There is increased interest in using native shrubs for landscaping to support pollinators (Gagliardi and Brand, 2007; Tallamy, 2007). Nurseries producing landscape plants typically grow cultivars, which are selections with better performance and ornamental characteristics than is typical of straight species (Wilde et al., 2015). Native shrubs produced from seeds are less marketable to a broad base of consumers because of variable quality (Getz, 2015). Straight species of native shrubs are frequently less suitable for landscaping because many are naturally large in stature and consumers desire native shrubs that will fit their landscape and also support pollinators (Hansen, 2017). For this reason, nursery growers prefer to produce cultivars of native shrubs that maintain a compact habit. Native shrub cultivars have also been selected for having unique flower or foliage coloration or form compared with the straight species.
Some consumer and conservation groups claim that native plant cultivars (nativars) are less frequently visited by pollinators than the straight species and are, thus, less useful for developing pollinator plantings (Hansen, 2017). A limited number of studies have compared pollinator visitation for native herbaceous perennials and their cultivars. White (2016) evaluated insect visitation for 11 different native herbaceous perennial species and a single cultivar of each species. Similarly, Poythress and Affolter (2018) evaluated three native herbaceous perennial species and one native grass species and a single cultivar of each species. Nevison (2016) compared insect visitation for native Phlox paniculata and six of its cultivars. We could locate no published scientific studies comparing pollinator visitation for native shrub species and their cultivars. Baisden et al. (2018) evaluated caterpillar feeding damage for 10 native woody plant species and 18 cultivars selected for six different desirable traits. We evaluated insect pollinator visitation for six native shrub species and one or more cultivars of each species, which were selected for traits, including compact habit, foliage color, flower color, or flower form. The objectives of this research were to determine if cultivars attracted the same number of insects as their species and to observe the diversity and quantity of different groups of insects.
Baisden, E.C., Tallamy, D.W., Narango, D.L. & Boyle, E. 2018 Do cultivars of native plants support insect herbivores? HortTechnology 28 596 606
Comba, L., Corbet, S.A., Barron, A., Bird, A., Collinge, S., Miyazaki, N. & Powell, M. 1999 Garden flowers: Insect visits and the floral reward of horticulturally-modifed variants Ann. Bot. 83 73 86
Denisow, B., Antoń, S. & Zymczak, G. 2013 The flowering, pollen production, and insect visitors in the ornamental shrub Potentilla fruticosa L. (Rosaceae) J. Apic. Sci. 57 95 106
Dirr, M.A. 2009 Manual of woody landscape plants. 6th ed. Stipes Publishing, Champaign, IL
Gagliardi, J.A. & Brand, M.H. 2007 Connecticut nursery and landscape industry preferences for solutions to the sale and use of invasive plants HortTechnology 17 39 45
Garbuzov, M. & Ratnieks, F.L. 2014 Quantifying variation among garden plants in attractiveness to bees and other flower-visiting insects Funct. Ecol. 28 364 374
Getz, L. 2015 Landscape design goes native. Turf Mag. 12 June 2019. <https://www.turfmagazine.com/landscape-designbuildinstallation/landscape-design-goes-native/>.
Gillespie, S.D., Bayley, J. & Elle, E. 2017 Native bumble bee (Hymenoptera: Apidae) pollinators vary in floral resource use across an invasion gradient Can. Entomol. 149 204 213
Gottsberger, G. 1977 Some aspects of beetle pollination in the evolution of flowering plants, p. 211–226. In: K. Kubitzki (ed.). Flowering plants. Plant systematics and evolution/Entwicklungsgeschichte und Systematik der Pflanzen. vol. 1. Springer, Vienna, Austria
Goulson, D. & Darvill, B. 2004 Niche overlap and diet breadth in bumblebees; are rare species more specialized in their choice of flowers? Apidologie 35 55 63
Goulson, D. 2003 Bumblebees: Behaviour, ecology, and conservation. Oxford Univ. Press, New York, NY
Gumbert, A. 2000 Color choices by bumble bee (Bombus terrestris): Innate preferences and generalization after learning Behav. Ecol. Sociobiol. 48 36 43
Hansen, J. 2017 Natives vs. nativars: The need for both. Nursery Mgt. 12 June 2019. <https://www.turfmagazine.com/landscape-designbuildinstallation/landscape-design-goes-native/>.
Heinrich, B. 1979 Bumblebee economics. Harvard Univ. Press, Cambridge, MA
Hemingson, J.C. 1986 The pollination biology of Clethra alnifolia L. (Clethraceae). Univ. of Connecticut, Storrs, CT, MS Thesis
Hightshoe, G.L. 1988 Native trees shrubs, and vines for urban and rural America. Wiley, New York, NY
Lenz, L.M. 1997 Plant 9,874 Potentilla fruticosa plant named ‘Pink Beauty’. 17 June 2019. <https://patents.google.com/patent/USPP9874P/en>.
Mach, B.M. & Potter, D.A. 2018 Quantifying bee assemblages and attractiveness of flowering woody landscape plants for urban pollinator conservation PLoS One 13 e0208428
Miller, M.D. 2002 Shrubby potentilla. Royal Hort. Soc. 8 Nov. 2018. <http://staging.rhs.org.uk/plants/pdfs/plant-trials-and-awards/plant-bulletins/potentilla.pdf>.
Nevison, K.A. 2016 Considering a role for native plant cultivars in ecological landscaping: And experiment evaluating insect preferences and nectar forage values of Phlox species vs. its cultivars. Univ. of Delaware, Newark, DE, MS Thesis
Ollerton, J., Alarcón, R., Waser, N.M., Price, M.V., Watts, S., Cranmer, L., Hingston, A., Peter, C.I. & Rotenberry, J. 2009 A global test of the pollination syndrome hypothesis Ann. Bot. 103 1471 1480
Poythress, J.C. & Affolter, J.M. 2018 Ecological value of native plant cultivars versus wild-type native plants for promoting hemiptera diversity in suburban areas Environ. Entomol. 74 890 901
Real, L.A. & Rathcke, B.J. 1991 Individual variation in nectar production and its effect on fitness in Kalmia latifolia Ecology 72 149 155
Sajjad, A. & Saeed, S. 2010 Floral host plant range of syrphid flies (Syrphidae: Diptera) under natural conditions in southern Punjab, Pakistan Pak. J. Bot. 42 1187 1200
Segraves, K.A. & Thompson, J.N. 1999 Plant polyploidy and pollination: Floral traits and insect visits to diploid and tetraploid Heuchera grossulariifolia Evol. 53 1114 1127
Shi, J., Luo, Y.B., Bernhardt, P., Ran, J.C., Liu, Z.J. & Zhou, Q. 2009 Pollination by deceit in Paphiopedilum barbigerum (Orchidaceae): A staminode exploits the innate colour preferences of hoverflies (Syrphidae) Plant Biol. 11 17 28
Tallamy, D. 2007 Bringing nature home. Timber Press, Portland, ME
Tuell, J.K., Fiedler, A.K., Landis, D. & Isaacs, R. 2008 Visitation by wild and managed bees (Hymenoptera: Apoidea) to eastern US native plants for use in conservation programs Environ. Entomol. 37 707 718
Waser, N.M., Chittka, L., Price, M.V., Williams, N.M. & Ollerton, J. 1996 Generalization in pollination systems, and why it matters Ecology 77 1043 1060
White, A. 2016 From nursery to nature: Evaluating native herbaceous flowering plants versus native cultivars for pollinator habitat restoration. Univ. of Vermont, Burlington, VT, MS Thesis
Wilde, H.D., Gandhi, K.J.K. & Colson, G. 2015 State of the science and challenges of breeding landscape plants with ecological function Hort. Res. 69 1 8
Wilson, J.S. & Carril, O.J.M. 2015 The bees in your backyard: A guide to North America’s bees. Princeton Univ. Press, Princeton, NJ