Magnolia

Magnolia Collection

Peak Interest: Late April, Early May
Arboretum, Rock Garden

These big, beautiful trees feature iconic cup-shaped blooms in white, pink, purple and yellow.

RBG’s magnolia collection reaches peak bloom anywhere between April and May given the type of climatic conditions per year. These plants produce spectacular flowers in a range of colours including white and cream through to pale to deep pink, purple, rose and less commonly soft yellows. Many are fragrant. Check out the species and cultivars of Magnolia salicifolia which have a very unusual licorice type fragrance.  The magnolias on the western side of the Arboretum are a memorial to Lester Husband a local architect whilst the eastern collection is a memorial to R.A. Sims a past member of RBG staff.

About Magnolias

The genus magnolia is fascinating. Here a few fascinating facts about this beautiful spring flowering plant.

Conditions and Care

Magnolia are deciduous or evergreen trees or shrubs, with large showy, often fragrant flowers. The flowers usually open in spring before the leaves and are often followed by colourful cone-like fruit. The leaves, more often than not, are large and oval in shape. A location with full sun or partial shade is ideal along with soil that is organically rich, moist but well drained. Most magnolias prefer to be planted in areas that avoid strong wind and frosts as in severe years the latter can cause damage to flower buds.

Magnolias can be intolerant of urban conditions but a particular cultivar, ‘Galaxy’ has been planted as a demonstration street tree in the RBG Centre parking lot. Aside from some drought stress symptoms in 2012 and 2013 this cultivar seems to tolerate these conditions. Magnolias can be planted en masse for spectacular effect or equally can be planted in a bed, border or lawn as a specimen plant. Many cultivars are available at your local garden centre and once planted these plants will reward you for years to come.

Magnolia Genus

Magnolia is a large genus thought to currently consist of around 240 naturally occurring species in the wild. The primary natural range of Magnolia species is in east and southeast Asia with a secondary centre in eastern North America, Central America, the West Indies, and some species in South America. This is termed a disjunct distribution meaning plants are separated geographically over diverse locations. This could be caused by range fragmentation including continental drift, mountain building or changes in sea level or by habitat fragmentation including population disruption, isolation of populations or even extinction.

131 species are currently threatened with extinction and of those 89 are endangered or critically endangered. The conservation of magnolias and other plant species is one of the reasons that makes the work of botanical gardens so critical for the future of the planet. Look out for Magnolia acuminata (Cucumber Tree) which is Ontario’s own native magnolia and is displayed in RBG’s collection.

Cultivars and Hybrids

In a horticultural setting magnolia are a highly desirable genus and much loved plant. Because of this popularity over 1000 cultivars (cultivated varieties) have been bred by magnolia hybridisers and enthusiasts and more appear every year. Much work has been spent on trying to introduce new varieties with flowers that display elusive and more unusual colours. Soft yellow in recent years has become a highly desirable flower colour In RBG’s collection look out for Magnolia ‘Butterflies’ and Magnolia × brooklynensis ‘Yellow Bird’ to see these spectacular flowers in shades of yellow.

History of Magnolias

Whilst the flowers of magnolias are considered to be some of the most spectacular of spring flowering plants they are also amongst the most primitive of flowering plants. It is thought that the flowers evolved to encourage beetle pollination which appeared much earlier than more modern insects such as bees. This pollination mechanism is the reason that magnolia flowers are so large and sturdy.

The genus Magnolia was named to honour the French botanist Pierre Magnol (1638 – 1715). Magnol is of lasting botanical importance as he was one of the innovators of the current botanical scheme of classification. He was the first to publish the concept of plant families, a natural classification, in which groups of plants with associated common features were described.

Plant Uses

Whilst many magnolias are planted purely for their beauty in gardens around the world some species also have additional uses. The exploitation of plants by people is called economic botany. Economic botany explores the ways humans use plants for food, shelter, medicines, textiles, and much more. Ontario’s own species, Magnolia acuminata grows to a very large size and so is harvested as a timber tree in eastern North America.