Species of the Month: Cucumber Magnolia

The Long Point Region is well-known for its high biodiversity, abundant wildlife, and gorgeous ecosystems. It is also home to one of the rarest tree species in Canada, the Cucumber Magnolia (Magnolia acuminata). Cucumber Magnolia, Canada’s only Magnolia species, is naturally observed in two very small areas – southern Norfolk County and the Niagara Peninsula. The Norfolk population accounts for most of the ~150 mature trees left in Canada (COSEWIC, 2010). Cucumber Tree is assessed as endangered by COSEWIC – endangerment is likely caused by its small natural distribution in Canada, exacerbated by historical deforestation in Norfolk County during the 19th century. Luckily, most of the remaining Magnolias in Norfolk County occur on conservation land, and ample habitat exists for propagation of Magnolias to expand the currently imperiled population.

 

Cucumber Magnolia is most closely related to the Tuliptree (Liriodendron tulipifera), a much more common tree species around Long Point (a stylized Tuliptree leaf can be found on Long Point Basin Land Trust’s logo), and the only other native species of the Magnoliaceae family. 

The bark of the Cucumber Magnolia is grey-brown and consists of scaly ridges divided by furrows. Leaves are alternate, oval (elliptical to obovate), and are 10 – 25 cm long. The margins of leaves are smooth, like Tuliptree leaves. In the autumn, foliage will transform into a bright-yellow color, creating a vibrant display lasting a few weeks in duration. Winter buds are plump, grey, and covered in fine hairs (like other Magnolias). The yellow to light green flowers, which are 8 -10cm in length, appear in May, after the foliage has completely emerged (this contrasts with cultivated M. kobus, Kobus Magnolia, and M. stellata, Star Magnolia, in which the flowers appear before foliage and are often white or pink in colour). The primary pollinators of Cucumber Magnolia are beetles. After pollination, an elongated green, cucumber-like fruit capsule develops, reaching 5 – 8 cm by August. In September, the capsule opens to expose red berry-like fruits.

In the Long Point Region, Cucumber Magnolias occur in moist mesophytic upland forests, which are often dominated by Sugar Maple (Acer saccharum), Beech (Fagus grandifolia), White Ash (Fraxinus americana), Tuliptree (Liriodendron tulipifera), and Bitternut Hickory (Carya cordiformis). They do not grow well in overly dry conditions (such as Oak Woodland-Savannas), or inundated, wet (such as Deciduous Swamps). Cucumber tree is shade-tolerant, able to persist in forest understories for many years before more favorable conditions (caused by disturbance) allow sunlight to penetrate the understory, accelerating the growth rate of Cucumber Magnolias and many other tree species. Like Tuliptrees, Magnolias can be massive canopy giants – capable of reaching 35 m or more in height, though they are often much smaller. Magnolias have a maximum life span of more than 300 years. 

Conservation lands have expanded substantially over the previous few decades in the Long Point Region, due to generous (and much appreciated) donations by landowners in our conservation community, and the conservation actions of Long Point Basin Land Trust, the Nature Conservancy of Canada, and other conservation organizations dedicated to protecting biodiversity and Long Point’s gorgeous, ecologically important landscapes. With a vast protected lands network already established, there is definitely some capacity to restore Magnolias in both existing forests, and former agricultural land – if Magnolia populations increase, the degree of imperilment to this magnificent tree will be reduced in the future.

Written By: 

Matthew Palarchio, Honour’s BSc in Environmental Science candidate, Western University