The Cornus Conundrum

Species name: Cornus capitata

Common name: Himalayan dogwood

Location: Ontario

Despite this looking a whole lot like the Japanese Dogwood in a previous blog post (also called the Chinese dogwood; read all about it HERE), I believe very strongly that this is a different species; at least, that this individual tree would be classified as a different species according to currently recognized species. Whether or not a DNA analysis would confirm or deny that these are, in fact, two separate species is probably up for debate. I think the key here lies in the fruit and in the leaves.

The fruit of the Japanese dogwood is quite dense. Once you get through the tough outer rind there is a a sweet flesh on the inside, but not much of it because the seeds are quite large in comparison to the size of the fruit. In the Himalayan dogwood (native to, you guessed it, the Himalayas where it is not overly common), the fruit is much larger, much juicier, but also much less sweet. This series of photographs is actually of my neighbour's tree (I'm glad they don't question me sneaking around the front of their property, taking pictures of their plants!), and I'll be the first to admit that I tried one of the fruits. It was bad. Really bad. The Wikipedia page of the Himalayan dogwood doesn't say anything about the fruit being tasty (it does say edible but bitter, which would be spot-on based on my experience; read the entire paragraph worth of information about it HERE), but I figured at the time it was worth a shot. I don't recommend it.

The leaves of the Japanese dogwood have rather non-descript borders, exactly as you would imagine from a dogwood. Smooth leaves on the top and the bottom, a prominent primary vein down the centre of the leaf with equally prominent secondary veins coming off of that running almost to the leaf edge, and very few easily visible tertiary veins. The Himalayan dogwood is quite similar, except that the leaf edge is a much lighter colour than the rest of the leaf and almost provides a border around the outside. When felt, the leaves of the Himalayan dogwood are also much hairier than the Japanese dogwood (which have very glossy, green leaves).

The Himalayan dogwood, whether on purpose or by accident, is gaining popularity as an ornamental plant in North America. It is much more cold-tolerant than its Japanese relative so is more favourable for slightly more northern climates. Don't expect it to survive in Alaska, however; it's not quite that cold-tolerant! The fruit of the Himalayan dogwood are also much showier than the Japanese dogwood, providing a spectacular show in the fall, and have very similar showy inflorescences in the spring. Because the fruit is so much more bitter, it doesn't have the sugar content required to be of great use in the winemaking industry (like in which the Japanese dogwood is sometimes used) and for the same reason is much less edible. The flip side of this is that it is much less appealing to herbivores and so the fruit remain on the tree until they rot (and provide an equally spectacular odor; picture the smell of fermenting, rotting apples in an orchard on warm days in the fall...). There are some species of insect that will consume the fruit, but these are relatively few.

These flowers aren't for the dogs!

Species name: Cornus kousa

Common name: Chinese dogwood, Kousa dogwood, Korean dogwood, Japanese dogwood

Location: Ontario

Based on the common names of this species, it should be incredibly obvious where this plant is native: The Himalayan highlands of China, mountainous regions of Korea, and the mountains of Japan. The bright, showy flowers are produced in May and June, with the red fruits ripening into September. Despite having two of these trees in our yard, I have yet to see the fruit actually successfully grow into a new plant so I highly doubt it has any kind of invasive ability. That being said, there is a native species of this same genus that produces brilliant white flowers that could be planted instead. The downside of the native species (Cornus florida) is that it is very susceptible to a fungal disease called "anthracnose," and the Asian species is much more resistant to this disease. For this reason it is favoured amongst horticulturalists.

Despite appearances, those aren't actually flowers that appear in the photos above. The pink or yellow "petals" are actually bracts that surround the flower, not the flower itself. The flowers are rather inconspicuous and are located in the ball of plant tissue in the middle of the bracts. Each tiny flower in the inflorescence must be pollinated in order for that inflorescence to turn into a fruit. All of the maturing ovaries of the flower merge into one fruit, kind of like what happens in a pineapple. The fruits themselves are actually edible, and are sometimes used to produce the unique flavour of some fruit wines without adding too much sweetness.

There are quite a few references to dogwoods in popular culture, the most relevant (to this blog, at least) being that many farmers back in the "olden days" referred to cold snaps in the spring as "dogwood winters." The implication of this is that it's not safe to plant this year's crops until the dogwoods have started flowering, as flowering will be delayed in suboptimal conditions.