1. Philadelphus coronarius L. (sweet mock orange)
Pl. 427 g, h;
Map 1908
Twigs with the
bark often reddish brown, commonly flaking or peeling by the second growing
season. Leaf blades with the undersurface moderately to densely hairy along the
main veins, glabrous or very sparsely hairy between the veins. Inflorescence
mostly racemes with 5–7 flowers, sometimes appearing as clusters. Hypanthium
glabrous or very sparsely hairy. Sepals 4–8 mm long, glabrous or very sparsely
hairy on the outer surface, glabrous or densely and minutely hairy along the
margins. Style 4–7 mm long at flowering, becoming slightly elongated by
fruiting, 4-lobed only toward the tip, the stigmas 2–3 mm long. Fruits 6–8 mm
long, 5–6 mm wide. 2n=26. May–June.
Introduced,
uncommon and sporadic in Missouri (native of Europe, Asia; introduced in the
eastern U.S. and adjacent Canada west to Minnesota and Missouri). Bottomland
forests, mesic upland forests, and banks of streams and rivers; also roadsides,
railroads, and alleys.
Philadelphus
coronarius has been
widely cultivated in Europe and the United States, for so long in fact that the
exact area of wild origin for the introduced plants is not known. Many
varieties and forms have been named and numerous cultivars have been developed,
including several dwarf and double-flowered forms (S. Y. Hu, 1954–1956). The
species was first reported for Missouri by Mühlenbach (1979) from his
collections in the St. Louis railyards.
Another species
of Philadelphus has been noted to persist at old homesites, but
apparently has not spread from original plantings and thus is not yet
recognized formally as a member of the Missouri flora. Philadelphus inodorus
L. (scentless mock orange) is a southeastern species that has long been
cultivated and has escaped sporadically throughout the eastern half of the
United States. Hu (1954–1956) noted specimens from plants cultivated in
Hannibal (Marion County) and the city of St. Louis early in the 20th century,
and a recent collection from a National Guard training site in Newton County
confirms the long persistence of the taxon at homesites. This species most
likely will be recorded as naturalized in Missouri in the future. It differs
from P. pubescens in its flowers with a glabrous to sparsely hairy calyx
and hypanthium, and from P. coronarius in its clusters of 1–3 flowers
(vs. 5–7) per branchlet. It also differs from both taxa in its scentless (vs.
fragrant) flowers. Hu (1954–1956) treated P. inodorus as comprising
several varieties, which are now considered trivial variants unworthy of formal
taxonomic recognition by most botanists. The Missouri materials mostly seem to
correspond to P. inodorus in the strict sense (var. inodorus of
Hu).