werner, S.M.; Hejl, S.J.; Brush, T. Nesting ecology of the northern beardless-tyrannulet (Camptostoma imberbe) in the lower Rio Grande Valley of Texas, USA. Ornitol. Neotrop. 2015, 26, 89–101. [Google Scholar] [CrossRef]
  44. Zizka, A.; Azevedo, J.; Leme, E.; Neves, B.; da Costa, A.F.; Caceres, D.; Zizka, G. Biogeography and conservation status of the pineapple family (Bromeliaceae). Divers. Distrib. 2020, 26, 183–195. [Google Scholar] [CrossRef]
  45. Aoki-Gonçalves, F.; Pena, J.C.; Toledo-Aceves, T.; MacGregor-Fors, I. Urban epiphytes: Bromeliad diversity in a green cover gradient across a Neotropical streetscape. Urban For. Urban Green. 2023, 83, 127901. [Google Scholar] [CrossRef]
  46. Fineschi, S.; Loreto, F. A survey of multiple interactions between plants and the urban environment. Front. For. Glob. Change 2020, 3, 30. [Google Scholar] [CrossRef]
  47. Neo, L.; Chong, K.Y.; Lindsay, S.; Middleton, D.J.; Tan, P.Y.; Er, K.B.H. A botanical oasis rather than a biological desert: Rediscoveries, new species and new records in a tropical city. Plants People Planet 2024, 6, 697–709. [Google Scholar] [CrossRef]
Diversity 16 00573 g001
Figure 1. Plants on power lines and associated structures. (a) Catopsis nutans with infructescence in the city center of Cartago (Costa Rica), (b) a large Werauhia sanguinolenta plant with infructescence, (c) immature Tillandsia balbisiana (Golfito, Costa Rica), (d) a clump of Catopsis nutans plants with dehiscing capsules releasing numerous seeds (Cartago, Costa Rica), and (e) several fruiting Tillandsia flexuosa individuals near Pedasí (Panama).
Figure 1. Plants on power lines and associated structures. (a) Catopsis nutans with infructescence in the city center of Cartago (Costa Rica), (b) a large Werauhia sanguinolenta plant with infructescence, (c) immature Tillandsia balbisiana (Golfito, Costa Rica), (d) a clump of Catopsis nutans plants with dehiscing capsules releasing numerous seeds (Cartago, Costa Rica), and (e) several fruiting Tillandsia flexuosa individuals near Pedasí (Panama).
Diversity 16 00573 g001
Diversity 16 00573 g002
Figure 2. Geographical distribution of plants and lichens on power lines in the Americas. Each dot represents one observation, although in a number of cases, dots may totally or partially overlap if there are (i) more than one species per location or (ii) conspecifics were so close that at the scale of this map a distinction is impossible. For a full list, see Table S1. An observation from Hawaii of an introduced species (Tillandsia polystachia) is not shown.
Figure 2. Geographical distribution of plants and lichens on power lines in the Americas. Each dot represents one observation, although in a number of cases, dots may totally or partially overlap if there are (i) more than one species per location or (ii) conspecifics were so close that at the scale of this map a distinction is impossible. For a full list, see Table S1. An observation from Hawaii of an introduced species (Tillandsia polystachia) is not shown.
Diversity 16 00573 g002
Diversity 16 00573 g003
Figure 3. Modeled elevations and climatic conditions of the observation sites (black bars) and the Americas in the study area of 35° N to 31° S (white bars). Plot (a) gives elevational information, plot (b) mean annual precipitation (MAP), and plot (c). annual mean temperature (MAT).
Figure 3. Modeled elevations and climatic conditions of the observation sites (black bars) and the Americas in the study area of 35° N to 31° S (white bars). Plot (a) gives elevational information, plot (b) mean annual precipitation (MAP), and plot (c). annual mean temperature (MAT).
Diversity 16 00573 g003
Diversity 16 00573 g004
Figure 4. Geographical distribution of the five most common species. Each dot represents one occurrence record. For a full list, see Table S1. (a) Tillandsia recurvata (black). (b) T. balbisiana (red), T. capillaris (orange), T. schiedeana (blue), and T. usneoides (black).
Figure 4. Geographical distribution of the five most common species. Each dot represents one occurrence record. For a full list, see Table S1. (a) Tillandsia recurvata (black). (b) T. balbisiana (red), T. capillaris (orange), T. schiedeana (blue), and T. usneoides (black).
Diversity 16 00573 g004
Table 1. List of species found growing on power lines. Given are taxon names (following World Flora Online, http://www.worldfloraonline.org, accessed on 7 May 2024, family, number of observations, and photosynthetic pathway. A full list of sources is available in Table S1. When it was not possible to identify an observation with certainty to genus or species, respectively, family names or genus names are given. Whether or not these represent additional species is impossible to tell.
Table 1. List of species found growing on power lines. Given are taxon names (following World Flora Online, http://www.worldfloraonline.org, accessed on 7 May 2024, family, number of observations, and photosynthetic pathway. A full list of sources is available in Table S1. When it was not possible to identify an observation with certainty to genus or species, respectively, family names or genus names are given. Whether or not these represent additional species is impossible to tell.
TaxonFamily# obsC3/CAM
Aechmea organensisBromeliaceae1CAM
Brassavola nodosaOrchidaceae1CAM
BromeliaceaeBromeliaceae4
Catopsis sp.Bromeliaceae2C3
Catopsis berteronianaBromeliaceae5C3
Catopsis nutansBromeliaceae5C3
Catopsis sessilifloraBromeliaceae1C3
Cladonia cf. uleanaCladoniaceae1C3
Clusia sp.Clusiaceae1CAM ?
Encyclia cf. meliosmaOrchidaceae1CAM ?
PolypodiaceaePolypodiaceae1C3
Racinaea multifloraBromeliaceae3C3
Teloschistes flavicansTeloschistaceae1C3
Tillandsia sp.Bromeliaceae43CAM ?
Tillandsia aeranthosBromeliaceae8CAM
Tillandsia balbisianaBromeliaceae28CAM
Tillandsia bandensisBromeliaceae1CAM
Tillandsia caliginosaBromeliaceae8CAM
Tillandsia capillarisBromeliaceae44CAM
Tillandsia caput-medusaeBromeliaceae7CAM
Tillandsia concolor/fasciculataBromeliaceae1CAM
Tillandsia distichaBromeliaceae3CAM
Tillandsia duratiiBromeliaceae5CAM
Tillandsia elongataBromeliaceae2CAM
Tillandsia exsertaBromeliaceae1CAM
Tillandsia fasciculataBromeliaceae9CAM
Tillandsia flexuosaBromeliaceae7CAM
Tillandsia geminifloraBromeliaceae1CAM
Tillandsia junceaBromeliaceae1CAM
Tillandsia latifolia var. divaricataBromeliaceae3CAM
Tillandsia makoyanaBromeliaceae1CAM
Tillandsia pedicellataBromeliaceae2CAM
Tillandsia pohlianaBromeliaceae1CAM
Tillandsia polystachiaBromeliaceae5CAM
Tillandsia recurvataBromeliaceae352CAM
Tillandsia recurvata/bandensisBromeliaceae1CAM
Tillandsia recurvata/capillarisBromeliaceae28CAM
Tillandsia recurvifoliaBromeliaceae1CAM
Tillandsia reichenbachiiBromeliaceae3CAM
Tillandsia schiedeanaBromeliaceae12CAM
Tillandsia schiedeana/recurvataBromeliaceae1CAM
Tillandsia stramineaBromeliaceae2CAM
Tillandsia streptocarpaBromeliaceae6CAM
Tillandsia strictaBromeliaceae3CAM
Tillandsia tehuacanaBromeliaceae1CAM
Tillandsia tenuifoliaBromeliaceae1CAM
Tillandsia tricholepisBromeliaceae3CAM
Tillandsia usneoidesBromeliaceae13CAM
Tillandsia utriculataBromeliaceae2CAM
Tillandsia virescensBromeliaceae5CAM
Tillandsia/RacinaeaBromeliaceae1CAM
Usnea cf. barbataUsneaceae1C3
Vriesea incurvataBromeliaceae1C3
Vriesea sp.Bromeliaceae1C3
Werauhia sanguinolentaBromeliaceae1C3
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Zotz, G.; Cascante-Marín, A. Life on the Wire—Plant Growth on Power Lines in the Americas. Diversity 2024, 16, 573. https://doi.org/10.3390/d16090573

AMA Style

Zotz G, Cascante-Marín A. Life on the Wire—Plant Growth on Power Lines in the Americas. Diversity. 2024; 16(9):573. https://doi.org/10.3390/d16090573

Chicago/Turabian Style

Zotz, Gerhard, and Alfredo Cascante-Marín. 2024. "Life on the Wire—Plant Growth on Power Lines in the Americas" Diversity 16, no. 9: 573. https://doi.org/10.3390/d16090573

APA Style

Zotz, G., & Cascante-Marín, A. (2024). Life on the Wire—Plant Growth on Power Lines in the Americas. Diversity, 16(9), 573. https://doi.org/10.3390/d16090573

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop