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Davidsonia Jun 1, 1981

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VOLUME    12
Summer 1981 Cover:
Lonicera cv. Dropmore Scarlet, Red
Dropmore Honeysuckle, is one of the vines
growing in the Arbor Garden.
The new flag of The Botanical Garden was
flown for the first time during the opening
of the Physick and Asian Garden
components on May 12, 1981. The Garden
logo, representing the theme of Plants and
Man, is orange, brown and green on a white
field, with a green band to the left.
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VOLUME    12
Summer 1981
Davidsonia is published quarterly by The Botanical Garden of The University of British Columbia, Vancouver, British Columbia, Canada V6T 1W5 Annual subscription, ten dollars.
Single numbers, two dollars and fifty cents, except for special issues. All information concerning subscriptions should be addressed to the Director of The Botanical Garden. Potential contributors are invited to submit articles and/or illustrative material for review by the
Editorial Board.
© 1981 by The Botanical Garden, The University of British Columbia.
The pen and ink illustrations are by Mrs. Lesley Bohm. The illustration facing page 29 is
taken from a color print originally photographed by Dr. Janet R. Stein, Botany Department,
UBC. The drawings for Figures 1 to 3 were provided by Clive Justice of Justice, Webb & Vincent Landscape Architects Ltd., Vancouver. Dr. Fred Ganders provided the illustrations
(Figures 9 to 18) for his article on Genetic Variation. The photographs for Figures 8,19-22,
24, 26 and 27 were taken by Mrs. Sylvia Taylor, and those for Figures 23 and 25 were taken
by Mr. James Banham of Information Services, UBC. Mr. Roy Forster provided the
photographs for Figures 28 and 29.
ISSN 0045-9739
Second Class Mail Registration Number 3313 The Arbor Garden
The Arbor Garden is one of the eight components of The Botanical Garden. It reflects in its
form one of the meanings of the word "arbor" — A recess formed by intertwining vines on a lattice work. However, it also has a unique form in cross-section, which will reflect the sloping roof
outline and configuration of the Warm Temperate, Xeric and Research Glass Houses that make
up the components in the yet-to-be-built Botanical Garden building. The Arbor Garden is the stalk
or leaf tip for this long-planned core or main mid rib of the University's Main Botanical Garden.
The major purpose of the Arbor Garden component is the growing thereon of the widest possible range of cool temperate species and varieties of vines and climbers. The structure provides
for the display of these vines on horizontal, vertical and sloping surfaces on vertical columns and
posts, horizontal and sloping beams, rails and fascias.
Vines have long been neglected and ignored as a significant landscape element. A further
objective of displaying these vines will show the possibilities of vines for the enhancement and
beautification of wall surfaces and structures. Vines can enrich, enhance and add color to the
many unpainted, bland textured, dull and lifeless colored concrete walls of buildings currently
making up a large part of our urban environment. The complimentary uses for vines and creepers OQ
as ground covers and drapery over walls will be exploited on the walls and sloping soil areas
around the just-completed Main Garden Centre building, which is adjacent to the Arbor Garden.
The structure of the Arbor Garden consists of large dimension rough sawn timbers supported
by rows of 4-pole columns. This post and beam structure supports variously oriented panels with
wood frames and grid supporting a fabric of plastic-covered welded wire. The footings for the
4-pole columns were set 60 cm below grade so that the vines could be planted right against and
among the poles. The poles that make up the columns are Lodgepole Pine (Pinus contorta var.
latifolia), chosen because of their consistent straight and even dimension throughout the length.
The beams, timbers and framing members are coastal Douglas Fir (Pseudotsuga menziesii), which
is the best structural wood of all the British Columbian softwood species used commercially.
The Arbor construction uses cross lap, half lap and bolted joints in familiar ways long used in
railroad trestle, wood bridge and sawmill construction. Some of these details are shown in Figures
1 to 3. The Arbor is 49 m (160') long with central sloping panels that reach a height of 9 m above
ground. This height will enable several vines to flower — some species must grow to a height of
7.5 m or more before they will set flowers (for example, Dutchman's Pipe, Aristolochia durior).
Pipes between the double cross beams at each pair of 4-pole columns are high enough to allow
baskets to be hung for the display of half-shade hanging plants, such as fushsias and begonias, as
well as newly discovered or not-yet-available plants possible for use in hanging baskets. These
will supplement the current range of material available for this highly popular item in local
The Arbor Garden's 3 m wide, covered walkway space was also designed to allow rows of stepped staging and tables to display and permit the judging of cut and potted flowers, Bonsai and
other plant displays. This use of the Arbor as a flower and plant showplace can become a
possibility now that there are complete services available in the newly-completed adjacent Main
Garden Centre.
* Clive L. Justice, Justice, Webb & Vincent Landscape Architects Ltd, 6435 West Boulevard, Vancouver, B.C. V6M 3X6 30
FF ;   '! T~T::
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FIGURE 1. The Arbor, east elevation and plan. CROSS    SECTION
FIGURE 2. The Arbor, cross section. Top, a view of the cross beams. 32
-  -'-__•;■.—-V
——n -—*r   -   -*-
FIGURE 3. The Arbor, west elevation and plan As with all the garden components in the Botanical Garden, the Arbor Garden fulfills several
purposes:- the scientific botanical purpose for the study of the many species of plants that climb;
the structure, which shows our local heritage in the use of timbers and poles; and the Garden's
theme of displaying plants for a fuller and closer appreciation by people,
FIGURE 4. Akebia quinata, Five-leaf Akebia,
x 05. APPENDIX. Plants Crowing In The Arbor Garden*
Akebia quinata (Houtt.) Decne. "Five-leaf Akebia" (Lardizabalaceae). (Figure 4). A semi-evergreen twining shrub, 9-12 m
long. The leaves consist of 5 radially arranged leaflets. The flowers are very fragrant, and appear in May in slender pendent
racemes with the sexes separate. The male flowers are 6 mm across, with pale purple reflexed sepals, and are in the terminal part of the raceme. There are usually 2 female flowers at the base of the raceme, each 2.5-4 cm across, and with dark
chocolate-purple concave sepals. The fruit is 6-10 cm long, grayish-violet or purple, and is edible although insipid.
Aristolochia durior J. Hill "Dutchman's Pipe" (Aristolochiaceae). (Figure 5). A deciduous woody climber, to 9 m. The leaves
are reniform-orbicular and up to 30.5 cm long. The flowers are solitary, tubular but bent in the lower half, up to 7.5 cm long,
and yellowish-green with brownish-purple spreading lobes. The flowers appear in June and July. The capsule is cylindrical
and about 7.5 cm long.
Berberidopsis coral Una Hook, f. "Coral Plant" (Flacourtiaceae). An evergreen, scandent shrub, reaching 4.5-6 m. The leaves
are heart-shaped or ovate, and leathery. The flowers are in terminal racemes, deep crimson, globose, 12 mm across, and
appear from July to September or October. The fruit is a berry.
Campsis X tagliabuana (Vis.) Rehd. cv. Madame Galen "Trumpet Vine" (Bignoniaceae). A vigorous climber to about 9 m.
The leaves are pinnate with 7-11 leaflets. The orange and scarlet flowers appear in August to September in terminal pendulous racemes. They are trumpet-shaped, 5-8 cm long, and 6 cm in diameter.
Celastrus scandens L. "American Bittersweet" (Celastraceae). A deciduous shrub with twining branches, growing to 7.5 m.
The leaves vary from obovate to orbicular, are 5-10 cm long, and sharply pointed. The small, yellowish-white flowers are in
terminal racemes or panicles up to 10 cm long, and the sexes are on separate plants. Female plants bear yellow to orange
capsules containing scarlet covered seeds. The fruiting branches are good for fall ornamental dried flower arrangements
Clematis cirrhosa L. var. balearica (L. Rich.) Willk. & Lange "Fern-leaved Clematis" (Ranunculaceae). An evergreen climber,
reaching 3.5-4.5 m. The leaves are much divided, and become bronzy-purple in winter. The flowers are pale yellow or
greenish-yellow, spotted inside with red or reddish-purple, 4-5 cm across, and are present from September to March.
Clematis montana Buch.-Ham. ex DC. var. rubens Kuntze "Pink Anemone Clematis" (Ranunculaceae). A variety with
bronze-purple shoots and leaves. The flowers are solitary, rosy-red to pinkish, 5-6 cm across, and appear in May and June.
Clematis montana Buch.-Ham. ex DC. cv. Tetrarose (Ranunculaceae). The foliage is bronze, and the solitary flowers are
lilac-rose or purplish-pink, up to 7.5 cm across, and appear in May and June.
*\A Clematis x vedrariensis Hort. Vilm.-Andr. cv. Highdown (Ranunculaceae). A climber, to 6 m, with downy foliage. The
flowers are small, pink and appear in May to June.
Clematis cv. Ville de Lyon (Ranunculaceae). (Figure 6). A large-flowered hybrid Clematis with the flowers bright carmine-
red, deeper at the margins, and golden stamens, appearing in May or June to September.
Garrya elliptica Dougl. "Silk-tassel" (Garryaceae). An evergreen shrub or small tree, to 7.5 m, with the sexes on separate
plants. The leaves are elliptic to ovate-lanceolate, and 5-10 cm long The male catkins are 7 5-20 cm long, and grayish-
green. The female plant produces long clusters of deep brown fruits.
Hedera canariensis Willd. "Algerian Ivy" or "Canary Island Ivy" (Araliaceae). An evergreen climber with dark purplish-red
or burgundy red stems and petioles The juvenile leaves are kidney-shaped, and up to 15 or 20 cm long. The adult leaves are
rounded. The leaves often turn deep bronze with green veins in winter.
Hedera canariensis Willd. cv Variegata (Araliaceae). Also known as 'Cloire de Marengo' The large leaves are irregularly
marked with creamy-white on the margins, passing into gray-green, with the normal green occurring in irregular splashes
along the main veins The stem is purplish-crimson.
Hedera colchica K. Koch cv. Dentata-variegata (Araliaceae). The large, ovate to elliptic leaves are weakly and sparsely denticulate, and are bright green shading to gray-green with the margins creamy-yellow when young but becoming creamy-
white when mature.
Hedera helix L. "English Ivy" or "Common Ivy" (Araliaceae). The juvenile leaves are typically 5-lobed, 5-7.5 cm long, and
dark glossy green with whitish veins above.
Hedera helix L. cv. Baltica "Baltic Ivy" (Araliaceae) A naturally occurring variety that is similar to English Ivy, except with
smaller leaves and very pronounced white veins. It is hardier than the typical form
Hydrangea anomala D Don subsp petiolaris (Sieb. & Zucc ) McClint. "Climbing Hydrangea" (Hydrangeaceae). A deciduous
shrub, reaching 18-24 m, attaching by aerial roots. The leaves are broadly ovate, abruptly pointed, 3.5-11.5 cm long, and
dark green. The greenish-white flowers open in mid-June to July in terminal corymbs, 15-25 cm across. There are several
large, conspicuous, white, sterile florets around the margin of the corymb.
lasminum beesianum Forr. & Diels "Rosy Jasmine" (Oleaceae). A deciduous scandent shrub, growing to 3.5 m. The leaves
are opposite, taper to a long point, and dull dark green. The flowers are fragrant, deep violet-red or rose, up to 1.25 cm long,
and in 1-3 flowered cymes, opening from May or June to July. The fruit is a shining black berry.
* By Sylvia Taylor FIGURE 5. Aristolochia durior, Dutchman's
Pipe, X 0.75.
FIGURE 6. Clematis cv. Ville de Lyon, X 0.5
35 36
lasminum nudiflorum Lindl. "Winter Jasmine" (Oleaceae). A deciduous shrub, to 4.5 m. The leaves are opposite, with 3
oblong or ovate leaflets The flowers are bright yellow, solitary, 1 2-2 5 cm across, and appear on the naked branches from
November to February
lasminum officinale L "Common White Jasmine" (Oleaceae). A deciduous scandent shrub, to 9-12 m. The leaves have 5-7
ovate leaflets, the terminal one being the largest The white, fragrant flowers open from June to September, and are in
clusters of 3-5.
Lapageria rosea Ruiz. & Pav "Chilean Bellflower" or "Chile-bells" (Philesiaceae). An evergreen woody vine, to 4.5 m. The
leaves are alternate, leathery, ovate-lanceolate, 5-7.5 cm long, and dark glossy green. The flowers are pendulous, solitary
or in twos or threes, rose-crimson faintly spotted with rose, 7.5 cm long, 5 cm wide, and appear in the summer and fall. The
fruit is an oblong-ovate berry. The national flower of Chile
Lonicera cv. Dropmore Scarlet "Red Dropmore Honeysuckle" (Caprifoliaceae). A tall-growing climber, with clusters of
bright scarlet, tubular flowers from July to September. A cultivar developed in Dropmore, Manitoba.
Lonicera henryi Hemsl. "Henry's Honeysuckle" (Caprifoliaceae). (Figure 7). An evergreen or semi-evergreen climber. The
leaves are oblong-lanceolate, and to 7.5 cm long. The flowers are yellowish marked with red, to 2 cm long, and borne in terminal clusters in June and July. The berries are blackish-purple to black.
Parthenocissus quinquefolia (L ) Planch. "Virginia Creeper" (Vitaceae). A deciduous climber with adhesive discs at the ends
of the tendrils. The leaves are alternate with 5 elliptic-ovate leaflets, each up to 15 cm long, and dull green, becoming
brilliant orange and crimson in the fall. The small greenish flowers are in compound paniculate cymes The fruit is a blue-
black berry.
Parthenocissus tricuspidata (Sieb. & Zucc.) Planch. "Boston Ivy" or "Japanese Creeper" (Vitaceae). A vigorous deciduous
vine, to at least 18 m, with adhesive discs at the ends of the tendrils. The leaves are extremely variable, broadly ovate and
toothed or trifoliate on young plants, ovate and conspicuously 3-lobed on old plants They turn crimson and scarlet in the
fall. The flowers are small, yellow-green, and are in cymes. The fruit is a blue-black berry.
Parthenocissus tricuspidata (Sieb & Zucc.) Planch, cv, Lowii (Vitaceae). A selection with small, curiously crisped, palmately
3- to 7-lobed leaves, and rich fall color.
Parthenocissus tricuspidata (Sieb. & Zucc.) Planch, cv. Veitchii (Vitaceae). A selected form with slightly smaller, ovate or
trifoliate leaves that are purple when young.
Passiflora caerulea L. cv. Constance Elliott "Passionflower" (Passifloraceae). A vigorous climber with palmately 5- to
7-lobed leaves. The flowers are ivory-white, 5-10 cm across, fragrant, and appear from June to September or later.
Polygonum aubertii L. Henry "Silver Lace Vine" or "China Fleece Vine" (Polygonaceae). A vigorous twining perennial vine,
to 6 m. The leaves are ovate-lanceolate, and up to 6 cm long. The white to greenish-white flowers are in long, erect, pan-
icled racemes, and appear in late summer.
FIGURE    7.
x 0.75.
henryi,    Henry's Rosa banksiae R. Br. in Ait. f. cv. Lutea "Yellow Banksian Rose" (Rosaceae). A semi-evergreen climber, reaching 6-12 m,
with few to no prickles. The flowers are double, yellow, 2.5 cm across, slightly fragrant, and appear in late spring to midsummer.
Senecio scandens Buch.-Ham. ex D. Don (Asteraceae). A semi-evergreen, semi-woody climber with long scandent stems
reaching 4.5-6 m. The leaves are ovate or narrowly triangular, sometimes lobed at the base, and up to 10 cm long. The
flower heads are yellow, 1.25 cm across, in terminal or axillary clusters, and appear in October and November.
Wisteria floribunda (Willd.) DC. "Japanese Wisteria" (Fabaceae). A deciduous climber, often reaching 10 m or more, stems
twining clockwise. The leaves are 25-38 cm long, and are divided into 13-19 leaflets. The flowers are fragrant, violet to
violet-blue, in slender pendent racemes 12.5-25 cm long, and opening successively from the base onwards in late May with
the leaves.
Wisteria floribunda (Willd.) DC. cv. Rosea "Pink Wisteria" (Fabaceae). A form with fragrant, pale-rose flowers, tipped purple, in racemes to nearly 46 cm long, in late May to June.
Wisteria sinensis (Sims) Sweet "Chinese Wisteria" (Fabaceae). A vigorous deciduous climber, reaching 18-30 m, with old
trunks often reaching 1.5 m in circumference. The stems twine anti-clockwise. The leaves are 25-30 cm long, and usually
have 11 leaflets. The flowers are mauve or deep lilac, not fragrant, 2.5 cm long, and carried in racemes 20-30 cm long, with
all the flowers opening simultaneously. They appear in mid to late May, before the leaves.
Wisteria sinensis (Sims) Sweet cv. Alba (Fabaceae) A form with white, very fragrant flowers.
The following Vitis cultivars are planted in the extension of the Arbor on the east side of the Economic Garden.
cv. Himrod
cv. Interlaken
cv. Leon Mallet
cv. Madeleine Angevine
cv. Muller Thurgau
cv. Pinot Noir
cv. Sauvignon Blanc
cv. Seyval Blanc
cv. Siegerrebe
cv. Vidal 256
FIGURE 8. The east side of the Arbor. Vitis cultivars hardy to British Columbia will be grown up the ten poles,
and espaliered dwarf fruit trees will be trained against the concrete retaining wall. Genetic Variation in Plants of
British Columbia. I. Mutations
Many people like to identify trees and wildflowers, or collect them or grow them in their
gardens. Observing the diversity of nature is enjoyable. Careful observation of nature reveals
another finer level of diversity: variation within populations of a single species. Our thesis is that
this fine-scaled observation can add another dimension to the enjoyment of nature.
This is the first of a series of three articles on genetic variation in wild plants of British Columbia. The purpose of this series is to illustrate some of the kinds of genetic variation that occur
within natural populations of our trees, shrubs, wildflowers, and weeds. Very little is known about
genetic variation in the native plants of British Columbia, and consequently many of the examples are cases that we or our students have studied. However, the field is wide open for interested
amateur naturalists and gardeners to observe, preserve, and study variation in our flora.
Variation can have many causes. Some are not genetic. Some variation is caused solely by differences in the environment. For example, mature plants of Sea Blush, Plectritis congesta subsp.
brachystemon, range in height from 10 cm to 1 m depending on the availability of moisture and
soil nutrients. Such differences between plants in nature will disappear if they are grown under
38 uniform conditions. Size variation in this species is not genetic variation, but is solely the result of
environmental differences.
Some plants go through characteristic developmental stages, often called juvenile stages, in
which the individuals appear different from the mature form. Juvenile foliage that differs from
adult foliage is a common example of developmental variation. Distinctive juvenile foliage
occurs in Rocky Mountain Juniper, Juniperus scopulorum, and in Red Huckleberry, Vaccinium
parvifolium. In Red Huckleberry, juvenile leaves are dark green, toothed, thick, and evergreen,
while adult leaves are lighter green, with entire margins, thinner, larger, and deciduous (Figure 9).
Genetic variation is variation caused by different genes. But what exactly are genes?
The story begins inside the nucleus of the cells. Organisms are simply large masses of cells.
Each cell has a nucleus, and in each nucleus there are rod-like structures called chromosomes.
There are many unique types of chromosomes in a cell, and each cell of the body has the same
total chromosome complement. A chromosome is basically several inches of a thread-like
chemical called DNA, and this length is tightly coiled up for convenient packaging. The DNA is
divided up into areas that are the genes. An analogy for a chromosome might be a yardstick (the
total DNA of that chromosome) upon which inch #1 is one kind of gene, #2 another kind of gene,
and so on.
In higher plants and animals, each cell has two identical sets of chromosomes. Originally, one
set came from the mother (in the egg) and the other from the father (in the sperm). Hence each
cell has 2 copies of every kind of gene. These we will call gene pairs. But what about variation?
The fact is that a specific gene can exist in several forms and these forms are called alleles. As an
example, let us consider the gene responsible for the presence or absence of purple spots on the
leaves of Small-flowered Blue-eyed Mary, Collinsia parviflora. One of its alleles determines that
purple spots are present and the other determines that they are absent. They affect this character
in two different ways.
* Department of Botany, University of British Columbia, Vancouver, B.C. V6T 2B1 FIGURE 9. Adult and juvenile foliage of Red
Huckleberry, Vaccinium parvifolium, X 0.5.
Adult foliage (above) is deciduous, and the
leaves are thin with entire margins. The
juvenile leaves (below) are evergreen,
smaller, thicker, and have serrate margins.
Genes and their alleles are represented by letter symbols. Alleles of one gene are given the
same letter symbol. The spotted leaf allele might be called S, and the unspotted allele s. The
capital and lower case letter symbols have a further important meaning in that the capital letter
denotes a dominant allele, and the lower case denotes a recessive allele. The dominant allele is
simply the one that 'wins' when the dominant and recessive alleles are found together in an
individual. For example, a plant of constitution §s (called a heterozygote) would be spotted,
whereases.and is (called homozygotes) would be respectively spotted and unspotted.
All cells of the plant have genes in pairs except the pollen and egg cells. In the cell division that
produces such cells, the total number of chromosomes is halved, from two sets into one set. At
this cell division one allele of each gene pair ends up in half the sex cells, and the other allele
ends up in the other half. If the plant was homozygous, all sex cells get the same allele.
Therefore, if homozygous plants are self-pollinated, the progeny will be homozygous and like
their parent. But if a homozygous spotted plant is pollinated by a homozygous unspotted plant,
the offspring will get one S allele plus one s allele and thus be heterozygous. Since presence of
spots is dominant, the heterozygotes are spotted. If a heterozygous spotted plant is self
pollinated, 3A of the progeny are spotted and Va are unspotted. This 3:1 ratio, in fact, proves that the variation (the difference between the plants) was caused by an allele difference of a single
gene, and that the allele for spotted leaves is dominant. This is explained in the following chart in
which the above steps are represented symbolically, using S for the allele for spotting, and s for
the allele for no spots.
spotted S^ S
_s_s unspotted
sex cell       S^
(egg or
spotted hybrids
^^.^ hybrid pollen
Vi S.
Vi s_
hybrid egg               "^^^^^
Vi S
V* Ss_
V* ss.
Va Spotted
Va Unspotted
In doing actual experiments one may not get exactly a 3:1 ratio, however. Figure 10 shows one
leaf from each of the progeny from self pollinating a heterozygote for spotted leaves in Collinsia
parviflora. If you count them you will see that the ratio is very close to 3:1.
The beginning of all genetic variation is mutation, for mutations are changes in the genes
themselves. Mutations are heritable and the altered gene may be passed on to future generations.
The chemical nature of mutation is fairly well understood, but need not concern us here.
Although mutations can be induced artificially, with chemicals and radiation, they are also constantly occurring spontaneously in populations of organisms. Many are deleterious or even lethal
if they affect a gene that is crucial for the normal metabolism or development of the organism.
Others are neutral; they have no effect, or the change is immaterial to the survival of the
organism. A few are advantageous, and make the organism better able to survive. Actually, this is
a little misleading, since a wide variety of mutant genes is usually found in large populations, and
whether or not they are disadvantageous or advantageous depends on the environment in which
the organism happen:; to be living. That is, a particular gene may be deleterious at one point in
time, neutral in another, or advantageous at another time. A rare mutant gene may already be
found in a population when the environment changes and the mutant allele then becomes
favorable, and is selected.
Because mutations are always occurring, if one looks at enough individuals one is certain to
find some kind of mutant. We have found a large number of mutants and polymorphisms in the
small annual plants Rosy Plectritis or Sea Blush, Plectritis congesta, and Small-flowered Blue-eyed w?
FIGURE 10. Spotted and unspotted leaves of Small-flowered Blue-eyed Mary, Collinsia parviflora. Each leaf is
from a different plant in the progeny of a self-fertilized hybrid spotted plant. 42
Mary, Collinsia parviflora. Populations of small annuals frequently contain many thousands of
plants, and so it is easy to observe a large number of plants in a short time. Also, populations of
annual plants consist of new individuals each year, while populations of perennials may frequently
consist of the same individuals for many years. Therefore, genetic changes and mutant genotypes
are produced more frequently in annuals, and consequently your chances of finding mutants are
higher in populations of small annuals. Annual plants are most common in areas or habitats with
a pronounced dry season, such as the rocky hills and bluffs of southeastern Vancouver Island and
the dry interior valleys of the Province. An added factor is that the displays of spring wildflowers
in these areas, such as in the many parks around Victoria, are exceptionally pleasant places to
observe variation in our native plants.
A good example of a single gene mutation affecting flower form is the mutant known as peloria
in Foxglove, Digitalis purpurea. Peloric Foxgloves are characterized by an abnormal flower at the
top of the inflorescence (Figure 11). The large cup-shaped terminal flower is actually formed from
several fused flowers, as can be seen by the additional corolla lobes, stamens, and pistils. Despite
its abnormal form, the peloric terminal flower is fertile and will set seed. The other flowers on the
inflorescence are normal in shape.
Peloria is caused by a single recessive gene, with the peloric plants homozygous recessive
Because peloric plants are homozygous, they "breed true". That is, if self-pollinated or crossed to
other peloric plants, all the offspring will also be peloric. Therefore, this mutant has been easy to
preserve in certain garden cultivars of Foxglove.
In a peloric plant all the pollen and eggs produced carry the recessive allele, even those produced by the normal flowers on the plant. Thus, whether one self pollinates the terminal flower or
one of the normal flowers, all progeny will show an abnormal terminal flower. Although all cells
of the peloric plants carry the genes for peloria, they are expressed only in the development of the
terminal flower.
Peloric mutants have been known in Foxglove and cultivated for a long time. In fact, the
genetics of this condition, as well as the genetics of flower color in Foxgloves, was first worked
out in 1910. The peloric mutant is found in populations of Foxgloves in B.C. in very low frequencies, and it is likely that the gene was originally introduced from peloric plants cultivated in
gardens. The plant photographed was the only peloric type in a large population on the University
Endowment Lands in Vancouver.
Other kinds of mutations affecting flower form or shape are found in a wide variety of plants.
Such mutants may be at a selective disadvantage if they change flower morphology to such an
extent that the flowers no longer attract pollinators, or are less efficiently pollinated by visiting
insects. On the other hand, natural selection by pollinators has been responsible for the myriad of
shapes exhibited by flowers. In addition, some flower-form mutants that may be disadvantageous
under natural conditions have been brought into cultivation by man, good local examples being
the double-flowered Salmonberry, Rubus spectabilis, and Western Thimbleberry, Rubus par-
Salmonberry flowers typically have 5 petals and numerous stamens, as do most species of
Rubus. The flowers of the so-called "double flowered" mutants of this species (Figure 12) have
numerous petals, but the stamens and pistils at the centre of the flower are still visible. The double
flowers are somewhat larger than the normal single flowers in Salmonberry.
Developmentally the extra petals represent modified stamens. This is a relatively common
mechanism by which double flowers are formed, and consequently double flowered mutants and
cultivars are often found in species that have numerous stamens to begin with. Double flowered
Salmonberries have been found several times in British Columbia and Washington State, and
brought into cultivation, where they can be propagated vegetatively. Specimens may be seen at
Heritage Court, near the British Columbia Archives Building in Victoria, at the University of
British Columbia Botanical Garden, and at the University of Washington Arboretum, Seattle.
Normally the ray flower petals of Arrow-leaved Balsamroot, Balsamorhiza sagittata, are flattened, FIGURE 11 (left). A peloric Foxglove, Digitalis
purpurea, X 1.0. The large cup-shaped terminal flower represents several flowers fused
FIGURE  12 (below).  Double-flowered (left)
and   single-flowered   (right)   Salmonberry, 43
Rubus spectabilis, X 1.0. 44
FIGURE 13. Normal (right) and mutant (left and top) flowers of Arrow-leaved Balsamroot, Balsamorhiza sagit-
tata. The mutant form has ray flowers that are tubular at the base rather than flattened.
but in one mutant plant (Figure 13) they are tubular at the base and flattened only at the tips, giving the flower head the appearance of a spoked wheel. The flower heads are also slightly smaller
than those of normal balsamroots. The mutant plant was found by Dr. Roy Taylor, Director of the
University of British Columbia Botanical Garden, growing along Lambly Creek near Lake
Okanagan. The form of the mutant is analogous to some cultivars of chrysanthemums, which
have been selected for unusual flower forms for thousands of years.
Mutations that affect flower color are perhaps the easiest of all to find because they are conspicuous. The most common flower color mutants are found in plants with red to purple or blue
flowers. Most of these flowers owe their color to water soluble pigments called anthocyanins,
which are dissolved in the vacuoles of the cells of the flower. The colored pigments are synthesized
by a variety of chemical reactions controlled by biological catalysts called enzymes, using colorless chemicals as their starting materials. There are frequently several different anthocyanins
within the same flower, and the different anthocyanins may or may not be synthesized from each
other, again by reactions controlled by enzymes.
Mutations producing defective or non-functional enzymes prevent the synthesis of the
pigments. Such mutations are usually recessive, because a plant that is heterozygous has a
mutant allele and a normal allele, and the normal allele will produce some functional enzyme so
that the reaction to produce the pigment can take place. If the mutant gene is homozygous,
however, all the enzyme produced is defective, and the reaction cannot proceed. If the enzyme
affected is one necessary for the production of anthocyanin pigment, then the flower will lack
anthocyanins and be white in color. An example is a white flowered plant of Red Clover, Trifolium
pratense, which we found along Marine Drive on the University of British Columbia campus
(Figure 14). The white flowered plant is not White Clover, Trifolium repens, which is a different
species that differs in many other ways. A mutation may prevent the production of anthocyanins
only in the flowers, or everywhere in the plant On the other hand, a mutant enzyme that is only
involved in changing one anthocyanin pigment into another one will not result in complete
absence of anthocyanins, but only in the loss of particular ones. The result could be a change of FIGURE 14 A white-flowered mutant (left) of Red Clover, Trifolium pratense, and a flower bead from a normal
plant (right).
flower color from blue to pink, for example. Mutant genes need not always produce defective
enzymes, but the altered enzyme might change the chemical reaction and produce a different pigment.
Small-flowered Blue-eyed Mary, Collinsia parviflora, is an annual that occurs in the coastal and
southern parts of the Province, but is especially common and conspicuous on Vancouver Island
and the Gulf Islands, where it flowers from March to May. Normally the flowers have a blue lower
lip with the upper lip magenta, magenta and blue, or blue and white.
We found a small clump of about two dozen plants of Collinsia parviflora with pure white
flowers at Mt. Douglas Park near Victoria, The plants were all growing within inches of each other
and most certainly represented the descendants of a single original mutant. Crossing experiments
have shown that the white flowers are caused by a single recessive gene, that blocks all anthocyanin production in the plant. Heterozygotes are indistinguishable from homozygous normal
Small-flowered Blue-eyed Marys.
These white flowered mutants proved to be more susceptible to disease and fungal attackthan
normal plants. It is interesting that red onions, which have anthocyanins in their bulbs, are more
resistant to fungal diseases than are white and yellow onions, which lack anthocyanins. This suggests that anthocyanin pigments may play a role in disease resistance as well as being flower
Magenta or pink flowered mutants of Collinsia are at least as frequent as white ones. We have
seen plants from Elk Falls and Nanoose Hill that had completely pink flowers, without a trace of
blue. Genetic studies showed that pink flowers were also controlled by a single recessive gene.
The allele for pink flowers is not at the same gene locus as the allele for white flowers, for when
pink and white flowers are crossed, the offspring (F-| generation) had normal blue flowers. When
these F-| blue flowers were self pollinated, the F2 progeny contained blue, pink, and white
flowered plants. The genetics of these flower color mutants is a good example of how genes work to regulate
the biosynthetic pathways in the plant. Biosynthetic pathways are the series of chemical reactions in living organisms that produce the chemicals that make up the organism. The diagram
shows how flower color pigments in Collinsia are synthesized. A colorless precursor or starting
compound is changed into a pink pigment by a reaction controlled by enzyme W, produced by
gene W. The recessive mutant gene w produces a defective enzyme w, that cannot carry out this
chemical reaction. Therefore, in a plant homozygous for ww, the reactions stop at this point and
no flower color pigment is synthesized. The flower will be white. A plant with at least one W
allele will make the pink pigment.
In the next step of the biosynthetic pathway, an enzyme P, produced by gene P, converts some
of the pink pigment to a blue pigment. The mutant allele p produces a defective enzyme p that
cannot convert pink pigment to blue pigment. So a plant with at least one W allele at the W gene,
but homozygous £p at the P gene can carry out the reactions of the biosynthetic pathway up to
the point where pink pigment is produced, but without enzyme P produced by allele P, no pink
pigment is converted to blue pigment, and the flower is pink. A plant with a W allele and a P
allele will be able to complete the biosynthetic pathway, and the flowers will have blue and pink
enzyme W
produced by
allele W
enzyme P
produced by
allele P
A plant that is homozygous ww but has the dominant P allele cannot produce either pink pigment
or blue pigment. Since ww plants cannot produce pink pigment, enzyme P has no pink pigment
available to convert to blue pigment. Even though the P enzyme is available, the chemical reaction it controls cannot occur because no starting material is available.
When a white flowered plant of type wwPP is crossed with a pink flowered plant of type
WWpp, the F-| progeny are heterozygous at both genes, WwPp. Since they have both the domi-
nant W and dominant P, they produce both functional W enzyme and functional P enzyme, and
the entire biosynthetic pathway can proceed, so their flowers have blue and pink pigment.
When these blue flowered plants, heterozygous at both genes, are selfed or crossed with each
other, the F2 progeny will consist of nine different types and all three colors (white, pink, and blue)
as shown below
WwPp    x    WwPp
egg             ^-v^
wwpp The proportions of the various types are:-
1/16 WWPP blue
1/16 WWpp pink
2/16 Wwpp pink
1/16 wwPP white
2/16 wwPp white
1/16 wwpp white
2/16 WWPp blue
2/16 WwPP blue
4/16 WwPp blue
The observable proportions are 9/16 blue, 4/16 white, and 3/16 pink.
Collinsia flowers will self pollinate readily, so the homozygous recessive flower color mutants
found in nature can be propagated by collecting seed from self pollinated flowers. Even if the
flowers have been naturally pollinated with pollen from neighbouring blue flowers and the progeny are heterozygous and blue, a proportion of homozygous mutant types will segregate out in
future generations.
White flowered mutants are relatively common in flowers with anthocyanin pigments, but they
are very rare in yellow flowers. Yellow flowers usually are colored by membrane-bound
carotenoid pigments. The same types of pigments are associated with chlorophyll in the light
energized reactions of photosynthesis. A mutation preventing carotenoid synthesis in the plant
could produce white flowers, but might also prevent normal photosynthesis, and it would be
lethal to the plant long before it could flower.
In plants with bright colored berries, fruit color mutants can be as conspicuous as flower color
mutants. We found an orange-fruited plant of the Red Elder, Sambucus racemosa subsp pubens
var. arborescens, on the University Endowment Lands west of Vancouver (Figure 15). Rare yellow,
chestnut colored, and even white fruited forms of Red Elder have also been reported.
Mutations affecting the vegetative parts of plants are probably even more common than floral
mutations, though not as conspicuous. Leaf form mutants in trees are often propagated
vegetatively as ornamental cultivars. Unusual cut-leaf mutants of Red Alder and Western Birch
(or Water Birch) have been found in British Columbia.
FIGURE 15. Mutant orange berries (left) and normal red berries (right) of Red Elder, Sambucus racemosa
subsp. pubens var. arborescens. FIGURE 16, Presumed mutant leaf form (left) and normal leaves (right) of Red Alder. Alnus rubra, x 0.5.
FIGURE 17 (left). Normal leaves of Western
Birch, Betula occidentalis, X 0.75. Red Alder, Alnus rubra, is probably the most common deciduous tree in the southern part of
coastal British Columbia. The leaves normally have shallow, rounded teeth along their margins.
The cut-leaf mutant form has irregular sharply pointed teeth and lobes on its leaves, so that they
resemble some Black Oak leaves more than they do Alder leaves (Figure 16). The mutant is growing at the University of British Columbia Botanical Garden.
Western Birch, Betula occidentalis, is a small shrubby birch found in the southern interior of
British Columbia, and is distinguished from Paper Birch by its smaller size and by the presence of
wart-like glands on its wings. The leaves are roughly heart-shaped with small teeth along the
margins (Figure 17). In the cut-leaf mutant, found near Revelstoke, the development of the leaf is
limited to narrow regions along some of the main veins so that the leaves resemble mere
skeletons of normal leaves (Figure 18).
FIGURE 18. Dissected leaves of a presumed
mutant plant of Western Birch, Betula
occidentalis, X 0.75. This condition might be
the result of virus infection rather than a gene
49 50
Official Opening of The Physick and
Asian Gardens
A ceremony held on May 12th, 1981 saw the official opening of the Physick Garden, an area devoted to
medicinal and pharmaceutical plf.nts, and the Asian Garden, a 30-acre garden devoted to trees and shrubs of
Asia, with special emphasis on Rhododendron species. In addition to the opening of the two areas, a sundial,
dedicated to Professor Frank Buck, first landscape architect of the University of British Columbia, was unveiled
by the President of the B.C. Society of Landscape Architects, Dr. John W. Neill, and Professor Buck's niece,
Mrs. Monica McGavin. Following the ceremony, the participants in the ceremony had refreshments in the
new Main Garden Centre, which represents the third phase of the three-phase building program of the new
Botanical Garden Research and Administration Centre.
The two garden components represent divergent uses and display of plants relating to our theme "Plants
and Man". Many of the plants in the Physick Garden have come directly from the material contained in the
Chelsea Physic Garden, and we were greatly honored to have Mr. Allen Paterson, Curator of the Chelsea
Physic Garden, officiate at the opening of this garden component. The Physick Garden represents a long-time
interest by The Botanical Garden at the University in medicinal plants. Some of the early work on the evaluation and analysis of Digitalis was conducted by the Chemistry Department on plants grown by the Botanical
Garden in the 1920s. It is appropriate that the growth and development of the medical sciences at the University of British Columbia should be reflected by The Botanical Garden through the establishment of a special
component of particular interest to the pharmaceutical sciences.
The Asian Garden represents a major effort by the University of British Columbia to accumulate an important gene pool resource of Asian trees and shrubs A number of herbaceous plants, which have their origin in
Asia, are also grown in this garden. As many of our fine ornamentals in North America have been derived
from plants of Asian origin, it is appropriate that our climatic similarity to many parts of China, Russia and
Japan should allow us to devote a special component to these particular plants. This garden is connected to
the Main Garden by an underpass under the new Southwest Marine Drive extension, one of the main feeder
routes for people entering the University of British Columbia. It was a particular pleasure to have Mr. Kenneth
Wilson, retired Supervisor of Operations, officially dedicate this garden. Mr. Wilson dedicated the garden to
the many members of staff who have worked on behalf of all components of the Garden. It is undoubtedly a
garden for gardeners as well as a garden for the public, and the recent interest by the B.C Nursery Trades
association and the B.C. Landscape Architects in the introduction of new plant material into our horticultural
world will see the Asian Garden used to great advantage over the next decade.
FIGURE 19. From the left, Mr. J.V. Clyne, Chancellor of the University, Dr. Roy L. Taylor, Director of the
Botanical Garden, Mr. Allen Paterson, Curator of the Chelsea Physic Garden in England, Mr. Kenneth Wilson,
retired Supervisor of Operations for the Garden, and Dr. B.N. Moyls, Director of Ceremonies for the University,
chat before the Ceremonies begin. FIGURE 20 Dr. Douglas T. Kenny, President of the University, welcomes the guests to the opening of the
Physick Garden Left to right: Mrs. Monica McGavin, Dr. John W. Neill, Dr. Michael Shaw, Provost and Vice-
President at UBC, President Kenny, Mr. J.V. Clyne, Dr. Roy L. Taylor, and Mr. Alien Paterson.
FIGURE 21. Mr. Allen Paterson, Curator of the Chelsea Physic Garden, officially opens the UBC Physick
Garden by cutting a yellow ribbon. 52
FIGURE 22 (above). Dr. John W. Neill,
President of the B.C. Society of Landscape Architects, and Mrs, Monica
McGavin unveil the sundial, dedicated
to the memory of Professor Frank
Buck, the first landscape architect at
UBC. Mrs. McGavin is Professor Buck's
FIGURE 23 (right). Dr. John W, Neill
and Mrs. Monica McGavin inspect the
new sundial, which is in the centre of
the Physick Garden. FIGURE 24. The new Main Garden Centre near the Physick Garden, where tea was served following the
Ceremonies. In the foreground are some of the raised beds in the Economic Garden, which is still under
development. OO
FIGURE 25 Mr, Kenneth Wilson, retired Supervisor of Operations at The Botanical Garden, plants a specimen
of Corytopsis sinensis, Chinese Winter Hazel, during the official opening of the Asian Garden. Supervising the
operation are (left to right) Dr. Roy L. Taylor, Mr. J.V. Cfyne, and Dr. Douglas T. Kenny, FIGURE 26. Mr. Kenneth Wilson dedicates
the Asian Garden to all the staff members of
The Botanical Garden who were involved in
the development of the area.
FIGURE 27. Dr. Roy L. Taylor (right) presents Mr. Kenneth Wilson with a plaque honoring Mr. Wilson as the
Third Honorary Life Member of The Botanical Garden. It was awarded in recognition of Mr. Wilson's service
to the Garden between 1969 and 1980. Pinus sylvestris L cv. Boersma —
A New and Distinct Cultivar of Scots Pine
Pinus sylvestris L. cv. Boersma is a clone of decumbent habit that occurred as a seedling liner in
a Scots Pine plantation about 1960. The plantation was located in peat land on Lulu Island, now
Richmond, British Columbia, but it is reported that the lining-out stock originated in New Jersey,
U.S.A. The original plant was found in 1967 and subsequently was transplanted to VanDusen
Botanical Garden in 1974. The plant now measures 3 m in diameter and has a lower trunk
diameter of 8 cm. The branchlets and leaves are within the normal range for Pinus sylvestris
except for the decumbent character. The branchlets (annual growth) are stout, 8-10 mm in
diameter at the base, 20-30 cm long, and yellow-brown in color. The terminal winter buds are
cylindrical and reddish-brown. The leaves are 6-8 cm long, bright green, and glaucous. The sharply
pointed leaf tips may turn yellow in winter.
The older limbs and trunk have a gnarled appearance with furrowed and plated bark, dark
brown in color. Propagation, thus far, has been by grafting on Pinus sylvestris rootstock. The
growth of these grafts has been rapid, with annual growth increment occasionally exceeding
50 cm. Some of these vigorous shoots ascend from the decumbent stems, resulting in a total plant
height of 1 m. However, the decumbent character is retained (Figures 28 and 29).
Pinus sylvestris cv. Boersma is named for Mr. Harry Boersma, who participated in the acquisition of the cultivar and who gave the original plant to the VanDusen Botanical Garden.
It is anticipated that this cultivar will find a place in Dwarf Conifer collections, in large Rock
Gardens, and in landscapes of oriental character where plants of contorted form may be
desirable A limited quantity of scion wood is available to Botanical Gardens and nurserymen.
FIGURE 28. A general view of the habit of Pinus sylvestris cv. Boersma growing in the VanDusen Botanical
* R. Roy Forster. Curator, and Kurt M. Stich, Propagator, VanDusen Botanical Garden, 5251 Oak Street, Vancouver, B C.
V6M 4H1
55 «i^
V   4t\T -■
F1CURE 29. Detail of the individual branching pattern of Pinus sy/vestm cv  Boersma
Climatological Summary
Data                                                    1981
Average maximum temperature
Average minimum temperature
Highest maximum temperature
21 3°C
22.1 °C
Lowest minimum temperature
Lowest grass minimum temperature
- 2.0°C
Rainfall/no. days with rain
141.8 mm/21
103.8 mm/21
126.4 mm/20
Total rainfall since January 1, 1981
484.5 mm
588.3 mm
714.7 mm
Snowfall/no. days with snowfall
10.0 cm
Total snowfall since October 1, 1979
19.3 cm
39.3 cm
39,3 cm
Hours bright sunshine/possible
140 8/482.2
Ave. daily sunshine/no. days total overcast
5.4 hr/7
5.6 hr/3
4.7 hr/4
'Site: The University of British Columbia, Vancouver, B.C., Canada V6T 1W5
Position: lat. 49° 15' 29" N; long. 123° 14' 58" W. Elevation: 104.4 m Botanical Garden Staff
Dr. Roy L. Taylor
Assistant Director
Mr. A. Bruce Macdonald
Research Scientist (Cytogenetics)
Dr. Christopher J. Marchant
Research Scientist (Horticulture)
Dr. John W. Neill (retired June 30, 1981)
Research Technicians
Mrs. Annie Y.M. Cheng
Mrs. Sylvia Taylor
Secretaries to the Office
Mrs Pam Morgan Robin, Secretary
Mrs. Cwynneth M. Quirk, Receptionist
Plant Accession System
Mrs. Marie T. Shaflik
Mr, David A. Tarrant
(Education Co-ordinator)
Mrs. Margaret E Walline
Mr. A. James MacPhail (Alpine Carden)
Mr. Allan A. Rose (B.C. Native Carden)
Mr. Charles E. Tubesing (Nursery)
Mr. A. Peter Wharton (Asian Carden)
Mr. P. Joseph Rykuiter, Head Gardener
(Area Manager, South Campus)
Mr Ronald S. Rollo, Sub-Head Gardener
(Area Manager, Nursery)
Mr Harold Duffill
Mr. Leonard Cibbs
Mr. Kenneth W. Hadley
Mr. Murray J. Kereluk
Mr Paul Kupec
Mrs. Bodil Leamy
Mrs. Elaine V.M. Le Marquand
Mr. Douglas B. McEwan
Mr. Sam M. Oyama
Mr. Andrew J. Prentice
Mr. Isao Watanabe
Mr. Thomas R. Wheeler
Research Associate
Dr. L. Keith Wade
Special Summer Student Programs
Miss Corinne Evans
Mr. Luca Michele Hauner
Miss Jennifer J  Sherlock
Campanula rotundifolia, Common Harebell,
a summer-flowering plant found in the
Interior of British Columbia. Lonicera utahensis, Utah Honeysuckle, a
common cream-colored honeysuckle found
in the Coastal and Cascade Mountains.
Volume    12
Number    2
Summer 1981
The Arbor Garden 29
Genetic Variation in Plants of British Columbia. I. Mutations 38
Official Opening of the Physick and Asian Gardens 50
Pinus sylvestris L. cv. Boersma — A New and Distinct
Cultivar of Scots Pine 55
Climatological Summary 56


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