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ASHS 2024 Annual Conference

 

‘Lilac Marble’: A New Hybrid Cultivar of Magnolia

Authors:
Wenqian Zhang College of Landscape Architecture, Central South University of Forestry & Technology, Changsha, Hunan 410004, China; and Hunan Big Data Engineering Technology Research Center of Natural Protected Areas Landscape Resources, Changsha, Hunan 410004, China

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Zachary J. Hutzell Department of Horticulture, University of Georgia, Athens, GA 30602, USA

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Donglin Zhang Department of Horticulture, University of Georgia, Athens, GA 30602, USA

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Xiaoling Jin College of Landscape Architecture, Central South University of Forestry & Technology, Changsha, Hunan 410004, China; and Hunan Big Data Engineering Technology Research Center of Natural Protected Areas Landscape Resources, Changsha, Hunan 410004, China

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Qiulin Liao College of Landscape Architecture, Central South University of Forestry & Technology, Changsha, Hunan 410004, China; and Hunan Big Data Engineering Technology Research Center of Natural Protected Areas Landscape Resources, Changsha, Hunan 410004, China

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Magnolia figo (Lour.) DC. var. crassipes (Law) Figlar & Noot. is a captivating, purple-flowered plant of the Magnoliaceae family (Magnolia). It is a small tree or shrub up to 2 to 5 m in height. Indigenous to China, M. figo var. crassipes holds a significant position as a parental contributor in controlled crosses within the Magnoliaceae lineage. This acclaim arises from its strikingly deep-purple hue and the entrancing fragrance exuded by its blossoms.

Magnolia figo is a native to the southern provinces of China. This evergreen shrub maintains a stature of 2 to 3 m and has garnered popularity for its aromatic blooms. Notably, both M. figo var. crassipes and M. figo exhibit considerable potential in terms of development and use as ornamental trees. Their intrinsic value finds expression in horticulture, garden design, and urban landscapes, as elaborated by Chai et al. (2018).

China stands as the global epicenter for an abundant array of Magnolia plant species, solidifying its status as the preeminent “Kingdom of Magnolia” (Dirr 2010). Harnessing the remarkable ornamental qualities inherent in Magnolia, horticulturists have embarked on a journey of hybrid breeding, yielding a rich tapestry of novel cultivars. Among these, noteworthy introductions include ‘Yunrui’ (Xu et al. 2014), ‘Mengyuan’ (Shao et al. 2015), and ‘Mengxing’ (Shao et al. 2016). The flowers of these cultivars are one solid color. Through their dedicated efforts, the Magnolia breeding program at the Central South University of Forestry and Technology and the University of Georgia (UGA) proudly unveiled the enchanting ‘Lilac Marble’ cultivar with patterned flowers.

The pivotal aim of our study was to engage in the hybridization, validation, and comprehensive characterization of the offspring derived from the crossbreeding of M. figo var. crassipes and M. figo. By integrating the captivating purple flower into new cultivars, the resultant hybrids stand to enhance the aesthetic and practical value of Magnolia species, gracing landscapes with a spectrum of vibrant colors.

Origin

During Spring 2016, Yixia Chai conducted a controlled cross between M. figo var. crassipes and M. figo. This crossbreeding initiative took place at the experimental field of the Forestry Department in Hunan Province (lat. 28°6′56.32″N, long. 113°2′45.89″E; elevation, 112 m). The successful outcome yielded 68 seeds through 12 cross-pollination events. Spring 2017 marked the commencement of seed germination, culminating in the selection and subsequent transplanting of 48 promising seedlings to the Horticulture Farm at the University of Georgia (Athens, GA, USA).

Over a span of 6 years, observations were carried out, leading to the identification of a seedling boasting light-pink tepals that were elegantly shaded with lilac marbling, and was aptly christened ‘Lilac Marble’ (Fig. 1B and C). Flowers generated through stem-cutting propagation consistently mirrored the coloration of the original selected specimen, providing strong evidence of ‘Lilac Marble’ trait inheritance.

Fig. 1.
Fig. 1.

Habit and blossom of the hybrid cultivar of Magnolia ‘Lilac Marble’. (A) Oval growth habit and loaded flowers. (B) Full, open flower. (C) Outer and inner tepals. (D) Stamens.

Citation: HortScience 58, 12; 10.21273/HORTSCI17414-23

Continuing through the years 2017–23, the liners consistently exhibited a stable and unwavering phenotype. These specimens displayed robust growth patterns, showcased commendable adaptability, and, remarkably, resisted the impact of significant diseases and pests, thus fortifying their promising potential.

Description

The distinguishing ornamental traits of ‘Lilac Marble’ encompass an oval canopy adorned with lustrous foliage. These leaves provide an inviting contrast to the profusion of blooms, which manifest as delicately hued light-pink–purple flowers measuring ∼4.5 cm in diameter. The flowers boast a shallow, cup-shaped corolla (Fig. 1B), thus contributing to their visual allure.

Furthermore, its evergreen nature enhances its appeal. The glossy foliage that graces ‘Lilac Marble’ remains captivating and attractive throughout both the warmth of summer and the cool of winter. The specific characteristics that set ‘Lilac Marble’ apart are delineated as follows.

Habit.

‘Lilac Marble’ embodies the enduring charm of a small, evergreen tree or shrub, showcasing a distinctive V-shaped growth pattern (Fig. 1A). This cultivar attained a height of 3.5 m and spanned 2.9 × 3.2 m in width by year 7 at the UGA Horticultural Farm, revealing an appealingly well-formed oval canopy. The branches feature a fetching reddish brown hue (Supplemental Fig. 1A).

Foliage.

The leaves of ‘Lilac Marble’ exude a leathery texture and a glossy sheen, retaining these appealing attributes both in the summer and winter. Upon emergence, the new leaves present themselves in a charming yellow-green hue (Supplemental Fig. 1B), which gracefully matures into a medium-green shade (Supplemental Fig. 1D). Characterized by blades featuring an apex that ranges from acute to acuminate, these leaves measure between 8.5 and 12.5 cm in length, and 1.6 to 4.3 cm in width. This translates into a length-to-width ratio of 2.5.

The petioles are abbreviated and sturdy at 5 to 7 mm in length, whereas the stipules are embellished with rings measuring 3 to 4 mm (Supplemental Fig. 1F and G). The shoots and leaf buds present a delightful covering of gray-orange fluffy hairs, contributing to the plant’s distinctive visual appeal.

Flower.

‘Lilac Marble’ showcases an abundant profusion of flowers, almost one flower per node. Within each floral assembly, two bracts are densely covered with reddish brown sericeous hairs. The individual blossoms feature a corolla composed of three to six tepals, collectively forming a shallow cup-shaped structure (Table 1, Fig. 1B). The period of bloom extends from early spring, commencing around 26 March and gracefully fading by 19 May (US Department of Agriculture Cold Hardiness Zone 8a).

Table 1.

Distinguishing foliage and flower characteristics of Magnolia figo var. crassipes (female) and Magnolia figo (male), along with their hybrid ‘Lilac Marble’.

Table 1.

The outer tepals, with an obovate elliptic form, measure between 4.3 and 4.5 cm in length and 1.3 to 1.6 cm in width. In contrast, the inner tepals adopt a narrow ovate-lanceolate shape, spanning from 3.5 to 3.7 cm in length and 0.9 to 1.0 cm in width. The outer side of the tepals is characterized by a light-purple hue [Purple-Violet Group, Royal Horticultural Society (RHS) N80A] whereas the middle zone of the inner side showcases a very pale-purple tint (Red-Purple Group, RHS 67C), and the basal area of the inner side takes on a yellowish white shade (White Group, RHS NN155D) (Fig. 1C). The tepals themselves display a red-purple coloration (Royal Horticultural Society 2015).

Noteworthy features include stamen scars, usually measuring 2 to 3 mm in length, that are purple (RHS N78A). The gynoecium is situated above the androecium, and assumes a cylindrical form that measures 6 to 10 mm. In addition, the gynophore attains a length of 2 to 3 mm, whereas the ovary exhibits a green coloration (RHS 134B).

Fruit.

The cross between M. figo var. crassipes and M. figo yielded improved seed quality and a greater germination rate (data not presented). However, no fruit (seed) of this selected seedling have been observed. In all instances, the ovaries have aborted.

Additional note.

The cold hardiness of ‘Lilac Marble’ proves to be robust, as it withstood temperatures as low as –15 °C last winter in Georgia, USA, without sustaining any damage. The phenology of this cultivar is significantly influenced by weather conditions (blossoming could occur 2–3 weeks earlier or later), underscoring the pivotal role played by climate in its growth and development.

Propagation

The successful propagation of ‘Lilac Marble’ can be achieved by rooting semihardwood terminal stem cuttings collected during June or July, using Hormodin #3 (OHP, Inc., Mainland, PA). Over the past five years, the rooting success rate has ranged from 36.4% to 75% (Zou et al. 2022). These rooted cuttings can be transplanted into 1-gal round pots (volume, 2.8 L) after 4 months. Proper mist control is crucial during this process. Initially, misting should occur for 10 s every 10 min during the first 2 weeks, subsequently transitioning to 10 s every 20 min for the subsequent 2 to 4 weeks. After root initiation has taken place, misting should be adjusted to 10 s every 30 or 60 min to prevent the onset of root rot. It is advisable to provide extended periods of light (from 4 pm to 10 pm) to stimulate new growth before the onset of overwintering. This practice contributes significantly to the overall health and development of the plant.

For optimal care, these newly developed cultivar liners should undergo overwintering within a heated greenhouse, maintaining a minimum temperature of 3 to 5 °C. When cultivating potted plants, a warm and humid environment with a temperature range of 20 to 38 °C is ideal. Remarkably, this plant demonstrates resilience, tolerating temperatures as high as 40 °C during summer and as low as –15 °C in winter. Providing either full sun or partial shade is preferable for fostering robust liner growth. When selecting planting sites, opt for locations characterized by deep, well-drained, and slightly acidic soil. For container production, the use of a pine bark–based medium is recommended. Augment the growth of liners with slow-release fertilizer (14–4–14, 8–9 months) at a rate of 1 tsp/gal pot, ensuring the plant’s nutritional needs are well met.

Availability

Please note that ‘Lilac Marble’ is currently available for restricted test agreement exclusively. Data and photographs were acquired at the UGA Horticulture Farm in Watkinsville, GA, USA.

References Cited

  • Chai YX, Hu XJ, Zhang DL, Liu XL, Liu CX, Jun XL. 2018. Studies on compatibility of interspecific hybridization between Michelia crassipes and M. figo, M. maudiae, M. platypetala. Yuan Yi Xue Bao. 45(10):19701978. https://doi.org/10.16420/j.issn.0513353x.2017-0779.

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  • Dirr MA. 2010. Manual of woody landscape plants (6th ed). Stipes Publishing, Champaign, IL, USA.

  • Royal Horticultural Society. 2015. RHS colour chart (6th ed). Royal Horticultural Society, London, UK.

  • Shao WH, Jiang JM, Dong RX. 2015. A new Michelia cultivar ‘Mengyuan’. Linye Kexue. 51(10):155. https://doi.org/10.11707/j.1001-7488.20151021.

    • Search Google Scholar
    • Export Citation
  • Shao WH, Jiang JM, Dong RX. 2016. A new Michelia cultivar ‘Mengxing’. Yuan Yi Xue Bao. 43(6):12191220. https://doi.org/10.16420/j.issn.0513-353x.2015-0888.

    • Search Google Scholar
    • Export Citation
  • Xu HY, Li WX, Pan YZ, Gong X. 2014. A new Michelia cultivar ‘Yunrui’. Yuan Yi Xue Bao. 41(2):403404. https://doi.org/10.16420/j.issn.0513-353x.2014.02.021.

    • Search Google Scholar
    • Export Citation
  • Zou YP, Zhang DL, Hutzell Z. 2022. Windows of opportunity for rooting woody stem cuttings. Proceedings of IPPS. 72:207214.

  • Fig. 1.

    Habit and blossom of the hybrid cultivar of Magnolia ‘Lilac Marble’. (A) Oval growth habit and loaded flowers. (B) Full, open flower. (C) Outer and inner tepals. (D) Stamens.

  • Chai YX, Hu XJ, Zhang DL, Liu XL, Liu CX, Jun XL. 2018. Studies on compatibility of interspecific hybridization between Michelia crassipes and M. figo, M. maudiae, M. platypetala. Yuan Yi Xue Bao. 45(10):19701978. https://doi.org/10.16420/j.issn.0513353x.2017-0779.

    • Search Google Scholar
    • Export Citation
  • Dirr MA. 2010. Manual of woody landscape plants (6th ed). Stipes Publishing, Champaign, IL, USA.

  • Royal Horticultural Society. 2015. RHS colour chart (6th ed). Royal Horticultural Society, London, UK.

  • Shao WH, Jiang JM, Dong RX. 2015. A new Michelia cultivar ‘Mengyuan’. Linye Kexue. 51(10):155. https://doi.org/10.11707/j.1001-7488.20151021.

    • Search Google Scholar
    • Export Citation
  • Shao WH, Jiang JM, Dong RX. 2016. A new Michelia cultivar ‘Mengxing’. Yuan Yi Xue Bao. 43(6):12191220. https://doi.org/10.16420/j.issn.0513-353x.2015-0888.

    • Search Google Scholar
    • Export Citation
  • Xu HY, Li WX, Pan YZ, Gong X. 2014. A new Michelia cultivar ‘Yunrui’. Yuan Yi Xue Bao. 41(2):403404. https://doi.org/10.16420/j.issn.0513-353x.2014.02.021.

    • Search Google Scholar
    • Export Citation
  • Zou YP, Zhang DL, Hutzell Z. 2022. Windows of opportunity for rooting woody stem cuttings. Proceedings of IPPS. 72:207214.

Supplementary Materials

Wenqian Zhang College of Landscape Architecture, Central South University of Forestry & Technology, Changsha, Hunan 410004, China; and Hunan Big Data Engineering Technology Research Center of Natural Protected Areas Landscape Resources, Changsha, Hunan 410004, China

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Zachary J. Hutzell Department of Horticulture, University of Georgia, Athens, GA 30602, USA

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Donglin Zhang Department of Horticulture, University of Georgia, Athens, GA 30602, USA

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Xiaoling Jin College of Landscape Architecture, Central South University of Forestry & Technology, Changsha, Hunan 410004, China; and Hunan Big Data Engineering Technology Research Center of Natural Protected Areas Landscape Resources, Changsha, Hunan 410004, China

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Qiulin Liao College of Landscape Architecture, Central South University of Forestry & Technology, Changsha, Hunan 410004, China; and Hunan Big Data Engineering Technology Research Center of Natural Protected Areas Landscape Resources, Changsha, Hunan 410004, China

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Contributor Notes

Financial support was graciously provided by various sources, including the Hunan Provincial Innovation Foundation for Postgraduate (Grant No. CX20210851), the Innovation Foundation for Postgraduate Studies at the Central South University of Forestry and Technology (Grant No. CX202101025), and The New Cultivar Development Grant offered by the University of Georgia Research Foundation (Grant No. 2521RC297295).

D.Z. is the corresponding author. E-mail: donglin@uga.edu.

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