Clarifying Taxonomy and Nomenclature of Fothergilla (Hamamelidaceae) Cultivars and Hybrids

Abstract

<jats:p> <jats:italic>Fothergilla</jats:italic> L. spp. are valuable nursery and garden plants. However, clear differentiation among <jats:italic>F. gardenii</jats:italic> Murray, <jats:italic>F. major</jats:italic> Lodd., and potential hybrids can be difficult based solely on morphological characteristics. The objectives of this work were to verify and describe the existence of interspecific hybrids and to clarify the proper nomenclature for cultivars of <jats:italic>Fothergilla</jats:italic> that are commonly grown in the nursery industry. A comparison of morphological characteristics was made among diverse clones representing both species and potential hybrids. A combination of chromosome counts and DNA contents was used to clearly differentiate among <jats:italic>F. gardenii</jats:italic> (<jats:italic>2n</jats:italic> = 4<jats:italic>x</jats:italic> = 48), <jats:italic>F. major</jats:italic> (<jats:italic>2n</jats:italic> = 6<jats:italic>x</jats:italic> = 72), and hybrids (<jats:italic>2n</jats:italic> = 5<jats:italic>x</jats:italic> = 60). It was determined that the majority of cultivars represented in commerce were hybrids. <jats:italic>Fothergilla</jats:italic> ×<jats:italic>intermedia</jats:italic> Ranney and Fantz (hybrid fothergilla) is proposed as the name for these hybrids and is validated with a Latin diagnosis. Although certain morphological characteristics can be used to differentiate between <jats:italic>F. gardenii</jats:italic> and <jats:italic>F. major</jats:italic>, the hybrids tend to be intermediate and are particularly difficult to separate from <jats:italic>F. major</jats:italic> on the basis of appearance. The correct classification and nomenclature for 17 different taxa are presented.</jats:p>

Development of microsatellites from Fothergilla ×intermedia (Hamamelidaceae) and cross transfer to four other genera within Hamamelidaceae

“…We used a conservative 2-bp allelic category size determination standard error range for reproducibility and the 2-bp resolution of the QIAxcel Capillary Electrophoresis System. Ploidy level varies from 4 x to 6 x in Fothergilla ( Ranney et al, 2007 ) and 2 x to 6 x in Corylopsis as compared to the diploid Parrotia and Hamamelis species ( Zhang et al, 2003 ). Due to ploidy variation, each allele was scored as either 0 (absent) or 1 (present), and nonamplified loci were scored as missing data.…”

Phylogenomics of polyploid Fothergilla (Hamamelidaceae) by RAD‐tag based GBS—insights into species origin and effects of software pipelines

“…These F 1 4 x plants then backcrossed/interbred with the larger pool of 4 x F. gardenii . (ii) The 6 x and 4 x plants could have hybridized to create F 1 5 x plants as has been documented in garden settings (Ranney et al, ). Although pentaploids typically have low fertility, they can potentially serve as a reproductive bridge and have been reported to produce occasional 2 x gametes in other genera (Vorsa et al, ).…”

“…Holoploid, 2C genome size (i.e., DNA content of entire non‐replicated chromosome complement irrespective of ploidy) was calculated based on an internal standard of a known genome size ( Pisum sativum L. ‘Ctirad’, 2C DNA = 8.76 pg; Greilhuber et al, ). Ploidy levels were determined based on published relationships between genome sizes and ploidy levels for Fothergilla (Ranney et al, ).…”

“…Although these two species have allopatric native ranges, they have been grown together in cultivation and will freely hybridize. A recent cytological survey (Ranney et al, ) found that the majority of cultivars represented in commerce were pentaploid hybrids with (2 n = 5 x = 60) and a nothospecies F . × intermedia Ranney & Fantz was proposed as the hybrid designation.…”

Genome Sizes, Ploidy Levels, and Base Compositions of Styrax Species and Cultivars

“…Genome size is a taxonomically significant character that can vary both intraspecifically and intragenerically (Contreras and Shearer, 2018;Greilhuber, 1998;Ranney et al, 2007;Shearer and Ranney, 2013). Intraspecific variation can be due to reproductive isolation of populations, chromosomal variation, and heterochromatin polymorphisms (Greilhuber 1998).…”