Philadelphus Explained

Philadelphus (^[1]) (mock-orange) is a genus of about 60 species of shrubs from 3–20 ft (1–6 m) tall, native to North America, Central America, Asia and (locally) in southeast Europe.

They are named "mock-orange" in reference to their flowers, which in wild species look somewhat similar to those of oranges and lemons (Citrus) at first glance, and smell of orange flowers and jasmine (Jasminum). But Philadelphus is a basal asterid, not closely related to Jasminum (advanced asterids), and among the eudicots quite distant from Citrus (advanced rosids). An entirely misleading name for Philadelphus that is sometimes encountered is syringa;^[2] this properly refers to the lilacs, which are fairly close relatives of jasmine. The connection of the two shrubs lies in their introduction from Ottoman gardens to European ones, effected at the same time by the Holy Roman emperor's ambassador to the Sublime Porte, Ogier Ghiselin de Busbecq, who returned to Vienna in 1562. The two shrubs appear together in John Gerard's Herball, as "Blew Pipe" (the lilac) and "White Pipe Tree", for the woods of both are pithy and easily hollowed out.^[3]

Philadelphus is named after an ancient Greek king of Egypt, Ptolemy II Philadelphus.

Description

Most are deciduous but a few species from the south of the genus' range are evergreen. The leaves are opposite, simple, with serrated margins, from 0.5-6 inches (1–14 cm) long. The flowers are white, with four petals and sepals, 0.5-2 inches (1–4 cm) diameter, and commonly (but not in all species) sweetly scented. The fruit is a small capsule, containing numerous small seeds. The bark is thin and flaky, finely shredding in longitudinal strips.

Ecology

Mock-oranges are used as food plants by the larvae of some Lepidoptera species including the engrailed (Ectropis crepuscularia). A noted pathogen of the sweet mock-orange (P. coronarius) is the undescribed proteobacterium called "Pseudomonas tomato" (pv. philadelphi).

Cultivation

For a long time, Philadelphus coronarius was the only mock-orange of gardens, though some adventurous Americans grew the native P. inodorus that Mark Catesby had discovered growing on the banks of the Savannah River. It appeared in Lady Skipwith's garden lists and George Washington ordered some from Bartram in 1792.^[4] Mock-oranges are popular shrubs in parks and gardens, grown for their reliable display of late spring flowers; the scented species are particularly valued. In addition to the species, there are numerous garden origin hybrids and cultivars available, selected for doubleness and large flowers, with some compromise as to scent.

AGM cultivars

The following hybrid cultivars have gained the Royal Horticultural Society's Award of Garden Merit:-^[5]

• ’Aureus’ (P. coronarius)^[6]
• 'Beauclerk'^[7]
• 'Belle Étoile'^[8]
• ’Innocence’^[9]
• 'Manteau d'Hermine'^[10]
• 'Sybille'^[11]
• ’Variegatus’ (P. coronarius)^[12]

In culture

Lewis' mock-orange (P. lewisii) is the state flower of Idaho.^[13]

Selected species

Asia

• Philadelphus brachybotrys (southeast China)
• Philadelphus delavayi – Delavay's mock-orange (southwest China)
• Philadelphus incanus (Hubei, Shaanxi)
• Philadelphus kansuensis – Chinese evergreen mock-orange (northwest China)
• Philadelphus laxiflorus (Gansu, Hubei, Shaanxi)
• Philadelphus laxus Schrad. ex DC. – Japanese mock-orange (Japan; formerly P. satsumi
• Philadelphus purpurascens (southwest China)
• Philadelphus satsumanus – Downy Japanese mock-orange (Japan)
• Philadelphus schrenkii – Korean mock-orange^[14] (northeast China, Korea, southeast Russia)
• Philadelphus sericanthus (Sichuan, Hubei)
• Philadelphus pekinensis – Beijing mock-orange (northern China)
• Philadelphus subcanus (southwest China)
• Philadelphus tenuifolius – Slenderleaf mock-orange (Korea, southeast Russia)
• Philadelphus tomentosus – Fuzzy mock-orange (Himalaya)
• Philadelphus triflorus – Himalayan mock-orange (Himalaya)

Europe

• Philadelphus caucasicus – Caucasus mock-orange (Caucasus) – likely syn. of P. coronarius
• Philadelphus coronarius – Sweet mock-orange, English Dogwood (southeast Europe)

Pancontinental hybrids

• Philadelphus × lemoinei (horticultural hybrid)
• Philadelphus × purpureomaculatus (horticultural hybrid)
• Philadelphus × virginalis (horticultural hybrid)

External links

• Philadelphus. x.

Notes and References

1. Sunset Western Garden Book, 1995:606–607
2. Web site: State Symbols USA: Idaho State Flower. 2 October 2014 .
3. Alice M. Coats, Garden Plants and Their Histories (1964) 1992, s.v. "Philadelphus".
4. Ann Leighton, American Gardens of the Eighteenth Century: 'ForUse or for Delight' , 1976, s.v. "Mock-orange", "Philadelphus".
5. Web site: AGM Plants - Ornamental . July 2017 . 76. Royal Horticultural Society . 24 April 2018.
6. Web site: RHS Plantfinder - Philadelphus coronarius 'Aureus' . 24 April 2018.
7. Web site: RHS Plant Selector - Philadelphus 'Beauclerk'. 6 February 2021.
8. Web site: RHS Plant Selector - Philadelphus 'Belle Étoile'. 6 February 2021.
9. Web site: RHS Plantfinder - Philadelphus 'Innocence' . 24 April 2018.
10. Web site: RHS Plant Selector - Philadelphus 'Manteau d'Hermine'. 6 February 2021.
11. Web site: RHS Plant Selector - Philadelphus 'Sybille'. 6 February 2021.
12. Web site: RHS Plantfinder - Philadelphus coronarius 'Variegatus' . 24 April 2018.
13. Web site: State Emblems of Idaho. Idaho Secretary of State. 12 January 2015. https://web.archive.org/web/20120313090503/http://www.sos.idaho.gov/ELECT/Emblem.htm. 13 March 2012. dead.
14. Book: English Names for Korean Native Plants. Korea National Arboretum. 2015. 978-89-97450-98-5. Pocheon. 5690. 8 December 2016. Korea Forest Service. dead. https://web.archive.org/web/20170525105020/http://www.forest.go.kr/kna/special/download/English_Names_for_Korean_Native_Plants.pdf. 25 May 2017.