30 Halcomb, M. and S. Reed. 2012. Hydrangea production. Univ. of Tennessee Extension Publication.
31 Hempel, P., A. Hohe, and C. Tränkner. 2018. Molecular reconstruction of an old pedigree of diploid and triploid Hydrangea macrophylla genotypes. Front. Plant Sci. 9:1–13. doi:10.3389/fpls.2018.00429.
32 Hokanson, S.C. and S. McNamara. 2013. Can’t always get what we want! Finding and creating cold hardiness for screening at the University of Minnesota. Acta Hortic. 900:193–202.
33 Hollick, A. 1925. A new fossil species of Hydrangea. J. Torrey Bot. Soc. 52:21–22.
34 Hufford, L. 1995. Seed morphology of Hydrangeaceae and its phylogenetic implications. Int. J. Plant Sci. 156:555–580.
35 Hufford, L., M.L. Moody, and D.E. Soltis. 2001. A phylogenetic analysis of Hydrangeaceae based on sequences of the plastid gene matk and their combination with rbcL and morphological data. Int. J. Plant Sci. 162:835–846.
36 Hurme, P., T. Repo, O. Savolainen, and T. Pääkkönen. 1997. Climatic adaptation of bud set and frost hardiness in Scots pine (Pinus sylvestris). Can. J. For. Res. 27:716–723. doi:10.1139/cjfr‐27‐5‐716.
37 Ishimaru, K., K. Ono, T. Kashiwagi. 2004. Identification of a new gene controlling plant height in rice using the candidate‐gene strategy. Planta 218:388–395.
38 Ito, T., S. Kaneko, M. Yokogawa, G. Song, H. Choi, and Y. Isagi. 2013. Isolation and characterization of microsatellite markers for Hydrangea luteovenosa (Hydrangeaceae), an endangered species in Korea. Kor. J. Plant Taxon. 43:30–33. doi:10.11110/kjpt.2013.43.1.30.
39 Jacobs, S.J. 2010. Flag flower morphology and phylogeny of Hydrangeaceae tribe Hydrangeeae. Master’s Thesis, Washington State Univ.
40 Jones, K.D., S.M. Reed, and T.A. Rinehart. 2007. Analysis of ploidy level and its effects on guard cell length, pollen diameter, and fertility in Hydrangea macrophylla. HortScience 42:483–488.
41 Joung, Y.H., J.K. Suh, N.S. Lee, S.M. Eum, I.‐Y.Choi, and M.S. Roh. 2010. Identification of Hydrangeaceae accessions of wild origin from Jeju, Korea, using molecular markers. Plant Genet. Resourc. 8:235–241. doi:10.1017/S1479262110000286.
42 Kanno, H. and K. Seiwa. 2004. Sexual vs. vegetative reproduction in relation to forest dynamics in the understory shrub, Hydrangea paniculata (Saxifragaceae). Plant Ecol. 170:43–53. doi:10.1023/B:VEGE.0000019027.88318.54.
43 Kästner, U., E. Klocke, and S. Abel. 2017. Regeneration of protoplasts after somatic hybridization of Hydrangea. Plant Cell Tissue Organ Cult. 129:359–373. doi:10.1007/s11240‐017‐1183‐x.
44 Kitamura, Y., M. Hosokawa, C. Tanaka, and S. Yazawa. 2008. Identification and sterilization of epiphytic bacterial flora near hydrangea shoot apical meristems. J. Jap. Soc. Hortic. Sci. 77:418–425. doi:10.2503/Jjshs1.77.418.
45 Kostel‐Hughes, F., T.P. Young, and J.D. Wehr. 2005. Effects of leaf litter depth on the emergence and seedling growth of deciduous forest tree species in relation to seed size. J. Torrey Bot. Soc. 132:50–61. doi:10.3159/10955674(2005)132[50:EOLLDO]2.0.CO;2.
46 Kudo, N. and Y. Niimi. 1999. Production of interspecific hybrids between Hydrangea macrophylla f. hortensia (Lam.) Rehd. and H. arborescens L. J. Jap. Soc. Hortic. Sci. 68:428–439. doi:10.1248/cpb.37.3229.
47 Lawson‐Hall, T. and B. Rothera. 1995. Hydrangeas, a gardeners’ guide. Timber Press, Portland, OR.
48 Ledbetter, D.I. and J.E. Preece. 2004. Thidiazuron stimulates adventitious shoot production from Hydrangea quercifolia Bartr. leaf explants. Scientia Hortic. 101:121–126. doi:10.1016/j.scienta.2003.09.014.
49 Linnaeus, C. 1753. Species plantarum: exhibentes plantas rite cognitas, ad genera relatas, cum differentiis specificis, nominibus trivialibus, synonymis selectis, locis natalibus, secundum systema sexuale digestas. Impensis Laurentii Salvii, Stockholm.
50 Long, C. and R. Li. 2004. Ethnobotanical studies on medicinal plants used by the red‐headed Yao People in Jinping, Yunnan Province, China. J. Ethnopharmacol. 90:389–395.
51 Mallet, C., R. Mallet, and H. van Trier. 1992. Hydrangeas: Species and cultivars. Center d’Art Floral, Varengeville, France.
52 Manchester, S.R. 1994. Fruits and seeds of the middle Eocene nut beds flora, Clarno Formation, Oregon. Palaeontogr. Amer. 58:1–205.
53 McClintock, E. 1957. A monograph of the genus Hydrangea. Proc. Calif. Acad. Sci. XXIX:147–256. doi:10.1016/S0079‐8169(08)61510‐X.
54 McNamara, S. and S.C. Hokanson. 2010. Cold hardiness of weigela (Weigela florida Bunge) cultivars. J. Environ. Hortic. 28:35–40.
55 Miller, J.F. and J.J. Hammond. 1991. Inheritance of reduced height in sunflower. Euphytica 53:131–136.
56 Mmbaga, M.T., M.‐S. Kim, L. MacKasmiel, and N.B. Klopfenstein. 2015. Differentiation of Corynespora cassiicola and Cercospora sp. in leaf‐spot diseases of Hydrangea macrophylla using a PCR‐mediated method. Can. J. Plant Sci. 95:711–717. doi:10.4141/cjps‐2014‐354.
57 Mmbaga, M.T., M.S. Kim, L. MacKasmiel, and Y. Li. 2012. Evaluation of Hydrangea macrophylla for resistance to leaf‐spot diseases. J. Phytopathol. 160:88–97. doi:10.1111/j.1439‐0434.2011.01862.x.
58 Mmbaga, M.T. and J.B. Oliver. 2007. Effect of biopesticides on foliar diseases and Japanese beetle (Popillia japonica) adults in roses (Rosa spp.), oakleaf hydrangea (Hydrangea quercifolia), and crapemyrtle (Lagerstroemia indica). Arboric. Urban For. 33:210–219.
59 Morgan, D.R. and D.E. Soltis. 1993. Phylogenetic relationships among members of Saxifragaceae sensu lato based on rbcL sequence data. Ann. Mo. Bot. Gard. 80:631. doi:10.2307/2399851.
60 Mortreau, E., H. Bertrand, C. Lambert, and J. Lallemand. 2003. Collection of Hydrangea: genetic resources characterization. Acta Hortic. 623:231–238. doi:10.17660/ActaHortic.2003.623.25.
61 Mortreau, E., S. Siljak‐Yakovlev, M. Cerbah, S.C. Brown, H. Bertrand, and C. Lambert. 2010. Cytogenetic characterization of Hydrangea involucrata Sieb. and H. aspera D. Don complex (Hydrangeaceae): Genetic, evolutional, and taxonomic implications. Tree Genet. Genomes 6:137–148. doi:10.1007/s11295‐009‐0235‐8.
62 Niklas, K.J. and R.M. Brown. 1981. Ultrastructural and paleobiochemical correlations among fossil leaf tissues from the St. Maries River (Clarkia) area, northern Idaho, USA. Am. J. Bot. 68:332–341.
63 Pagter, M., J.F. Hausman, and R. Arora. 2011a. Deacclimation kinetics and carbohydrate changes in stem tissues of Hydrangea in response to an experimental warm spell. Plant Sci. 180:140–148. doi:10.1016/j.plantsci.2010.07.009.
64 Pagter, M., C.R. Jensen, K.K. Petersen, F. Liu, and R. Arora. 2008a. Changes in carbohydrates, ABA and bark proteins during seasonal cold acclimation and deacclimation in Hydrangea species differing in cold hardiness. Physiol. Plant. 134:473–485. doi:10.1111/j.1399‐3054.2008.01154.x.
65 Pagter, M., A. Kristoffersen, P. Brønnum, and M. Jensen. 2010. Phenotypic differences in development of cold hardiness in three latitudinal populations of Acer platanoides L. Scand. J. For. Res. 25:412–420.
66 Pagter, M., I. Lefèvre, R. Arora, and J.F. Hausman. 2011b. Quantitative and qualitative changes in carbohydrates associated with spring deacclimation in contrasting Hydrangea species. Environ. Exp. Bot. 72:358–367. doi:10.1016/j.envexpbot.2011.02.019.
67 Pagter, M., F. Liu, C.R. Jensen, and K.K. Petersen. 2008b. Effects of chilling temperatures and short photoperiod on PSII function, sugar concentrations and xylem sap ABA concentrations in two Hydrangea species. Plant Sci. 175:547–555. doi:10.1016/j.plantsci.2008.06.006.
68 Pagter, M., K. Sergeant, S.M. Møller, H.C. Bertram, and J. Renaut. 2014. Changes in the proteome and water state in bark and xylem of Hydrangea paniculata during loss of freezing tolerance. Environ. Exp. Bot. 106:99–111. doi:10.1016/j.envexpbot.2013.11.009.
69 Pagter, M. and M. Williams. 2011. Frost dehardening and rehardening of Hydrangea macrophylla stems and buds. HortScience