Osmanthus cooperi Hemsley (Osmanthus, Oleaceae), an endemic wild osmanthus species in China, is sporadically distributed on slopes, and in shady and moist places in woods of valleys and ravines in Zhejiang, Jiangsu, Jiangxi, Fujian, Anhui, Hunan, and Sichuan provinces (Chang et al. 1996). Because of the rich fragrance and high resistance, O. cooperi is frequently used as a rootstock for fragrant potted plants and grafting of Osmanthus cultivars, which is another excellent germplasm resource in this genus with high potential for breeding new aromatic cultivars besides Osmanthus fragrans (Zuo 2013).
At present, there is only one cultivar of O. cooperi used in the garden market, namely Xuegui, which is fertile (Xiang and Liu 2008). In 2021, a new cultivar, Meixue, jointly selected from O. cooperi by Nanjing Forestry University and Huangshan Vocational Technical College, was granted a patent by the State Forestry and Grassland Administration of China (Authorization No. 20210460). This new cultivar enriches the germplasm resources of Osmanthus and has tremendous application prospects.
Origin
In Spring 2010, a case of a sterile variant plant was found in a batch of seed-sown seedlings of O. cooperi in Runyi Ecological Garden, Huangshan, Anhui, China. The maternal parent trees of O. cooperi ‘Meixue’ are 3 to 5 m tall, with a spherical crown and dense branching (Fig. 1A). After years of propagation (Fig. 1B) during 2013 and 2019, it was noticed that the special seedlings from maternal parent trees were highly resistant and vigorous, and the phenotypes including white, aromatic flowers and conical abortive pistils were stable over multiple generations, proving excellent stability without degeneration or segregation.
Morphological characteristics (A–F) of Osmanthus cooperi ‘Meixue’ and the floral comparison (G–I) among ‘Meixue’, ‘Xuegui’, and O. cooperi. The maternal parent trees (A), and the cuttage seedlings (B) in Runyi Ecological Garden, Huangshan, Anhui, China; the leaf branches (C), and the leaf variants (D); the flowering branch in full bloom (E), and the corolla size (F) of ‘Meixue’. The flower branches with abortive pistil of ‘Meixue’ (G); the flowering branch with young fruit of ‘Xuegui’ (H); and the flowers with fertile pistil of O. cooperi (I).
Citation: HortScience 58, 5; 10.21273/HORTSCI17041-22
Morphological characteristics (A–F) of Osmanthus cooperi ‘Meixue’ and the floral comparison (G–I) among ‘Meixue’, ‘Xuegui’, and O. cooperi. The maternal parent trees (A), and the cuttage seedlings (B) in Runyi Ecological Garden, Huangshan, Anhui, China; the leaf branches (C), and the leaf variants (D); the flowering branch in full bloom (E), and the corolla size (F) of ‘Meixue’. The flower branches with abortive pistil of ‘Meixue’ (G); the flowering branch with young fruit of ‘Xuegui’ (H); and the flowers with fertile pistil of O. cooperi (I).
Citation: HortScience 58, 5; 10.21273/HORTSCI17041-22
Morphological characteristics (A–F) of Osmanthus cooperi ‘Meixue’ and the floral comparison (G–I) among ‘Meixue’, ‘Xuegui’, and O. cooperi. The maternal parent trees (A), and the cuttage seedlings (B) in Runyi Ecological Garden, Huangshan, Anhui, China; the leaf branches (C), and the leaf variants (D); the flowering branch in full bloom (E), and the corolla size (F) of ‘Meixue’. The flower branches with abortive pistil of ‘Meixue’ (G); the flowering branch with young fruit of ‘Xuegui’ (H); and the flowers with fertile pistil of O. cooperi (I).
Citation: HortScience 58, 5; 10.21273/HORTSCI17041-22
Description
Under the same site conditions, morphological observation and data collection were carried out on 30 flowering asexual individuals of O. cooperi ‘Meixue’, O. cooperi ‘Xuegui’, and O. cooperi. The differences in morphological characteristics among ‘Meixue’, ‘Xuegui’, and O. cooperi are shown in Table 1, and the flower color was determined according to the Royal Horticultural Society Color Chart (RHS-CC) (Royal Horticultural Society 2007). The results showed that ‘Meixue’ significantly differed from the other two in quantitative traits of leaf length, flower numbers, pedicel length, and corolla size, as well as the qualitative traits on entire leaves, fragrant white flowers, abortive pistils, and nonseeding.
Comparison of morphological characters of ‘Meixue’ with ‘Xuegui’ and Osmanthus cooperi.
Habit and branching.
Evergreen small trees, 3 to 5 m tall, crown spheroid; bark gray-brown, unlobed, lenticels obvious; branching denser, oblique up, branchlets gray-white (Fig. 1C).
Leaves.
Leaf blade is smaller than ‘Xuegui’ and O. cooperi, lanceolate, 7.3–9.5 cm × 3.2–3.7 cm, dark green, thicker, spreading; veins inconspicuous, margin entire (Fig. 1D).
Flowering.
One to three flower buds in each leaf axil, with six to eight flowers (Fig. 1E); pedicel 10 to 13 mm, glabrous; corolla campanulate, 5.3 to 7.2 mm in diameter (Fig. 1F), aromatic; four petals, long elliptic to navicular, apex rounded, slightly introrse, pure white (RHS-CC 2C); pistil conical, obviously abortive and nonseeding (Fig. 1G), whereas the pistil was fertile and seeding in ‘Xuegui’ (Fig. 1H) and O. cooperi (Fig. 1I). Blooming is from the first 10 d of October to the first 10 d of November.
Cultivation Technology and Application
O. cooperi ‘Meixue’ prefers light and warmth, and tolerates drought and barrenness, which shows that it is highly adaptable. The most suitable propagation method for O. cooperi ‘Meixue’ is cuttings or grafting, and the most appropriate cultivation methods are in the ground or pots (Dang et al. 2020). It can be cultivated in the open field to the south of the Yangtze River, but in northern areas, it needs to be planted in insulated sheds. O. cooperi ‘Meixue’ is suitable for deep, well-drained, fertile, and humus-rich medium acid peat or sandy loam soils. Thorough watering should follow dryness, and fertilizer should be applied sparingly and diligently. Prune the plant at least once before branching out, leaving more than three main branches. Pruning should be uniform and the crown should be bun-shaped. It also can be pruned to suit the needs of courtyards, parks, road greening, etc. Because of the strong resistance, pure white flowers, and rich fragrance, O. cooperi ‘Meixue’ should be an excellent germplasm for landscape ornamentation.
Availability
The owners of O. cooperi ‘Meixue’ are Nanjing Forestry University (Nanjing, China) and Runyi Ecological Park (Huangshan, Anhui, China). Contact Min Zhang (E-mail: zhangmin@njfu.edu.cn) for inquiries.
References Cited
Chang, MC, Qiu, LQ, Wei, Z & Green, PS 1996 Osmanthus 286 292 Wu, Z, Raven, P & Hong, D Flora of China. Vol. 15 Science Press Beijing, China Missouri Botanical Garden Press St. Louis, MO, USA
Dang, W, Xie, YM, Sun, J, Fan, JL & Wang, F 2020 Study on cutting propagation, cultivation management, and flowering regulation of Osmanthus fragrans Anhui Agri Sci Bull. 26 4 58 59 https://doi.org/10.16377/j.cnki.issn1007-7731.2020.04.025
Royal Horticultural Society 2007 Royal Horticultural Society Color Chart 5th ed Royal Horticultural Society London, UK
Xiang, QB & Liu, YL 2008 An illustrated monograph of the sweet osmanthus cultivars in China Zhejiang Science & Technology Press Hangzhou, China
Zuo, MY 2013 Study on the phenotypic variation and genetic diversity of Osmanthus cooperi Hemsl (MS Thesis) Nanjing Forestry University Nanjing, China
