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Davidsonia Sep 1, 1976

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 DAVIDSONIA
VOLUME 7
NUMBER 3
Fall 1976 Cover:
A    desert    hillside   dotted    with    Saguaro
(Carnegiea gigantea), chollas and prickly-
pears {Opuntia spp.), and Ocotillo
{Fouquieria splendens).
Opuntia engelmannii, Engelmann's Prickly-
pear. This cactus is common in northern
Mexico and the southwestern United States,
and is sometimes a pest on cattle ranges.
DAVIDSONIA
VOLUME 7
NUMBER 3
Fall 1976
Davidsonia is published quarterly by The Botanical Garden of The University of British
Columbia, Vancouver, British Columbia, Canada V6T 1W5. Annual subscription, six dollars.
Single numbers, one dollar and fifty cents. All editorial matters or information concerning
subscriptions should be addressed to The Director of The Botanical Garden.
Acknowledgements
The pen and ink illustrations are by Mrs. Lesley Bohm. The photographs on pages 38-42
and the inside back cover are by Dr. Roy L. Taylor, and those on pages 26-30 are by
Ms. Geraldine Guppy. The article on Acer circinatum was researched by Mrs. Sylvia
Taylor. Ms. Geraldine Guppy and Mrs. Jean Marchant assisted with layout and editing.
ISSN 0045-9739 Cacti and Succulents from Mexico
MARGARET COXON
The major part of the xerophyte collection at the U.B.C. Botanical Garden was donated by
Mr. and Mrs. C. Brown of Vancouver, and is the result of numerous collecting trips to Mexico as
well as many years of devoted care and maintenance. An assortment of cacti and succulents from
this special collection is presented here. Since these plants derive much of their interest from their
unusual growth form, a number of the rarer and more distinctive members of the cactus family
have been included.
The plants found in the dry deserts of Mexico display a fascinating assortment of life forms.
These desert plants all face the common problem of a dry, hot and windy climate, and they have
overcome this problem in various ways. Among the best-known of desert plants are the cacti and
succulents, which have adapted to their native regions by developing thickened stems or leaves for
storing water. These plants do well in the dry sunny plateaus of Mexico, and show remarkable
tolerance of the harsh growing conditions. The conditions vary from one part of the country to
another, and for each species whose range is known, the provinces in which it grows are mentioned here.
Cacti are a unique group of plants with thick, often jointed stems and no leaves. Most of them
have spines. Their flowers, though usually short-lived, are often large and showy. The cactus
family is native to the New World, and in Mexico there are more than 700 native species of
cactus — a larger number than in any other part of the Western Hemisphere.
Mexico also has a wealth of plant species which, though not members of the cactus family,
resemble these plants in many ways and often live in similar habitats. These are the succulents,
and they belong to a number of different plant families (including the lily, stonecrop, aster and
milkweed families).
Hobby growing of xerophytes (desert plants) is fast becoming a very popular pursuit. Growing
these plants in cultivation is not difficult, but there are a number of factors that must be considered. Most cacti and succulents need good light for healthy growth, and particularly for
flowering. Summer conditions, during the growing season, should be bright and hot; winter conditions should be bright but cool. Many cacti can tolerate quite low temperatures during the
winter, and a few are frost-hardy. Once a few basic rules are learned, these plants require relatively little attention.
Soil for both cacti and succulents should be rich but loose and well-drained, with plenty of
sand or gravel mixed in. In general, the white or very hairy cactus species prefer a soil high in
calcium. Plant them in clay pots for best drainage and air circulation.
Xerophytes should be watered regularly but the soil should be allowed to dry out between
waterings. Standing water or waterlogged soils will cause rot. Succulents need more water than
most cacti. During the winter, when temperatures are cooler and the plants are experiencing a lull
in growth, they should be watered sparingly. The plants should be washed occasionally during the
growing season with a heavy mist. Cacti
A species which is a favorite with many
people is Astrophytum myriostigma, commonly known as the Bishop's Cap. It grows on the
open mesa of the north-central region of
Mexico, in the provinces of Coahuila and San
Luis Potosi. This cactus lacks spines and is gray
and stonelike in appearance, with usually five
broad ribs. Its surface is covered with fine white
flecks and there are circular woolly markings
along the ridges. The plant may grow to 60 cm
high and 20 cm across. The flowers are large
and light yellow, with red centres, and appear
all summer; they are followed by star-shaped
fruits. The Bishop's Cap prefers a hot climate
and a soil high in calcium. It does indeed
resemble a bishop's cap, and it has also been
likened to the Sydney Opera House in Sydney,
Australia, which has the same distinctive shape.
FIGURE I. Astrophytum myriostigma, the Bishop's Cap.
FIGURE 2. Echinofossulocactus zacatecasensis, the Brain Cactus.
equally as broad. It has approximately 20 ribs
covered with thick, sturdy spines. In each tuft
of spines is a central spine that is broader and
flatter than the others, and curved at the tip.
The color of the spines varies greatly, from
reddish when young to yellowish with increasing age. In many species they have distinct
crosswise rings or bands of color. The flowers
of this cactus are reddish in color and are sweet-
scented. This species prefers a temperate
climate. Another barrel cactus, Ferocactus
covillei, has attractively marked reddish spines
which are often sharply hooked. It makes an
equally good pot plant.
Some cactus species have evolved amazing
camouflages to protect them from grazing
herbivores. Ariocarpus trigonus, often called
the Living Rock, is found in the northeastern
part of Mexico (the provinces of Coahuila,
Nuevo Leon and Tamaulipas). This cactus
closely resembles the stony desert on which it
Another cactus of strange appearance is the
Brain Cactus, Echinofossulocactus zacatecasensis, also from north-central Mexico (the
province of Zacatecas). It is a low-growing
species, forming a disk which may reach 10 cm
in diameter. It is deep green in color, with
numerous narrow ribs closely compressed and
folded together. The spines are scattered
sparsely over the plant in inconspicuous tufts.
The flowers are white, tipped with lavender,
and appear freely throughout the spring.
The barrel cacti have a distinctive round
shape, and strong, sharp spines of many
different forms and arrangements. Ferocactus
latispinus, a barrel cactus from central and
eastern Mexico,  grows to 40 cm  high  and
FIGURE 3. One of the barrel cacti, Ferocactus latispinus. grows. It forms a flat, inconspicuous mound
dotted with tubercles, supported by a thick,
massive tap root. The flowers are yellow, and
appear in November. All species of Ariocarpus
are poisonous and have been used as medicine.
Another small cactus of prostrate growth
form is Obregonia denegrii, the Artichoke
Cactus. It is found in the province of
Tamaulipas and prefers a temperate climate.
Like Ariocarpus, it is flattened, greyish-green
in color and covered with tubercles. The tubercles, which are arranged spirally, point inwards
like the leaves of an artichoke head. The
flowers appear in the centre of the plant and are
white in color, and the seeds which later follow
them are large and black.
FIGURE 5 (above). Ariocarpus trigonus, the Living Rock.
FIGURE 6 (below). Obregonia denegrii, the Artichoke Cactus.
Strombocactus disciformis is found in
Central Mexico, in the province of Hidalgo.
This tiny cactus has a gray-green body with
spirally arranged ribs divided into low tubercles. In size and shape, it has a marked resemblance to a pine cone. Near the centre of the
crown are a few clusters of spines, through
which the flowers appear. The flowers are white
tinged with red and yellow, and are followed by
brown seeds. Strombocactus does well in a soil
high in calcium.
Leuchtenbergia principis, a cactus from
northern Mexico, grows amongst grasses and
agaves and does not look at all like a cactus. It
is an interesting plant which grows to about
15 cm in width and forms a rosette of triangular
leaflike tubercles. The tubercles are blue-green
FIGURE 4. The barrel cactus Ferocactus covillei, a species which occurs in
Arizona and in northern Mexico.
in color and have clusters of papery spines on
the tips. The flowers are pale yellow, large and
long-lasting. This plant has a well-developed
tap root and does best in a rich soil.
The Opuntias, which are among the best-
known of all cacti, make up a large group that
includes the prickly pears, the bunny ears, and
the beaver tails. These plants have stems in
jointed sections, the individual sections often
being flattened and leaflike in shape. In North
FIGURE 7. Strombocactus disciformis. This specimen is about 4 cm across.
27 3$
{my*-
28
and South America, Opuntias have been used
to make impenetrable fences and have also been
used as a food source. In Australia, however,
they have become a nuisance in the interior of
the continent, where they have spread unchecked by natural predators. These cacti
propagate very readily from the individual
stem sections.
Opuntia rufida, the Cinnamon Cactus from
northern Mexico, grows to 1.5 m tall. It has a
treelike form, with many branches extending
from a single main trunk. Like other members
of this group, it bears small bristles called glo-
chids in addition to the spines. These bristles
are rusty-brown in this species, hence the
common name. If touched they embed themselves in the skin, and are irritating and difficult
to remove.
Another member of this group is the Beaver
Tail, Opuntia basilaris, from northern Mexico.
The stems of this species often creep along the
soil. The flattened stem sections or "pads" may
reach 20 cm in length. The plant is a beautiful
bluish color, with coppery-colored spines. In
the summer, attractive purplish flowers appear.
Carnegiea gigantea, the Saguaro, grows in
northwestern Mexico (the Sonora region) and
adjacent parts of the United States. It is a
monster of the cactus world, and is tree-like
both in size and in silhouette. The "skeleton"
or woody portion of the stem has actually been
used as a building material, and is often made
into lamps and other novelties. The flowers are
large, white and nocturnal, appearing on the
ends of the long stems. They are followed by
juicy red fruits. The Saguaro is the state flower
of Arizona.
A marked contrast to the huge Saguaro is
the tiny soft Mammillaria plumosa from
northern Mexico. This tiny cactus grows clustered together in rock clefts, and it is so densely
covered in soft feathery spines that the pale
tubercles are scarcely visible. It produces small
white flowers, which are inconspicuous against
the white of the "feathers". This species is only
one of many kinds of Mammillaria. The genus
is a large one, and is widespread in Mexico.
FIGURE 8. A handsome example of Carnegiea gigantea (the Saguaro), with
Fouquieria sptendens (Ocotillo) growing at its base. FIGURE 9 (right). Leuchtenbergia principis, one of the most unusual-looking
Mexican cacti. The spines are borne on the ends of the leaflike tubercles.
FIGURE 10 (left). Mammillaria plumosa. This specimen has been grafted onto
another cactus species; normally it forms low ground-hugging clusters.
FIGURE 11. Opuntia rufida, the Cinnamon Cactus, lacks the long spines found
in most members of the Opuntia group. Another favorite of collectors is Echino-
cereus dasyacanthus, the Rainbow Cactus, from
northeastern Mexico. It is called the Rainbow
Cactus because of its multicolored spines, which
are short and stiff and arranged in bands. Their
color varies with the seasons, but regrettably
are less striking in cultivation than in the plant's
native habitat. The flowers are also very beautiful — large and bright pink. Echinocereus is
usually barrel-like in shape, but occasionally
forms branches.
FIGURE 12. Echinocereus dasyacanthus. the Rainbow Cactus.
The Cephalocereus senilis or Old Man
Cactus from central Mexico (Guanajuato,
Hidalgo and Puebla) is a most interesting
species. Its name is derived from the fine white
hairs which clothe the slender columnar stems.
It may become very large in nature, growing to
10 or 12 m tall in its native hills and valleys.
This plant may live for years before producing
its nocturnal pink blooms, but its attractive
habit of growth makes it well worth while as a
cultivated plant.
Succulents
One family which includes many Mexican
succulents is the Agavaceae. Agave victoria-
reginae is the Queen Agave from northern
Mexico. It is a stunning plant, with a low
rosette of swordlike, unusually marked leaves.
The leaves grow to a length of 15 cm and are
deep green in color with white margins and
horny tips. This plant is very slow-growing and
takes many years to produce the 5 metre high
inflorescence with its green blossoms. Once it
has bloomed, the plant then dies.
FIGURE 13. Agave victoria-reginae, one of the most attractive members of
its group,
Agave stricta, found near Tehuacan in the
province of Puebla, is a round dense hedgehog
of an Agave. It has slender and very sharp
leaves, and is a beautiful plant, growing to a
maximum of 40 cm high. The leaves are attractively marked, with grey stripes on the margins.
FIGURE 14. Agave stricta, a striking slender-leaved species. A more delicate and less drought-resistant
plant is the favorite Sedum morganianum, the
Donkey's Tail from the eastern coastal province
of Vera Cruz. This plant belongs to the Crassu-
laceae or stonecrop family. Its trailing branches
reach a length of 1 metre and are covered with
pale green fleshy leaves up to 2.5 cm long. It
makes an excellent hanging plant. The blossoms
are red, and appear on the ends of the "tails".
Pachyphytum bracteosum is another attractive succulent and is also a member of the
stonecrop family. It is grey-green in color, with
thick smooth leaves which form an upright
rosette. The brilliant red blossoms appear on
long upright stems during the summer months.
I IGLIRE 15  A flowering stem of Pachyphytum bracteosum.
FIGURE  16. Echeveria gibbiflora, the Donkey\ Ear,  has large handsome
rosettes of blittsh-colorcd leaves.
The genus Echeveria was named after a
Mexican botanical artist. It contains 60 or more
species, most of them native to Mexico.
Echeveria gibbiflora, the Donkey's Ear (from
the large flat leaves), is found in central Mexico
near Orizaba and Cuernavaca. It is the largest
member of the genus, producing a large rosette
of leaves up to 35 cm across. The main stem
may grow to more than a metre in length. The
leaves are up to 18 cm long and 10 cm wide, as
many as 20 per rosette, and vary in color from
bluish-green through rose and violet, or even
bright red when temperatures are low. The
flowers are coral red, partly concealed by the
violet-gray sepals. They are borne in late fall or
winter on flower stalks up to a metre long. Acer circinatum Pursh
VINE MAPLE
Member of the Family Aceraceae
Natural Distribution
Acer circinatum occurs from British Columbia south to northern California. It is most common
west of the Cascade Mountains, but also occurs east of the Cascades (for example, in the Wallowa
Mountains of northeastern Oregon). In British Columbia the species is found from sea level to elevations of 900(-1050)m in the coastal forest, as far north as Knight Inlet (51°N) and as far inland as
Manning Provincial Park. It is also recorded from Wells Gray Park, 150 miles north of Kamloops. It
is probable that there are other occurrences of this tree in the wetter parts of the Interior. On Vancouver Island it is known to occur naturally along the Robertson River (near Cowichan Lake) and the
Salmon River (north of Campbell River).
Habitat
Acer circinatum is characteristically found along moist stream banks and in damp woods and
meadows, in moist, rich, rocky soils. It may grow in thickets or scattered among other species. It is
extremely tolerant of dense shade, and often forms a constituent of the coastal forest understory.
It also occurs in forest openings, especially on recently logged-over areas. In British Columbia the
species is an edaphic climax shrub in both the Coastal Western Hemlock and Coastal Douglas-fir
Zones. The climate in areas where it occurs is characterized as marine subhumid to humid or rainy,
with warm dry summers, a mean annual temperature of 5°-ll°C, absolute minimum and absolute
maximum temperatures of -30° and 41 °C respectively, and an annual total precipitation of 66 to
665 cm (Krajina 1969).
Description
The species is an erect to reclining or vinelike, usually several-stemmed, deciduous shrub or small
tree, 1-10(-15) m tall with a DBH of 7-20(-30) cm. When growing as a shrub, it has an irregular broad
open crown with slender, crooked or crumpled branches; the stems are several to many from the base,
weak and slender, very twisted, glabrous or sparsely pilose to almost glaucous, and reddish-brown or
light green, becoming brown with age. When growing as a tree, it has a round-headed open crown
and a single short crooked trunk which is often prostrate or arching with a few twisted spreading
limbs. In dense shade the stems are particularly long and twisted, producing a straggly crooked form,
whereas open-grown specimens are apt to be shorter, more compact, and more erect and symmetrical.
Dense thickets are often formed due to the vine maple's habit of layering by low-lying branches. The
species reaches its largest size on the rich alluvial soil of bottom lands, where it may have 4 or 5 vinelike stems spreading in wide curves and sending out long slender branches. It is much smaller in the
southern part of its range.
The root system is fibrous and vigorous. D X  1.0
C   X 4.0
B  X  1.0
3.0m r
2.5
2.0
1.5
1.0
0.5
E  X  5.0
0.5        1.0       1.5        2.0       2.5        3.0       3.5        4.0        4.5m
FIGURE 17. Acer circinatum. A. habit of tree, B. twig with mature fruits, C. a single female flower,
D. twig with flower cluster and newly unfolded leaves, E. a single male flower. The bark is astringent, thin, smooth or with many shallow fissures (especially near the bases of the
larger trunks), greenish at first, but later becoming bright reddish-brown or dull grayish-brown
tinged with red.
The twigs are slender, much branched, smooth, glossy red and often covered with a glaucous
bloom when young, later becoming greenish-red to red-brown and glabrous. They are very contorted
and irregular in shape, occasionally ribbed below the leaf scars, slightly gummy, and almost round to
somewhat 6-sided in cross section. The sap is clear and somewhat sweet. The pith is pale, round to
slightly angled, and continuous.
The wood is very hard and fine-grained, tough but low in strength. It is dense and surprisingly
heavy, but checks badly on drying and rots quickly when in contact with the soil. The heartwood is
very pale brown to almost white, the sapwood thick and lighter-colored.
The buds are opposite, 3 mm long, solitary or sometimes collaterally multiple, ovoid or conical,
obtuse, and subtended by a fringe of long white hairs from the upper margin of the leaf scar.
Terminal buds are generally lacking (except for flower buds), but the topmost lateral bud on each
twig is enlarged and appears terminal. The lower laterals are much smaller. The outer scales are
usually 4 in number, opposite, rounded on the back, thin, shiny, bright-red and sometimes green at
the base, and glabrous, with white-ciliate margins and a tuft of long hairs at the tip. The inner scales
along the veins on the upper surface. They are conspicuously palmately nerved with prominent vein-
lets, and are exstipulate. The petiole is 2-4(-5)cm long, stout, grooved, puberulous at first but later
becoming smooth, and clasping the stem by a large base.
The leaf scars are small, opposite, sometimes ciliate, more or less U- or V-shaped, and narrowly
linear at the base of the season's growth, becoming broader towards the tip. The bundle traces are
3 in number (rarely 5-7), and stipule scars are lacking.
The leaves are opposite, simple, orbicular, thin and membranaceous, (3-)5-15(-18)cm long and
(4-)5-12(-15) cm broad, and palmately lobed almost to the centre. The bases of the leaves are cordate
with a broad and usually shallow sinus, or sometimes almost truncate. The lobes are (5-)7-9(-l 1) in
number, the apices of the lobes acute to acuminate, narrowly triangular and separated by V-shaped
notches. The leaf margins are irregularly and sharply singly or doubly serrate. The leaves are rose-red
or with reddish tints when young, later becoming bright green or bright yellowish-green above and
paler below, and eventually turning reddish-yellow to orange and scarlet in the fall. They have the
most vivid coloration of any coastal tree or shrub. The leaves are villous when young, becoming
glabrate in age except for tufts of hairs near the base, in the angles of the veins beneath, or sometimes
along the veins on the upper surface. They are conspicuously palmately nerved with prominent veinlets,
and are exstipulate. The petiole is 2-4(-5) cm long, stout, grooved, puberulous at first but later becoming smooth, and clasping the stem by a large base.
The flowers are produced from March to June, depending on the range. They appear with the
leaves or when the leaves are about half grown. The inflorescence is a drooping terminal loose
corymb, on slender 2-leaved lateral branchlets, usually 4-10(-20)-flowered. The pedicels are long and
slender, and branch frequently. The flowers are 6-9 mm across, regular, and polygamous (with intermingled perfect and unisexual flowers), but only one sex is functional in each flower. Most of the
flowers are staminate. The calyx is (3)4-6 mm long, dark red to purplish, and villous to sparsely pilose
near the tip; the calyx lobes are (4)5, imbricated, oblong to obovate, acute and spreading. The petals
are (4)5, white to greenish-white, and cordate with an acute, hooded apex; they are shorter than the
calyx. The stamens are (4-6-)7-8(-10-12) in number, the filaments slender and villous towards the base.
The stamens are inserted on the inner edge of the fleshy annular disc, and are exserted and fertile in
staminate flowers, short and abortive in perfect ones. The styles and stigmas are 2 per flower, the
styles slender, connate only at the base and inserted between the lobes of the ovary. The ovary is
superior, compressed and glabrous, with 2 spreading lobes each of which contains 2 ovules. After
fertilization an elongate divergent wing rapidly develops from each carpel. In staminate flowers the
ovary is reduced to a small point surrounded by a tuft of small hairs. The fruit is a double, winged samara 2-3.5(-5) cm across, glabrous or sparsely pilose, compressed,
ridged, and usually separating just before falling. The wings are at an angle of almost 180° from each
other and at nearly 90° to the pedicel; they are obovate, up to 4 cm long and 0.9 cm broad, thin, but
with a thickened area on the lower margin. The nutlets and wings are rose-colored to tawny when
mature. The fruit matures in late autumn, by which time the pedicels have turned upright so that the
samaras stand erect above the leaves. The seeds are usually one per samara (the other one aborting),
but occasionally two. They are smooth, 0.3-0.6 cm long, pale chestnut-brown, ovoid, compressed
and irregularly 3-angled. The seedcoat is membranaceous, the inner coat often fleshy. The species is
only a moderate periodic seeder, although some seed is borne locally every year.
Propagation
Vine maples should be propagated by seed whenever possible. Seeds should be sown soon after
maturity, or stratified at 5°C and sown in the spring. They soon lose their ability to germinate, and
should not be allowed to dry out. The seedlings require partial shade during development.
Cuttings from half-ripened greenwood may be taken in summer.
Although vegetative propagation by rooting of low-lying branches is common in nature, particularly if the branches are covered by moss or leaf mould, layers in the nursery may take more than a
single season to root.
Varieties and rare forms may be budded in summer onto the species.
Transplantation
Transplantation of this species is relatively easy, because of the fibrous nature of the roots and the
absence of a well-developed taproot. Provided that the operation is carried out while they are dormant, fairly large specimens can be moved successfully.
Conditions for Cultivation 35
The species is a very persistent but slow grower, taking many years to reach full size. It has been
estimated that a tree with 10 to 12.7 cm DBH was 60-70 years old. The longevity of the species has not
been determined with certainty, but 80 to 90 years may be the maximum. The recommended hardiness zone in Canada is Zone 6 (Sherk & Buckley 1968). Acer circinatum is easily grown under almost
all conditions of soil and moisture, but prefers good moist well-drained soil and a climate with high
precipitation and high relative humidity. It is tolerant of fairly dense shade, where it develops the
contorted shape so characteristic of wild specimens, but will also grow well in a relatively sunny position. Specimens should be sheltered from cold winds and are prone to damage from late frosts. Very
little pruning is required, except that which is required for training purposes. The lower branches may
be pruned from a tree form as it grows in height, until sufficient clear stem has formed. As with all
maples, pruning should be done during the late summer or early fall or during the fully dormant
period, but never in spring because the fast-rising sap leads to severe "bleeding" from the cut
surfaces.
Landscape Value
The genus Acer as a whole is of great ornamental value. Acer circinatum is of considerable value
in the garden, particularly in its native area, because it has something of interest in every season. In
spring the flowers with their purplish sepals and whitish petals are very attractive, especially when
associated with the conspicuous crimson bud scales. In summer the leaves are prettily tinted, and
form an interesting delicate pattern with the winged rose-colored fruits. In fall there is the beautiful
brilliant orange and scarlet coloration, and in winter the contorted and twisted branches make an
attractive silhouette. The species is well adapted for use in gardens because of its small compact size
and ability to grow in partially shaded situations, especially under large conifers in a woodland
planting. Vine maples may be planted around small garden ponds and pools, as long as these are
completely watertight so that the soil is not waterlogged. These trees may also be espaliered against a 36
wall, or even grown in a large container (35 cm or up) on a patio. Vine maple is better planted in small
groups than as a single specimen; the multiple trunks then give the impression of a grove of trees.
When grown in the open as a single specimen, it tends to lose its vinelike characteristics and becomes
more erect and open. This tree casts moderately dense shade, and the root system, while quite energetic, is not invasive.
Availability
The shrub is readily obtainable from nurseries in the Lower Mainland area of British Columbia.
Varieties and Ornamental Cultivars
No varieties of Acer circinatum are recognized. In 1915, J. K. Henry described (from a specimen
in Stanley Park, Vancouver) var. fulva, with yellowish twigs and sepals and the petals not so cucul-
lately pointed as in the species. However, this doubtful variety is no longer accepted.
One cultivar, 'Elegant', has been selected and named at Ottawa.
Other Uses
The wood is of little commercial value because of its small size, crooked form and weakness, but
it is used locally for fuel and for minor domestic purposes such as making tool handles. Woodsmen
use green vine maple for pothooks and campfire reflectors, because it is almost impossible to burn.
Because of the layering habit of the branches, the shrub may be of some use in reclamation projects.
Livestock may also browse this species. Various people have experimented with making maple syrup
from the sap, with limited success.
The Cowichan, Salish and Squamish Indians of British Columbia used the wood to make knitting
needles, but it was not considered ideal because the wood warps over a period of time. Spoons, bowls,
platters and other small household items were carved out of the wood. The Quinault Indians of
Western Washington used to refer to the species as the "basket tree". The long straight shoots were
used to make an openwork basket, either with a crossed-warp twine or with a broad-spaced checkerboard weave, which was then used for general household purposes such as carrying wood, clams or
fish. The same tribe also used poles of vine maple to hold down the roof planks on their houses, and
mixed the charcoal with oil to make a black paint. The Skagit tribe used saplings for salmon tongs,
and as swings for babies' cradles. Several Washington tribes used vine maple to make fish hooks or
wattleworks for fish traps, because of its toughness.
Diseases and Problems of Cultivation
It has been reported that the hairs on the samaras may be irritating to some people, especially
nurserymen handling them in large quantities.
Several fungi occasionally attack maple leaves but most do little damage. Toms (1964) reports
Oidium sp. (a powdery mildew) from the Vancouver area, and Phleospora aceris (Lib.) Sacc. (a leaf
spot) from the Lower Fraser Valley. Coral spot, a fungus causing orange pustules on infected wood,
may cause considerable damage. It initially attacks dead wood but then spreads to living branches,
especially if the specimen is in poor health. It causes dieback of branches and may even kill the entire
tree. All dead and diseased wood should be cut out and burnt, and all cut surfaces sealed.
Several insects, including Pulvinaria innumerabilis (cottony maple scale), Hemerocampa spp.
(tussock moths), and the defoliating moths Antheraea polyphemus Cram, (polyphemus moth) and
Pseudohazis eglanterina Bdv. may attack maples, including vine maple, but they usually do little
serious damage.
The shrub is susceptible to late frosts and should be sheltered from cold winds.
The generic name Acer is the classical Latin name for the maple tree. The word means 'sharp',
referring to the hardness of the wood, which the Romans used for spear hafts. It may also mean sharp or pungent, referring to taste as well as touch. The generic name circinatum may be derived
from the generally rounded or circular form of the leaves, but also means coiled or curled around like
a crook, and may therefore be a reference to the general shape of the branches. The common name
originates from the often sprawling, crooked, vinelike appearance and habit of the slender weak
stems. The word 'maple' derives from the Anglo Saxon word for maple, mapulder, which gave rise to
the Old English or Middle English mapel, mapul or mapil. Chaucer used the word maple in 'The
Romaunt of the Rose' before 1366 and it was in general use by the late 16th century. It is conjectured
that mapulder may be traced back to the Old High German word mazzaltra and possibly to matlu,
meaning food, the young leaves of A. campestre having been eaten as a pickle.
The type locality is 'on the great rapids of the Columbia River', where it was collected by Lewis. It
was introduced to cultivation in Great Britain by Douglas in 1826.
REFERENCES
Gilkey, H. M. & P. L. Packard. 1962. Winter Twigs. Oregon State Univ. Press, Corvallis.
Grigson, G. 1974. A Dictionary of English Plant Names (and Some Products of Plants). Allen Lane, London, England.
Gunther, E. 1945. Ethnobotany of Western Washington. Univ. Wash. Publ. Anthropol. 10(l):l-62.
Hitchcock, C. L. et al.  1961. Vascular Plants of the Pacific Northwest. Part 3. Saxifragaceae to Ericaceae. Univ. of
Washington Press, Seattle.
Hosie, R. C. 1969. 7th ed. rev. The Native Trees of Canada. Canadian Forestry Service, Department of Fisheries and Forestry.
Queen's Printer, Ottawa.
Hottes, A. C. 1942. The Book of Trees. A. T. DeLaMare Company Inc., New York.
Krajina, V. J. 1969. Ecology of Forest Trees in British Columbia. Ecology of Western North America 2(1): 1-147.
Lyons, C. P. 1965. Rev. ed. Trees, Shrubs, and Flowers to Know in British Columbia. J. M. Dent and Sons (Canada)
Ltd., Vancouver.
Mulligan, B. O. 1958. Maples cultivated in the United States and Canada. American Association of Botanical Gardens
and Arboreta, Lancaster, Pennsylvania.
Murray, A. E., Jr. 1970. A Monograph of the Aceraceae. Ph.D. Thesis, Pennsylvania State University.
Sherk, L. A. & A. R. Buckley. 1968. Ornamental Shrubs for Canada. Research Branch, Canada Department of Agriculture,
Publication 1286. Queen's Printer, Ottawa.
Smith, A. W. 1971. A Gardener's Dictionary of Plant Names. (Revised and'enlarged by W. T. Stearn.) Cassell, London.
Sudworth, G. B. 1908. Forest Trees of the Pacific Slope (republished 1967). Dover Publications Inc., New York.
Toms, H. N. W. 1964. Plant Diseases of Southern British Columbia. A Host Index. Reprinted from: Canadian Plant
Diseases Survey 44:143-225. Canada Department of Agriculture, Ottawa.
Turner, N. C. Squamish Plant Names. Unpublished typewritten manuscript.
37 Pool and Bridge Renovations in the Nitobe Memorial Garden
38
The Nitobe Memorial Garden, constructed in 1959 and opened in May 1960, has been a source of
pleasure and enjoyment for not only the faculty, staff and students at the University, but the many
thousands of visitors who have come to the Point Grey area during the past sixteen years. The original garden was designed by Professor K. Mori, the dean of Landscape Architecture in Japan at the
time. Professor Mori was well known for the Japanese gardens that he had designed and built in
many parts of the world and the Nitobe Memorial Garden at the University is the last garden that
Professor Mori designed and developed before his death.
The Garden is a classical stroll garden, and contains a small lake some 22,400 square feet in area.
The circulating water system in the garden contains approximately 500,000 gallons of water. Initially
the pool was lined with an asphalt-based membrane, and over the years this membrane has hardened
and showed some leakage. As a result it was decided in 1976 to renew the pool membrane. We felt it
useful to provide documented information about the construction and renovation of this new pool
membrane, as we often have enquiries from interested visitors and landscape architects as to how the
pool is maintained and developed. This article will provide detailed information for those who are
interested in the construction and waterproofing of pools.
Among the outstanding features of the Nitobe Memorial Garden are the stones which have been
placed throughout the garden, and in particular those which encircle the main garden pool. The rock
was selected from local sources in the Lower Mainland of British Columbia, and some of it came
from as far away as Britannia Beach and Harrison Lake. Professor Mori took great care in the
selection and placement of these stones, and one of the important considerations in the renovation of
the pool membrane was to retain the aesthetic lines of the pool. An initial survey was undertaken
after the pool was drained to determine how best the membrane could be replaced without destroying
these aesthetic qualities and yet provide the necessary waterproofing. After considering various
alternatives it was determined that a cement membrane would be the most permanent solution to the
problem, since no maintenance is needed.
FIGURE 18. A general view of the Nitobe
Garden main pool looking toward the island,
showing the appearance of the poo! surface
following the installation of the steel and wire
mesh grid, and the covering of the shrubbery
and decorative marginal stones. FIGURE 19 (right). A detailed view of the
steel and wire mesh grid placed on the pool
surface next to the stone decorative edge. The
masking tape on the stones indicates the
normal water level of the pool.
FIGURE 20 (left). Detail of the margin of the
pool prior to installation of the shotcrete,
showing how the surface of the rocks above
the water level was protected by the use of
plastic covering.
39
Basically, construction of the membrane consisted of the laying down of a wire mesh over the
entire bottom of the pool, followed by application of a cement mix over the wire mesh to form a
single complete surface. The shrubbery, lanterns, bridges and stones around the edges of the pool
were covered with 4 mil plastic to protect them from the spray from the concrete pouring process.
Our staff worked in consultation with the Department of Physical Plant to establish the strength
requirements for the pool membrane, and a formula for the cement mix was developed and approved
by the Department of Physical Plant. The cement mix was as follows for each unit:
600 lb Portland cement Type 1
500 lb fine sand
2100 lb coarse sand
700 lb aggregate 3/8" or less The program was initiated in the late fall when weather conditions were suitable for the cementing
work, and a total of 3 Vi working days were required by Pacific Shotcrete Installations Ltd. (Burnaby,
B.C.) for the application of the cement using the wet shotcrete system. Incorporated in the membrane
were three hydrostatic pressure release valves to prevent subterranean water accumulation, so that the
membrane would not be broken by pressure from below.
The procedure for the repair of the membrane was as follows: The pool was drained. The Koi
carp that are normally in the pool were removed to another suitable pool on campus. The pool was
cleaned and washed to provide a clean surface on which the cement would be laid. This was followed
by the installation of wire mesh consisting of 10/10 wire welded in 6 x 6 inch squares. A 6 inch overlap was made on all mesh section joints. This wire mesh was laid over a 3 foot square supporting grid
of #3 steel rods. Care was taken to ensure that the mesh went up to and around the stones forming the
border of the pool. Once this was completed, concrete was delivered by truck to the site, pumped into
the pool area, and sprayed onto the surface. The mix, known as shotcrete, was pumped wet from outside the garden through a 3 inch pipe to a 2Vi inch flexible pump hose which was used to apply the
shotcrete. The shotcrete was applied with a pressure of 1200 to 1800 lb per square inch, to a minimum
thickness of 3 inches over the pool bottom and sides. This layer is capable of withstanding pressures
of more than 500 lb per square inch after 28 days. Bridge pilings were wrapped with expansion joint
material to within an inch of the top of the shotcrete surface, so that a complete seal would be maintained. Special care was taken to ensure back filling of the shotcrete around the decorative stones of
the pool margin. Shotcrete was placed to 3 inches above the normal waterline of the pool (indicated
on the stones by masking tape). To complete the repair of the pool lining, 203 yards of shotcrete
were used.
Following completion of the cementing, the
whole membrane was washed down to remove
excess lime from the cement. The pool was
^4-0 filled,  then  drained  and  filled  again.   This
slushing action was necessary to hasten the
return of the water quality to normal. We have
estimated that a three month period is required
for the quality of the water to return to a level
which will allow the fish to be replaced in the
pool. No surface treatment of the cement
membrane was  used,   on  advice   from  the
FIGURE 21. A view of the channel between the east
side of the garden and the island, showing the problems
encountered in the protection of the shrubbery and the
bridge against the shotcrete treatment. In the foreground is the 3 inch pipe used to pump the shotcrete into
the garden area. FIGURE 22. A view of the work crew installing the concrete using the shotcrete system. The membrane is a minimum of three inches thick over the entire pool area.
41
FIGURE 23. An area in which the shotcrete has been completed along the upper margins of the pool. The lower portion of the pool was completed last. FIGURE 24. A completed portion of the pool,
showing the final shotcrete surface and the
plastic used in protecting the shrubbery and
pool margin.
Vancouver Public Aquarium and other groups dealing with the maintenance of fish in cement tanks.
The application of a surface treatment would in any case require maintenance on a continuing basis,
and such a program would add a nonessential maintenance cost. The total cost of the program was
approximately $27,000.
During construction of the new lining of the pool the bridges were also inspected, and new wooden
A 2 pilings and decking were installed. Structural members were pressure-treated (to 0.4 lb per cubic foot
retention) with Greensalt K33. This preservative treatment will help increase the life expectancy of
the bridge structures. New decking was installed on the main bridge, the waterfall bridge and the iris
pond bridge. The total cost of this replacement was approximately $7,500.
The new pool membrane is a permanent structure which will require essentially no maintenance in
the forseeable future. These repairs should also reduce the total amount of water required to maintain a satisfactory level in the pool. Some problems were encountered with excess spray of the concrete around the decorative stone margin, but this was much reduced by use of the plastic liner to protect the rocks. In some instances, removal of excess cement by chipping was required after the program was completed. Planting pockets along the margin of the pool have been replanted with new
plant material so that the original merging of the water with plants and stones can be achieved. The
program has been a satisfactory one from an aesthetic viewpoint, and we believe that similar programs could be used with success in pool construction projects in both home and public gardens. We
hope that these new improvements will provide reduced maintenance costs for a number of years,
while retaining the qualities of the original garden design. Botanical Garden News and Notes
Friends of the Garden Program — In the Spring of 1976 a new program, the Friends of the Garden
Program, was initiated at the Botanical Garden. The first class of the Friends of the Garden consisted
of ten people who participated in a training program to learn about the activities of the Garden. In
the Fall of 1976 an additional class was established and a similar training program initiated. Also
during the Fall a series of projects on specific program areas of public interest were begun by the
Friends of the Garden. These include the illustration and development of a new book for children on
the Nitobe Memorial Garden, the development of individual trail guides for trails in the B.C. Native
Garden, a study of plants suitable for inclusion in the Physick Garden section of the Main Garden,
the initiation of a program for the use of house plants as therapy for extended care patients in hospitals, the development of plants displays at the Garden and elsewhere on Campus, and the organization of an art exhibit by illustrators of B.C. plants (to take place in 1979). During the spring, summer
and early fall, the Friends of the Garden provided much-needed assistance for the many public tours
which visit the Garden, particularly those from hospital groups and public shcools. We anticipate
that the Friends of the Garden will be active in developing a tour program for these specialized education groups in 1977.
New Areas Completed — Four new Garden components have been completed under contract in the
Main Garden area. These are the Entrance Garden, the Physick Garden, the Arbor Garden and the
Contemporary Garden for the display of ornamental plant materials. Initial planting of these areas is
now complete. The sun dial, located originally in the old alpine garden on the main campus, has been 43
moved to the new Physick Garden. The Arbor Garden will be planted with an extensive collection of
scandent and twining plants to provide a display of materials suitable for growing in the Vancouver
area.
Research Associates — Two research associates were appointed to the Garden during 1976. Dr. C. E.
Beil, previously an ecologist with the Department of Botany at U.B.C, and Dr. L. K. Wade, an
ecologist and head of the Department of Biology at Capilano Community College, are working with
the Botanical Garden on specialized programs. Dr. Wade is in charge of a phenological study of the
genus Rhododendron in the Lower Mainland of B.C., with publication of the results slated for 1979
at the time of the American Rhododendron Society Annual Meeting in the city of Vancouver.
Meetings of Note — Two major meetings were hosted by the Botanical Garden during this summer.
The First Interim International Rock Garden Conference was held in Seattle and Vancouver, with
more than 500 delegates attending. A most interesting program was presented during the U.B.C.
portion of the meetings, and the Alpine Garden Club of British Columbia served as the host club.
A special series of workshops were held in the new Botanical Garden area and there were extensive
displays of trough gardens, thanks to the efforts of members of the Botanical Garden staff and the
Alpine Garden Club of B.C. Fine weather prevailed and the alpines were in reasonable condition
considering the time of the season.
A special symposium hosted by the Botanical Garden and sponsored by the International Union
of Forest Research Organizations was held during the last week of the United Nations Habitat conference in the city. This special symposium was concerned with the use of trees in the urban environment and delegates came from throughout North America to attend the meeting. The proceedings of
this symposium have been recently published as a book, entitled Trees and Forests for Human Settlements, by the University of Toronto Press. Special Programs — The Point Grey Cliff Erosion Control Program, concerned with revegetation of
cliffs, was continued under the direction of Dr. C. J. Marchant. This program was supported in part
by the British Columbia Provincial Government (through their summer program for students) and by
a grant from the President's Office. The B.C. Forest Service also provided support by donating
15,000 trees. The program has resulted in revegetation of specific cliff test sites. The evaluation of the
usefulness of various plant materials and their ability to stabilize and control erosion on the cliff test
areas will continue. It is anticipated that a special technical bulletin will be produced to provide the
information to other resource area managers interested in erosion control through revegetation.
Special Donation — B.C. Greenhouse Builders Ltd. have donated a small home greenhouse to the
Botanical Garden for demonstration purposes and use in extension programs. This greenhouse is
used in our program devoted to the management of home greenhouses.
A New Publication — In the Spring of 1976, Meet the Natives — the B.C. Native Plant Garden
Resource Book was produced by the Botanical Garden. The book was prepared in cooperation with
the Vancouver Environmental Education Program of the Faculty of Education at the University. It
provides a basic resource book for teachers interested in using native plant materials in their classroom and making use of the resources of the B.C. Native Garden component of the U.B.C. Botanical
Garden.
Climatological Summary4
44
Data                                                   1976
JULY
AUGUST
SEPTEMBER
Average maximum temperature
19.5°C
18.0°C
18.2°C
Average minimum temperature
12.5°C
12.7°C
n.6°c
Highest maximum temperature
23.8°C
22.8°C
24.4°C
Lowest minimum temperature
9.4°C
10.6°C
7.2°C
Lowest grass minimum temperature
2.2°C
5.0°C
0.6°C
Rainfall/no. days with rain
30.4 mm/12
81.3 mm/12
48.3 mm/8
Total rainfall since January 1, 1976
713.7 mm
795.0 mm
843.3 mm
Snowfall/no. days with snowfall
0
0
0
Total snowfall since October 1, 1975
82.8 cm
82.8 cm
82.8 cm
Hours bright sunshine/possible
243.2/482.5
138.1/439.0
179.5/372.2
Ave. daily sunshine/no. days total overcast
7.8/1
4.4/6
6.0/4
*Site: The University of British Columbia, Vancouver, B.C., Canada
Position: lat. 49° 15f29"N; long. 123° U'58" W. Elevation: 104.4 m
Opposite: A view of the Arbor Garden, with the Contemporary Garden and the partly-completed Physick Garden in the foreground. The tall Douglas Fir visible behind
the Arbor Garden approaches 200 feet in height, and is the tallest tree on the U.B.C. campus. >         ■ :   ) '                  •   ■■
m^r #*
%*■&*&„.
pi
*• *=*
*i -'*3ts
t'- '■«*■
i .•
<w> <■ \
^ The Teddy Bear Cholla (Opuntia bigelovii)
is formidably armed, with joints that are
easily detached from the parent plant.
It is found from southwestern Utah to
Baja California.
Volume 7
Number 3
DAVIDSONIA
Fall 1976
Contents
Cacti and Succulents from Mexico   25
Acer circinatum, Vine Maple   32
Pool and Bridge Renovations in the Nitobe Garden   38
Botanical Garden News and Notes   43
Climatology   44

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