November 2017 in the Garden

November’s heavy hand often deals a death blow to the softer flowers and foliage that we enjoy through the early autumn. It isn’t technically winter in November, but it often feels that way. We’re lucky if the cold weather holds off so we can continue to enjoy the autumn flowers of Hesperantha (river lily), Elaeagnus (oleaster) Heptacodium (seven-son-flower) and Epilobium (zauschneria) for a little longer. Luckily, we have autumn-tinted leaves and plenty of colourful fruits to carry us when the weather turns nasty. But take a minute to consider all of evergreen foliage around us. It comes in a vast range of sizes, shapes, textures and shades of green. In our obsession for colour (other than green) in the garden we often take these important plants for granted. One need only spend a winter in a colder climate to be reminded of the value of the diversity of broad-leaved evergreens we can grow in Vancouver.

On a long list of evergreens at UBC Botanical Garden, bamboos stand out as one of our larger collections. Located primarily in the David C. Lam Asian Garden (there are also bamboos in Nitobe Memorial Garden), our bamboos comprise older established plants and a number that are more recently acquired. A large proportion came to the Garden as a gift from Matt Lang and his company, Bamboo Botanicals Garden & Nursery, and some exceptional specimens were also donated by bamboo collector and former Botanical Garden horticulturist, Samuel Normandeau.

Native to mostly tropical and warm temperate regions of the world, bamboos range from diminutive groundcovers less than 20 cm tall to tropical forest giants, 30 m tall with culms (above-ground stems) more than 30 cm in diameter. Our tallest species, Phyllostachys vivax (Chinese timber bamboo), which is located along Flanagan Trail near Purdom Trail, is a fast-growing species—and a good source of edible bamboo shoots—with bright green culms known to grow to 20 m, although they seldom reach 10 m here. There is a golden-stemmed selection with green longitudinal stripes—P. vivax ‘Aureocaulis’—along Upper Asian Way east of  Wilson Trail. It is still small, but its striking culms will eventually undoubtedly define this area of the garden. There are perhaps sixty or more bamboo species that could be considered cold hardy in Vancouver, most of these from China and Japan, but hardy bamboos also hail from the Himalayas and southern South America. Variation within these species is considerable, and many of the hundreds of selections that are available in commerce could potentially be cultivated here.

Bamboos are classified as either running—i.e., growing from a wide-spreading network of sparsely branched rhizomes (horizontal underground stems)—or clumping—i.e., growing from rhizomes that are densely branched and compact. The Botanical Garden’s collections of approximately fifty different bamboos includes almost equal numbers of running and clumping types. Most people are aware of the habits of the running bamboos, and are usually warned away from acquiring them, unless provision is made to effectively contain their wandering rhizomes. In the Botanical Garden, there is not only plenty of room for these magnificent plants, but the combination of root competition from established conifers, summer drought and impoverished, shallow soils, tends to severely limit their growth away from amended and irrigated areas.

Chimonobambusa tumidissinoda

Chimonobambusa tumidissinoda

One of our most distinctive runners is Chimonobambusa tumidissinoda (walking stick bamboo), a rarely cultivated Chinese species with pea-green upright culms that have curiously flanged nodes (the node is the solid, enlarged part of the culm where branches arise). This species is so aggressive that the Asian Garden Curator, Andy Hill, created an island surrounded by turf in Wharton Glade so that escaped stems can be easily identified and dispatched. We have plenty of smaller running bamboos, including the astoundingly vigorous Pleioblastus humilis (dwarf bamboo) which effectively covers the slope between the boardwalk and the pond at the Garden’s entrance. This species eventually becomes ragged and pest-infested when left to its own devices, and like most other low-growing bamboos, benefits from a serious “haircut” (i.e., being mowed to the ground) every three years or so.

Solid-culmed bamboos are rare, as hollow stems are generally the rule, but the one hundred and seventy or so species of the New World (North and South American) genus Chusquea all have solid culms. More unusual than attractive, C. montana (Argentine mountain bamboo) grows to only 2 or 3 m tall. The culms are mostly stiffly erect and densely clothed with small tough leaves. There is a plant near the parking lot close to the Reception Centre patio.

Fargesia scabrida

Fargesia scabrida

Over the last twenty years or so, clumping bamboos, which are generally viewed as being better behaved in gardens, have come to the fore, to some extent eclipsing the appeal of the running species. Clumpers represent the majority of our newer accessions. Among the cold-hardiest are species in the genus Fargesia, of which we have a good selection. The orange-stem bamboo, F. scabrida is well on its way to forming a large clump of 4-m-tall culms at the corner Lower Asian Way and Kingdon Ward Way. Culms of F. scabrida (as well as the culms of all other bamboos) emerge with stiff, wrapper-like modified leaves called culm sheaths. Culm sheaths are borne at every node and are ultimately deciduous, but may persist for some time, especially near the culm base. Later, when branches arise at the nodes, they are covered by similar but much smaller branch sheaths. In F. scabrida, these sheaths are an attractive rusty orange. Another desirable bamboo, but for spaces with limited room (such as in containers), is F. nitida (fountain bamboo). We have at least three selections of this diminutive species. Our most distinctive is a cultivar named ‘Juizhaigou 2’, which has slender, upright, purple-brown culms (burgundy-black in the sun) and short branches densely clothed in soft green leaves. Juizhaigou (pronounced joo-zay-gow) is a park in Sichuan Province (in western China near Tibet) where a number of fargesias have been selected from wild populations. ‘Juizhaigou 2’ is located at the top of Rehder Trail, near the Service Yard gate. Although not as cold hardy as the fargesias, the borindas represent another important group of clumping bamboos. Borinda macclureana is an exceptionally elegant bamboo from southeastern Tibet, relatively new to cultivation. Our plant, which is on Maack Trail near where it intersects with Maximowicz Trail, has slender, impossibly wide spreading, arching culms with purple branches and long (up to 25 cm), draping leaves. Finally, the genus Yushania (named for the famous mountain in Taiwan known as Yu Shan) is often listed as a genus of clumping bamboos. However, the truth is that the species clump, but they run between clumps! Judging by our Yushania anceps, a beautiful Himalayan species with fresh green leaves and 2-m-tall culms, this is not a bamboo for the faint of heart. Once it was established here, this bamboo spread quickly outward on all sides, with loose, lush drooping clumps of bright green culms. You can find us beating it back on Beer Trail just south of the Campbell Glade.

Submitted by Douglas Justice, Associate Director, Horticulture and Collections

 

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