Botanically Canada has much in common with Scandinavia and Siberia in that a large area consists of rather flat coniferous forest land broken by numerous lakes. Despite the fact that the spruce trees and pines of Canada and the United States look very similar to those in Europe and Asia, they are not the same species. The same applies to many of the small shrubs and herbaceous plants, which are closely allied to species in the Old World, although the differences between them are enough to classify them as separate species. In some instances however they are identical and the little pink twin-flowered Linnea borealis for example, which was named after Linnaeus, the great botanist, grows right round the world in the northern temperate zone. Many European wild flowers have also become naturalized in North America since the European settlers arrived, and are now so widespread that it is often difficult to tell that they are not indigenous. One of these is the showy purple loosestrife, Lythrum salicaria, a European plant, which makes quite an impact in damp places along the eastern sea-board from Canada right down to Delaware.

North America is noted for some of the beautiful members of the lily family found there. These include the tall, graceful and very variable Lilium canadense, which grows in swampy places along rivers and streams, and the orange Lilium philadelphicum which prefers dry hilltops. The exciting golden yellow Erythronium grandiflorum, known as the glacier lily, and its relative the white avalanche lily, E. montanum, appear as soon as the snow melts in the western mountains, like crocuses do in the Alps. The strange green-flowered Verartrum viride is a medicinal plant of woodland glades and the various Camassia species, whose flowers range from white to purple, have edible bulbs.

Many of the wild flowers of the temperate regions of North America have come to enrich the gardens of Europe, and among them are several beautiful members of the evening primrose family. Oenothera missouriensis, a low, almost creeping plant of dry regions, is known as the glade lily, but this common name has not crossed the Atlantic to Europe. Both clarkias and godetias are American natives and so is the bergamot and the gay gaillardia, whose red and yellow flowers caused it to be known as fire wheel or Indian blanket. The best of the trilliums or wake robins are also American and the native species of golden rod and Michaelmas daisies, phlox, heleniums, rudbeckias and the spiderwort, which are widespread throughout large areas of both Canada and the USA, have contributed enormously to the gay appearance of English herbaceous borders.

The autumn colouring of American woodlands is famous and among the many shrubs and trees which contribute to the splendour of the Fall are several kinds of dogwood, notably Cornus nuttallii and Cornus florida. These also have a spring display of large white or rosy red bracts surrounding clusters of small greenish-yellow flowers. The diervillas and the flowering currant, the false acacias, including the beautiful rose acacia, the pretty white flowered shad bush and the catalpa or Indian bean tree are all American shrubs and trees. The swamp rose and the prairie rose bear a close resemblance to the wild dog rose of Europe, but have rather darker flowers.

Both the vast grass prairies and the arid desert regions to the west have a character all their own, very different from the rest of the North American continent. As the altitude increases the prairie becomes a high plateau and the grass gives way to the so-called sage brush, or rabbit bush. These are tough, drought-resisting shrubs mostly of the genus Artemisia, with grey-green or purplish-grey leaves and small yellow or brownish flowers. In Arizona and New Mexico cacti and other succulent plants begin to appear, and enormous areas of the Sonoran desert are covered in creosote bush (Larrea divaricata), which after the spring rains bursts out in bright yellow, twisted flowers. This shrub, which reaches five or six feet in height, has a strong resinous smell and is a host plant of the lac scale insect, whose excretions are collected and used not only as a glue or water-proofing material but also in Indian medicine. The ocotillo (Fouquiera splendens), is another Mexican desert shrub whose tall, green and thorny stems carry tufts of scarlet flowers in early spring. The tiny leaves only appear for short periods after rain.

The agaves, magueys, or century plants, are typical of south-western North America. Over three hundred different species are known and most of them are native to Mexico. It is a myth that they only come into bloom once in a hundred years, although it is true that most agaves die after flowering. The age at which they flower depends on the climate and the soil, as well as on the species, but it may be anything from eight or nine years to 20 years, but seldom longer. An agave 50 years old would be unusually ancient. The flower stalk, except in the very small species, is always tall and may either be branched like a candelabrum as in Agave americana, which is so familiar round the Mediterranean, or it may be a single spike as in Agave utahensis. The rather small flowers are either yellow or white, but occasionally dark red. Many agaves furnish fibres as well as sap, which is either used fresh as aguamiel, or fermented to produce alcoholic drinks like pulque or mezcal.

The yuccas have a much longer life than agaves and some of the woody species, which grow 20 feet or so in height at the rate of only an inch a year, may well be two or three hundred years old. There are only about 40 different kinds, and all of them have creamy flowers and rather narrow pointed leaves. They too yield fibres as well as soap substances and the flowers are often eaten both raw and cooked.

The Mexican cactus desert is unique in the world. It displays innumerable cacti like the giant saguaros and organ-pipe cacti, numerous flat-pad opuntias and the tree or shrub-like chollas or Teddy-bear cacti. Many different barrel cacti and mammillarias are also found here, which vary in size from quite tiny prickly balls to gruesomely spiny and massive plants as tall as a man. These huge old ‘barrels’ are known as compass plants, because they are always tilted towards the south west and so give some guidance to travellers trying to make their way through the desert, as well as providing an emergency supply of liquid.

Among the more gentle flowers of Mexico are the dahlias, the colourful zinnias, and the red cardinal sage, Salvia fulgens. The brightly spotted tigridia and the creamy-white zephyr lily (Zephyranthes longifolia) are two other natives, and there is a charming little annual (Baileya multiradiata) known as the desert marigold or paper daisy, whose golden flowers more or less dominate the desert landscape during the summer season.

Columbine

Aquilegia flavescens

Family Ranunculaceae

Columbines are not confined to America but occur both in Europe and Asia as well, and have long been cultivated as garden flowers. They are very dainty and graceful, and the way the flowers hang nodding on the stalks adds to their charm. Several of the American columbines have longer spurs than those in the Old World, and the yellow and crimson colouring which is now found in the improved garden varieties is also derived from the American species. This beautiful yellow columbine is a native of Canada and the famous Aquilegia caerulea, with flowers of lavender and cream, is the floral emblem of the State of Colorado.

Matilija poppy

Romneya coulteri

Family Papaveraceae

This Californian flower with its finely pleated snow-white petals and the big golden boss of stamens is even more beautiful than the brilliantly coloured oriental poppies which are more familiar in Europe as garden plants. The blue-green foliage sets off the flowers to perfection and they remain open for several days. It is a perennial, grows about four feet high and is found wild in coastal areas and in some of the canyons in the Santa Ana Mountains. It resents root disturbance and can only be transplanted when young.

Calico bush or Mountain laurel

Kalmia latifolia

Family Ericaceae

Pink calico has gone out of fashion but this enchanting North American evergreen shrub, with its clusters of parasol-shaped flowers, is still considered a beauty. The curved stamens form the spokes of the parasol and the anthers are at first tucked into pocket-like folds in the petals. When bumble bees and other insects blunder into the flowers seeking honey, the stamens spring up towards the centre, dusting their furry bodies with pollen. The kalmia was named after Pehr Kalm, a Finnish botanist who travelled in North America in the middle of the eighteenth century.

Adam’s needle

Yucca whipplei

Family Agavaceae

Yuccas are very typical of the southern States and Mexico and they are also found wild in the West Indies, growing in rather dry localities. Unlike agaves, yuccas flower regularly and the plants do not die after producing their spikes. The large flowers are half closed in daylight but at night they open fully to allow Pronuba moths to enter and gather pollen. These moths then fly on to other flowers where they lay their eggs, deliberately spreading the pollen to ensure the development of the seeds on which their caterpillars feed.

Shooting star

Dodecatheon pauciflora

Family Primulaceae

Except for the protruding anthers, the flowers of the shooting star are very like those of a cyclamen in shape. There are about fifty different species, all of them native to North America. They range from Alaska right down to California and are found in the eastern States as well. Most of the plants have flowers which are purplish or mauve’, occasionally crimson or white, with a yellow edge to the coralla tube. They vary in size and leaf shape and the number of flowers borne on the stalk, which in the taller species may reach a height of two feet or so. These are woodland plants, preferring a semi-shady position.

Beard tongue

Pentstemon rupicola

Family Scrophulariaceae

There are about 250 different Pentstemons and all but one, which grows in Russian Asia, are natives of the United States. They range from creeping mat-forming shrubs to small bushes and quite tall herbaceous plants, and are often so floriferous that the leaves are almost hidden when they are in full bloom. The flowers are more or less tubular, often with a prominent lip. Many of the species are excellent garden plants, although not always quite hardy in Britain, and there are also a great number of garden hybrids.

Lewisia tweedyi

Family Portulacaceae

All of the Lewisias are indigenous to North America and twenty or so different species are found among the mountains of the West, where they grow in rock crevices and in well-drained stony ground. L. tweedyi grows on Mount Stuart in the State of Washington and has larger flowers than most of the others. It makes a beautiful rock garden or alpine house plant and has a thick tuberous root. One member of the group, L. rediviva, was used as a food plant by the Red Indians, although its roots have a strong bitter taste. None of the Lewisias will tolerate lime so they must be grown in neutral or acid soil.

Blue-eyed grass

Sisyrinchium bermudiamun

Family Iridaceae

Sisyrinchiums are found both in North and South America in a hundred different forms. The pretty blue-eyed grass grows wild in the woods of the eastern States, from Florida up to Quebec in Canada and is also found on the islands of Bermuda and in western Ireland. It is a popular garden plant and quite easy to cultivate. The prairie blue-eyed grass, Sisyrinchium campestre is a native of the central North American plains where it grows among the grasses in full sunlight. It is taller than the previous species and the flowers are of a clearer blue.

Magnolia

Magnolia grandiflora

Family Magnoliaceae

The magnolias are a very ancient group of plants, and fossil deposits show that some five million years ago they were more widespread than they are now. The most splendid of the evergreen species is this American magnolia whose large glossy leaves are a rusty brown on the underside. The huge white flowers, measuring eight inches across, have a lemon scent and are the floral emblem of Louisiana and Mississippi. The tree grows wild in damp, rich soil right across the southern States. It needs a warm climate and although it can be grown out of doors in southern England it is usually planted against a wall for protection.

Poinsettia

Euphorbia pulcherrima

Family Euphorbiaceae

There are over 2,000 kinds of Euphorbia scattered throughout the world, varying tremendously in appearance from spiny cactus-like plants, to shrubs and quite small herbaceous species. The poinsettia, a native of Mexico and very familiar as a decorative plant, is grown in quantity for the Christmas trade. The scarlet leaves are not petals but only coloured bracts surrounding the cluster of small greenish yellow flowers. The poinsettia can only be grown out of doors in tropical climates and in the West Indies it is used as a hedge plant. Like most Euphorbias it contains a milky latex, which oozes out if the stems are cut.

Indian paintbrush

Castilleja miniata

Family Scrophulariaceae

These interesting plants are found over a wide area of North America, especially in the west, and mainly in open country among grasses. They have green leaves, but are nevertheless semi-parasites which derive extra nourishment from the grass roots. The ‘paintbrushes’ are single stemmed, and the bright colouring is not derived from the flowers but from the bracts and upper leaves, which make the plants very conspicuous. The flowers themselves are usually yellow or greenish and the colour of the bracts varies in the different species. Because of their parasitic habit they are very seldom grown in gardens.

Hedgehog cactus

Echinocereus engelmanni

Family Cactaceae

The cactus family comprises some 2,000 species, most of them natives of the arid desert regions of Mexico, Arizona and southern California. These plants have a remarkable ability to survive drought by storing water in the tissues of their leafless stems and they are protected against grazing animals by their fierce spines. The plants themselves are ugly and forbidding, but when the flowers are produced they are often large and beautiful. In some cases the flowers last only for a single day or night, but other species open their blooms for several days in succession, closing them in the evening at sunset.