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UBC Publications

Davidsonia Dec 1, 1971

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Winter 1971
*» V Cover
Forest grove of 'Western red cedar', Thuja plicata.
An ink sketch by Mrs. Lesley Bohm
Winter 1971
Davidsonia is published quarterly by The Botanical Garden of The University of British
Columbia, Vancouver 8, British Columbia, Canada. Annual subscription, four dollars.
Single numbers, one dollar. All editorial matters or information concerning subscriptions
should be addressed to the Director of the Botanical Garden.
A cknowledgements
The pen and ink illustrations are by Mrs. Lesley Bohm. Dr. C.J. Marchant contributed the
photographic material. Vines and  Climbers  at  UBC
Calystegia septum
The common twining convolvulus
"Ivy-clad halls of learning". This is the picture most people seem to
have of the University. It was certainly true of the traditional European
institutions and the early colleges of eastern North America. The
University of British Columbia, however, is representative of many of
the newer schools of higher learning not bound by tradition. The
campus is dominated by buildings constructed since the second world
war. Their architecture is intended to reflect the trends of the decade in
which they were designed. Vines might seem to be out of place,
although some critics might wish to see them used to mask some of the
architecture which does not appeal to them. There is little room,
though, for negative thinking in design and it is better to suggest that
the skilful use of vines, climbers and selected wall plants will enhance
the architecture and help give us a sense of unity to the total campus.
The early depression years of the Thirties saw the construction of a
number of temporary buildings to provide the University with
inexpensive facilities for administration, the faculties of agriculture,
arts, applied science and forestry and an auditorium. These substantial
frame stucco buildings have become semi-permanent, since they all are
still in use. Most of them were planted with Virginia Creeper,
Parthenocissus quinquefolia and Boston ivy, P. tricuspidata. In spite of
the usual recommendation to avoid tight clinging vines on a stucco
surface, these do not appear to have noticeably damaged the stucco
over the years. The principal maintenance problem has been to keep
them trimmed from the windows and eaves. Several times walls have
been stripped down and the vines cut back hard for building alterations,
following which the rejuvenated climbers have reached the top again
within two or three growing seasons.
Other climbers were planted on either side of the main entrances to
several of these buildings and are still there. Two of the twining type,
needing some support, are Dutchmans-pipe, Aristolochia durior and
Wisteria, Wisteria sinensis. The former, with its huge leaves and
fascinating pipe-shaped flowers, adds an exotic touch; Wisteria, with its
long chains of mauve flowers in May spreads the scent of a field of
clover throughout the buildings.
At the entrance of the Women's Gymnasium — gone now, replaced
by a high-rise office tower — there used to be a Trumpetcreeper,
Campsis radicans. This vine seldom bloomed profusely, obviously
requiring more heat than is afforded by the West Coast summers. The
bright orange trumpets did, however, provide a bit of colour to a rather
drab building.
37 38
Gone too are the actinidias, Actinidia chinensis,
which used to grace the entrance of the
Horticulture-greenhouse complex. Growing here at its
limit of hardiness, it did not bloom or set the edible
"gooseberry" fruit. It was more likely a casualty of a
severe winter than of construction. It is recalled for its
huge leaves and colourful new growth.
More recently another deciduous creeper has made its
appearance on campus. This is the climbing hydrangea,
Hydrangea anomala var. petiolaris. It was first planted
on the west wall of the Home Management House where
it is equally attractive in early summer, with its white
blooms, as in winter when its tightly clinging framework
of branches makes a delightful pattern on any
permanent wall. Newer plantings at the Faculty Club
seem slow to get established, but this is to be expected
with the climbing hydrangea which seems to need a year
or two of adjustment before "taking off.
Rapid growing vines are seldom used in permanent
plantings. The Silver Fleece-vine, Polygonum aubertii, is,
however, represented on campus. It is most vigorous and
must be kept under control. There was evidence of this
last summer when it started to take over a nearby
Japanese Maple.
Clematis, although well suited to West Coast
conditions, has not been planted extensively on the
University campus. One large planter near the Music
Building has been filled with Clematis montana var.
rubens, the Pink Anemone Clematis. This has draped
over the planter wall, making a great show in late May.
Other clematis, C. X fackmanii cultivars and the
evergreen C. armandii have been confined to a nursery
location, growing on the lath houses covering some of
the Rhododendron collection.
A wide range of deciduous climbers has always been
offered by the West Coast nurseries. It is interesting to
note, however, the development of a new nursery
operation in this area specializing in clematis. This surely
Parthenocissus tricuspidata, the Boston
ivy, on the west wall of the Mathematics
Aristolochia durior, the Dutchmans-pipe, over the north
entrance of the Mathematics Annex building. The eight inch
diameter leaves give the plant an exotic appearance i    i
indicates a well justified increasing interest in this climber
which is available in such variety and which is so well suited
to the climate of southwestern British Columbia.
Evergreen climbers have not been planted extensively on
campus, although various forms of English ivy, Hedera
helix, are seen throughout Vancouver and Victoria. Early
campus use of this vine was restricted to covering old forest
stumps. Over the years, possibly because it did not have far
to climb, the ivy has assumed its adult form, with its
shrubby habit of growth, simpler leaves and bearing
greenish flower clusters and black fruit.
The natural form of Hedera helix has been planted and
has reached the top of the tall power house addition within
the past decade. A cultivar, 'Digita', sometimes called
Crowsfoot ivy, has completely covered the west wall of the
Law Building. It was planted too at the foot of a wall near
the Faculty Club, where it has grown up and over, trailing
down to make a complete cover of the south face of the
wall facing the parking lot.
English ivy has been adopted as the favorite nesting
place of Vancouver's unique Crested Myna population. This
chatty  bird, like a Starling with white wing tips, was
Parthenocissus tricuspidata 'Veitchii', in
winter condition on the wall of the UBC
Forestry-Agriculture building
Hydrangea petiolaris trained on
a wall of Home Management
House showing the attractive
branching pattern of the winter
twigs imported from Hong Kong about the turn of the century. Found only in the Vancouver area and across the
Strait of Georgia at Nanaimo, it is noted as a mimic.
An increasingly popular use for Hedera helix is for ground cover planting. The variety baltica, being most
vigorous, is used extensively.
There is no indication that the use of vines on newer University buildings will be extended. However, the
story of climbing plants on this campus would not be complete without reference to the Parthenocissus
tricuspidata 'Veitchii' which appeared on the plain brick wall of the inner court of the Forestry-Agriculture
building. A professor, nearing retirement, whose office window faced this blank brick facade, planted two
vines. He has tended them and carefully measured their growth. In four years they have reached the top of
the three storey structure. A permanent plaque has been attached to the wall to acknowledge this unusual
English ivy, Hedera helix 'Digitata', completely covers a wall fronting the UBC Faculty Club
40 Thuja   plicata Donn ex D. Don in Lamb.
Member of the Family Cupressaceae
Natural Distribution
Thuja plicata occurs in the coastal regions of south Alaska from Sumner Strait south through the coastal
ranges of British Columbia through western Washington and Oregon to northern California where it is
limited to the ocean side of the coast ranges in the fog belt. It extends eastwards to the western slope of the
Continental Divide at latitude 54°30'N and thence south into the Selkirk, Bitterroot and Salmon River
Mountains of Idaho. In B.C. it is a common forest tree west of the Cascades and also occurs in scattered
pockets and on alluvial flood plains in the Similkameen and Okanagan Valleys.
The habitat is humid with abundant precipitation (annual average 30" — 60", to 100" at higher
elevations) and atmospheric humidity. It favours cool summers and mild winters. Thuja plicata is generally
found on stream sides, moist flats and ravines, terraces and gentle lower slopes, from sea level in the north
to 7000' in the Rockies of Idaho, where however the trees are very stunted. It grows to 2400' in the Coast
Range but to 4500' in the Selkirks. It sometimes occurs in pure stands over small areas but is usually
scattered among other species, especially in hemlock/spruce forest.
Large evergreen, aromatic, monoecious tree with broad tapering strongly buttressed base, 150 — 175
(—200) feet high, with a diameter at the base of 5 — 8 (—16) feet. Trunks are often hollow in older trees.
Young trees have a narrow conical and irregular crown with branches which reach to the ground while in
older trees the crown extends in width becoming short and blunt and often with a dead top. In densely
crowded stands the lower branches are lost after the tree reaches about 80' but open grown trees retain
their foliage to the ground. The slender branches curve upwards while young but with age they form a long
downward graceful curve, turning upwards only at the ends.
The root system is shallow and widespreading but strong, although it may become deeper in a dry
location. The trees depend for their support in nature largely on the intermingling of their roots with those
of other trees.
The bark is thin (seldom over 7/8" thick), scaly, divided into broad rounded ridges by irregular shallow
fissures, separating into fibrous strips, tough, bright cinnamon red or brown.
Twigs are short and horizontal but tend to spread or slightly droop and then upturn with age, smooth,
with many branchlets disposed in one plane and repeatedly two-ranked forming flat sprays. The branchlets
are thickly covered with leaves, bright green becoming cinnamon brown, then dark lustrous brown often
with a purplish tinge after the leaves have been shed.
Buds are naked.
Mature leaves are opposite, scalelike, closely appressed, green to dark yellow green and shining above,
distinctly darker beneath with a bluish bloom and with frequent white triangular spots. On the leading
shoot the leaves are parallel to the axis, ovate, long pointed with conspicuous resin glands beneath, about
6.5 mm long. On the lateral branches the leaves are shortly pointed, closely overlapping, about 3 mm long.
They occur in 4 longitudinal rows, the lateral pair compressed and prominently keeled and nearly
concealing the other pair. They are usually shed after 2-5 years. Aromatic when bruised.
Wood is pinkish or reddish brown when freshly cut becoming dark brown with exposure. It is aromatic,
attractive, soft, lightweight, relatively low in strength, brittle, medium to coarse but very straight grained,
remarkably durable, easily split and free from pitch or resin.
Flowers occur in April — May (to early June at higher elevations). The female flowers are solitary on
short branches, about 10 mm long, ovate, with 8-12 opposite ovate, acute, leathery scales in pairs, the
middle 2 or 3 pairs only are fertile bearing 2 erect pinkish ovules at the base. The male flowers are terminal
on short lateral branchlets, numerous, subglobose to ovate, about 10 mm long, (3-) 4 pairs of stamens each
with (3—) 4 subglobose pollen sacs, 4 — 6 peltate scales, yellowish or brownish in colour.
41 42
Figure ]      Thuja plicate    A. Leafy btanch wiih mature cones.   B. Male rones and uprighi immature female enrw.    C. Winged seed
D. Habit of mature tree.     K. Portion of trunk showing strips uf bark. The cones are ovoid-ellipsoid, erect, with ovoid leathery scales acute and mucronate at the tip, bluish
green becoming brown, 8 - 10 (—12) mm long at maturity. The cones mature by mid-August of the first
year when they turn downward before seedfall in late August or early September when the weather is cold
with the humidity below 50%. Empty cones remain on the tree until the following summer.
Seeds are 6 — 7 mm long, ovoid, acute, compressed, light chestnut brown with a pair of small slightly
unequal wings which are not quite as broad as the seed and only very slightly longer. The relatively small
wing surface causes the rate of fall to be fast — the maximum distance for dispersal from 150' height has
been shown to be 400'. The seeds germinate in the fall in coastal areas, in early spring in the Rockies.
Seeds grow readily with about 70% germination rate when sown in spring in sandy soil in a temperature
of about 55°. The seedlings should be transplanted to open ground with partial shade. In nature there is
heavy early loss of seedlings from fungi, birds and insects followed by loss from drought. Therefore some
care is necessary.
Cuttings of the current season's growth about 2" — 3" long may be rooted in the greenhouse under light
mist in midwinter or in sandy soil in a cold frame in September. This method is the only means of
propagating cultivars.
Vegetative reproduction by adventitious roots from low-hanging limbs, trunks of fallen living trees or
from living branches that fall onto wet soil can occur. However, subsequent growth is very slow.
Transplants easily with a ball of soil around the roots, September to November or February to April.
Conditions for Cultivation
The growth rate is slow — under the most favourable conditions (in the Puget Sound area) the maximum
rate is 2.3 feet per year between the ages of 10 and 20 years declining to 0.61 feet per year after 60 years.
Diameters of 2 — 4 feet are reached in 200 — 500 years, some of the largest trees on record are believed to
be 800 - 1000 years old. The recommended hardiness zone for Thuja plicata in Canada is 6b (Sherk &
Buckley 1968). Although the species is very tolerant of shade it grows best in full sun or partial shade. The
soil should be deep moist well-drained loam. The nutritional requirements are very high — a rich supply of
base saturated water, calcium, magnesium and nitrates. If using as a hedge, plant in a 3 foot wide trench
about 3 feet apart in September, October, March or April. Training and pruning is best done between May
and July inclusive.
Landscape Value
Free standing trees provide moderate shade and are most valuable for specimen trees on lawns, banks
and margins of water, or for hedges. Dwarf forms are suitable for rock gardens. If grown in an open
situation the dense compact foliage is retained to the ground throughout life giving a very attractive
appearance. Trees are fairly resistant to wind when grown on dryish soil but on very wet soils the shallow
root system makes them subject to windthrow. They lend themselves readily to trimming and shaping.
This species and some of its cultivars are readily available in British Columbia from Lower Mainland and
Vancouver Island nurseries.
Ornamental Cultivars
Trees from inland sources are hardier than those from the coast, with greater frost resistance, and have
lustrous dark green foliage which turns a delightful bronze in the fall. A number of cultivars'have been
developed in Europe although several of these are now either very rare or lost to cultivation, den Ouden
(1965) lists 12 cultivars which are still available including cv. 'atrovirens' with shining dark green leaves and
such dwarf forms as cv. 'Rogersii' (a pyramidal golden yellow form), and cv. 'Cuprea' (a conical and very
slow growing form) as well as forms such as cv. 'Stoneham Gold' (a large bush with gold coloured leaves)
and cv. 'Zebrina' (a pyramidal tree with the foliage golden zebra striped although the variegation and colour
varies on the same tree).
43 44
Other Uses
Because of its resistance to decay, warping or shrinking and because it works easily Thuja plicata is used
in situations favourable to decay, e.g., for shingles, lumber, posts, pilings, boats, pattern stock, laundry
machinery, cigar boxes, greenhouse framework, house exteriors, etc. Paints, varnishes and lacquers adhere
well and it glues readily. In the areas of its natural occurrence it forms one of the important timber trees.
The Indians of the Pacific Northwest used the Western Red Cedar for their totem poles, war canoes and
lodges, bark from young trees for mats, baskets, rope, fishing line and even thatch for the lodges.
Diseases and other problems of cultivation
The thin bark and shallow roots make Thuja plicata very susceptible to fire. The foliage is easily
windburned late in winter if planted in exposed situations. Winter damage to young trees is serious
particularly when severe cold waves follow mild weather, therefore some protection is advisable for these.
Otherwise the species has few insects or other enemies. Fungi and viruses may cause root and trunk rots but
in most cases they only invade already weakened trees. Cedar flagging is a term which has been given to the
natural dieback of the tree, the dead red brown foliage falls during autumn and winter storms. This may be
much more noticeable in some years because it occurs earlier or over a short period of time, and there is a
suggestion that it is caused by a hot summer (H.N.W. Toms, personal communication).
Argyresthia sp. - 'leaf miner' or 'tip moth', is the larva of a tiny gray moth which feeds within the leaves
causing the leaf-tips to turn brown. This is not serious on T. plicata, but it is a good idea to trim and burn
all infected leaves as other species of ornamental trees are much more susceptible and there is always the
danger of cross infection.
Didymascella (Keithia) thujina — 'leaf blight' is very serious in some years on seedlings and young trees.
It is believed to be favoured by high humidity and may be fostered by a late spring snow cover.
Poria sericeo-mollis 'trunk rot' and P. weirii 'root and butt rot' cause some damage.
Armillaria mellea — 'honey mushroom' is often found around the base of the tree.
Origin of the name
The generic name is derived from an ancient greek work thuia for an aromatic evergreen tree the wood
of which was highly prized for choice durable furniture, but which is now believed to have been a juniper.
The specific name plicata means plicate or folded into plaits, and was perhaps suggested by the regularly
arranged scalelike leaves. The general term Arborvitae means the "tree of life" and was a name first given to
Thuja occidentalis. Survivors of Jacques Cartier's expedition to Canada in the early 16th Century were
apparently saved from scurvy by a decoction made by Indians from the branches. Subsequently the King of
France named it "l'arbre de vie" (arborvitae). Thuja plicata was named from a specimen at Nootka Sound.
Collingwood, G.H. & Warren D. Brush. 1962. Knowing Your Trees. 1955 Edition. The American Forestry Association,
Washington, B.C.
Hitchcock, C.L. et al. 1969. Vascular Plants of the Pacific Northwest. Part I. Vascular Crytogams, Gymnosperms and
Monocotyledons. Univ. of Washington Press, Seattle and London.
Hosie, R.C. 1969. The Native Trees of Canada. 7th ed. revised. Canadian Forestry Service, Department of Fisheries and
Forestry. Queen's Printer (Information Canada), Ottawa.
Krajina, V.J. 1969. Ecology of Forest Trees in British Columbia. Ecology of Western North America 2(1): 1-47.
den Ouden, P. 1965. Manual of Cultivated Conifers. Martinus Nijhoff, The Hague.
Pirone, P.P. 1970. Diseases and Pests of Ornamental Plants. 4th ed. Ronald Press Company, New York.
Sherk, Lawrence A. & Arthur R. Buckley. 1968. Ornamental Shrubs for Canada. Research Branch, Canada Department of
Agriculture. Publication 1286. Queen's Printer, Ottawa.
Silvics of Forest Trees of the United States. 1965. USDA Agriculture Handbook No. 271.
Sudworth, G.B. 1908. Forest Trees of the Pacific Slope. 1967. republication by Dover Publications Inc., New York.
Westcott, Cynthia. 1946. The Gardener's Bug Book: 1,000 Garden Pests and How to Control Them. The American Garden
Guild and Doubleday and Company, Inc., New York. Botanical Garden News and Notes
Seed Exchange Program 1971 - During the 1971 season 7,793 packets of seed were distributed to some
325 institutions throughout the world. The greatest demand was for native seed particularly those of the
conifers growing in the Lower Mainland or southwest region of British Columbia. The 1971 Index Seminum
has now been distributed to nearly 500 institutions. This year's seed list lists some 478 species and varieties
representing 70 families. A special section was added this year to accommodate the research grass collection
that has been developed by Dr. J.R. Maze of the Department of Botany.
Gardening though the Seasons — During the months of February and March the staff of the Botanical
Garden are offering two instructional programs under the auspices of the Centre for Continuing Education
at the University. The first course will cover the basic principles of propagation, planting and the growing of
flowers, fruit and vegetables through the spring and summer months. It is designed as a home owners'
course. The second program will be concerned with gardening for apartment dwellers.
Nitobe Memorial Garden 1971 - This garden continued to be a focal point of public interest at the
University and 92,706 visitors were recorded during the summer months. A large number of school children
and hospital groups took time to visit the garden. The Vancouver Ikebana Society provided weekly exhibits
of floral arrangements for the tea house.
Staff activities - Members of the staff continued to be active in various horticultural and professional
societies during the past year. Mr. Ken Wilson was elected President of the Vancouver Rose Society. Mr.
David Tarrant was elected Vice President of the Vancouver Orchid Society and Mr. Jim O'Friel continued
as a Director of the Alpine Garden Club of British Columbia. Dr. Roy L. Taylor was elected Director of The
American Association of Botanical Gardens and Arboreta. A Plant Improvement Committee was established
late in 1970 to develop a program to improve the overall quality of ornamental nursery stock being grown
in British Columbia. A five member committee was established with Dr. John W. Neill and Mr. Ken Wilson
of the U.B.C. Botanical Garden serving on the committee. The first action of this committee has resulted in
establishment of a program to review and propagate virus free stock of flowering cherries.
Climatological Summary  for  1971
The weather pattern in 1971 was generally cooler and drier with slightly less sunshine (1775.3 total
hours) than the ten year average. Temperatures range from a high of 84°F in July to a low of 13°F in
January and December, with the March maximum and minimum temperatures the lowest in the past
decade. Yearly rainfall at 41.52" was below the average while the total snowfall at 99.35" was more than
double the previous highest recorded total. An 11" snowfall on February 26th was the greatest amount
recorded in any twenty-four hour period in the past ten years. We are currently looking into the possibility
of obtaining additional wind data which might provide more meaningful information for horticultural use
than the present "mean mileage" figures.
Mean temperature
Highest temperature
50° F
Lowest temperature
28° F
Grass minimum temperature
Total rainfall/No. days with rainfall
Total snowfall/No. days with snowfall
Total hours bright sunshine/possible
Mean mileage of wind at 3'
Mean mileage of wind at 40'
*Site: The University of British Columbia, Vancouver, B.C., Canada.
Position: lot. 49°15'29"N; long. 123°14'58"W. Elevation: 342.6'. Juncus acuminatus, a tall rush of wet
places in southwestern British Columbia
/      //
Volume 2        Number 4        Winter 1971
Vines and Climbers at UBC 37
Thuja plicata Western Red Cedar 41
Botanical Garden News and Notes 45
Climatological Summary for 1971 45


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