How Succulents Developed

The story of succulents begins nearly fifty million years ago m a time called the Eocene epoch. A great waterway stretched from the Gulf of Mexico to the Arctic then, i he Mediterranean lay deep in Asia. A hundred nameless seas covered our great deserts and mountains. Along their shores vast forests teemed with the beginnings of modern plants and animals Everywhere the climate was subtropical moist, abundant. Life was easy.

Then gradually the earth began to change. The ancient seas slowly retreated, revealing great new masses of land, Deep tremors shook the fields and forests, thrusting up great mountain barriers, the Rockies, the Sierra Nevadas, the Cascades— the Alps, Carpathians, and Pyrenees. A hundred volcanos formed the Andes. A new world began to take shape, a different world, the modem world we know today.

As the face of the earth changed, so did its climate. The year-round warmth and rains of the Eocene jungle gradually disappeared. In their place clearly marked seasons and climatic belts developed. There was a spring and summer now, a fall and winter. There were the Arctic and Antarctic, the tropics and Temperate Zone, Where there had been nothing hut endless steaming jungle over much oi the world, there were now high mountains, fertile plains, and endless deserts.

As the mountains rose in many parb of the world !hey gradually cut off the moisture-laden an blowing in from the seacoasts. And where the rain clouds could no ¡onger cross the mountain barriers, the lands beyond the ranges burned by day and froze by night What little rain they got reached them by winds coming from oiher routes, or in brief summer thundershowers formed out of the hot air rising :"rom the desert floor, JejHE

Ai this time, too, a permanent belt of high atmospheric pressure developed extending some thirty or thirty-five degrees on each side of the equator. In this belt crratic winds and frequent calms prevented much rain from forming or falling* And from this lack of rain the world of the desert evolved—a very special world, with its own geography and i ifd H

climate, its own plants and animals, its own rhythm and way of life. In this way the Great Basin of North America was formed; the deserts of Mexico, Peru, Chile, and Argentina; the vast hinterlands of Asia and Africa. Gradually, very gradually, much of the Eocene world became a wasteland.

As wind and water eroded the rising mountains, the valleys below filled deep with earth and rock, J fie deserts stretched from mountainous plateaus lo flat sandy plains. Wlierc the wind was strong, the moving sand carved fantastic shapes in the rocks or piled high in rolling dunes. Where it sometimes rained» the water dissolved the mineral-rich earth, leaving behind great salt lakes.

Then new rivers rising beyond the desert entered the drying landjustasit was lifting froinits ancient bed. Filled with sand and rock, the grinding torrents cut through the earth, forming deep canyons, for there was no rain here to wash over the cuts—to widen them gently into broad river valleys. The sheer canyon cliffs, the great salt lakes, the dunes, the cactus-drought made them all.

Before the drought came, the Eocene fields and forests abounded with plants—remarkably modern plants, complete with roots, stems, leaves, flowers, and seeds. They were of many different families, forerunners of our lilies and oaks, gourds and palms. Iji the warm, moist climate they grew rampant. -

Then came Lhe change. It did not happen in a day or a year: it happened gradually. Some say it took twenty million years.

At first the year-round warmth and rains were interrupted for-only a l.ttlewhile. The plants in the fields and forests look u rn their stride, just as they would in our gardens today. They slowed Ihe.r growth, branches shriveled a little, a few leaves wilted and fell. Soon the "bad spell" was over and they flourished again as strong as ever. But when the waters began receding in the ancient lakes and seas, when the rising hills became great ranges shutting off moisture from the coast -

how the wastelands were formed

the dwindling plants struggled desperately for life, tried to live out a few more weeks of drought, then a few months, then a year. Before the rains came again, most of them died.

Only a few survived. By some miracle they kept pace with the drying land, changed themselves endlessly, waited pan-emlw and in the end inherited the wastelands of the world. As a group these plants are called xerophytes (ze'-ro-fues), from ihc Greek words meaning "dry plants/' They include nut only such curiously adapted desert dwellers as the yucca, ocotillo. palo verde, mesquite, and sagebrush; but that remarkable group of plants welcall succulents.

Dry Plants and Succulents

We do not know whether these xerophytes remained in the drying land throughout the whole process of their evolution, changing and adapting themselves lo become desert dwellers over a period of twenty million years, or whether the wastelands became extinct of ail life and these plants were hardy pioneers who ventured gradually into the barren lands from more favorable surrounding areas. But we do know they managed to survive the scant rainfall, the long periods of drought, the intense heat and cold of the wastelands by using one or more of these three devices: economizing, lying low, and storing.

First, all xerophytes learned to economize. The broad lush leaves or the Eocene jungle which transpired untold gallons

7,cr ®to ** day were reduced in size; were covered with wa*, resin, or hair; or rolled until they became almost hke needles. The stomata. or leaf pores, were reduced m number. Stems and branches often became thin, hard, and

K? S3P bcc3me thick' milky. All this was done

~ ^ evaporation, some xerophytes learned to lie low. They clung to the introducing slt ( llen is shadow of rocks and such vegetation as there was. They buried themselves in ihe long months of drought and became seemingly as dead and dry as dormant seeds.

And, finally, some learned to store—to come to life quickly at the first sign of a shower, to greedily drink with wide-spreading rooLs even the lightest dew. And to store this precious moisture some developed great tuberous roots, and others thick, fleshy leaves, stems, and branches. It is these last— xerophytes which learned to store water in greatly enlarged leaves, stems, and branches—that we call "succulents."

It ¡s very difficult to draw a sharp line of distinction between succulents and other xerophytes* or xerophytes and ordinary plants, In many plant families we can find a wide ran^c of drought resistance—from soft, lush, tropical plants requiring an abundance of moisture through every degree of drought resistance until we rcach true succulents» Thus in the Lily family we have the tropical Bermuda or Easter lily, the relatively drought-resistant asparagus, the xerophytit yucca and its relatives of our Southwest, and the truly succulent aloes of South Africa—and every conceivable gradation in between.

We do not know why plants belonging to the same family became simple xerophytes in one place, as the yuccas in our Southwest, and succulent in another, as the aloes in South Africa The tendency toward succulence seems to have been inherent in certain members of a family and noi in others. Then, too, the peculiar condmons of geography, climate, and development no doubt determined the type of response each plant was to make.

Actually succulence in plants—the ability to store water-is a relative thing. All plants store some water in their roots, stems, and leaves to meet days and weeks of hardship. Some even show exceptional ability to store moisture in bulbs, rhizomes, and tubers to withstand months of dormancy, But in the succulents this ability to store moisture against even years of drought is so highly developed as to be unique. While other xerophytes evolved thinner, harder, drier stems and leaves to resist the endless heat and thirst of the wastelands, the succulents made these parts larger, thicker, fleshier to serve as storage spaces for water. It is no wonder they have been called "camels of the plant world."

Where Suecu/enfs Grow

Succulents arc found almost anywhere in the world today where plants have difficulty getting and keeping water. Specifically there are four geographical areas that are the natural habitat of succulents, I hey might be termed the desert, alpine, jungle, and shore line.

The first and most important of these are the great deserts and semi-arid brushlands of North and South America. Africa, and Asia. Here intense heat, sandy soil, lack of rain-fail. and drying winds have given rise to the largest natural habitai of succulents. But it is important lo know that not all the deserts of the world have native succulent plants. Extreme deserts such as the Sahara, Gobi, and Great Sandy Plain of Australia afford so little moisture that few if any succulents have !>een able to grou in them. Here we find only xerophytic tbornbushes and low annuals growing in the shifting dunes. Other desert areas often lack succulent plants too, because these wastelands have been formed too quickly to allow for the gradual evolution required to develop succulents, or the xerophytic plants in the area have had no inherent tendency toward succulence. But in all other desert areas where rainfall exceeds a very few inches annually and climatic conditions are not too extreme we can expect to find succulent plants, - m IT

_ i, succulents are also found in the tropical ram forests of Central and South America, where, although rainfall is abundant, certain trce-dwelling cacti have developed succulence they get scant moisture from the hits of moss and bark in which they are rooied high in the trees.

Another important area where succulents may be found is the high mountain regions of the world, Here many plants have become succulent because intense cold, strong winds.

and a loose, rocky soi! have made getting and keeping water difficult.

And, finally, succulents are found on the shores of salt lakes and seas, where the brackish ground makes the absorption of water difficult for plants. In all these places the struggle over millions of years for life-giving moisture has changed many familiar plants into highly specialized succulent forms.

The Patterns of Survival

Despite their amazing variety and number all succulents may be classified in one or another of two groups—leaf succulents or stem succulents. Plants belonging to the class known as monocotyledons, such as the lilies, usually took on (he form known as leaf succulence, "he leaves of these plants were greatly thickened and crowded into a cluster or rosette, either with or without a fleshy or woody stem. Plants belonging to the class known as dicotyledons, such as the cacti, took in addition still another form. With them the stem was greatly enlarged to serve as a storehouse for water and to carry on the vital functions 03 photosynthesis, and the leaves were either much reduced and short-lived or dropped altogether.

But much more important than the outward changes and forms these plants took are the immense internal changes they had to undergo before they could become succulents. Their main problem was getting and keeping moisture more efficiently And they solved it in a thousand ingenious ways.

First, they had to get water. Rainfall in the wastelands was seasonal and brief. The succulents had to drink thirstily and well for a few hours or days each year, and then wait months before they could slake their thirst again. To gather this precious moisture they developed a fantastic variety of root systems according to the soil and climate in which they lived.

Succulents living in areas of extreme drought often developed great tuber-like roots to store water between rains. Others in s he rocky foothills and mountains sent their roots deep into the moist substrata underlying the surface. Others on the open plains developed a fine network of roots spreading for yards about the plant but only an inch or two beneath the surface in order to catch the lightest dew. Actually the roots of most succulents are so extensive and interlaced that if these plants were turned upside down the sparse and scrubby wastelands they inhabit would look like impenetrable jungles.

The next problem after the succulents soaked up their water was to keep it. They had to effectively prevent the excessive evaporation which the bright sun and drying wind of the desert could cause, for all plants in order to live must transpire a remarkable quantity of water through the pores in their leaves and stems. When we consider that a grass transpires its own weight in water daily, a stalk of corn more than a gallon a day, and an apple tree two thousand gallons in a single growing season—we can see the vital importance of curtailing this evaporation in succulents When a succulent plant receives as its whole yearly supply as much water as a lush jungle plant expends in a single day, it obviously must hoard this precious moisture or die.

Like other xerophytes. the first and most obvious thing the succulents did was to economize. They shortened their leaves and stents, took on a more compact form to present less evaporating surface to me drying sun and wind. In the leaf succulents the plants grouped their leaves in light clusters, one leaf overlapping another like shingles on a roof, protecting each other from the drying elements. The stem succulents reduced their leaves rolling them into needle-;ike projections: or kept them only briefly during the short growing season


Stem succulents

Leaf succulents

FVotective devices how succulents developed and discarded them at the first sign of drought; or dispensed with them altogether to become perfect stem succulents, never showing a leaf except in the embryo stage.

To further reduce their evaporating surface many stem succulents took on a spherical form, a form which could hold the greatest amount of moisture with the least surface exposed to the drying elements. But many of these stem succulents carried the economy of form and loss of leaves too far, for they needed the gieen assimilating surfaces of leaves and stems to manufacture food by photosynthesis. To take the place of the disappearing leaves the succulent stems themselves became greener, fleshier, and finally took over the vital processes of manufacturing food. But although the light of the desert is bright, many of these stem succulents still could not afford to lose the broad surfaces of their leaves entirely. So we find that where the leaves were formerly attached the stems of many succulents developed nobs or nipples, wings or ribs, to maintain proper assimilation of light and manufacture of food. These ribs also permitted the plams to spread themselves accordion-like to take up a greater volume of water when it was available and to contract when there was none.

A second means ol curtailing evaporation was to drastically reduce the size and number of stomata, or pores, in the leaves or stems through which water could transpire. Since even a common geranium has two million of these pores in a single leaf, the necessity for reduction was obvious. Once the pores had been reduced in size and number, they were sunk lower in the stems and leaves and further shielded by wax, resins, spines, and hairs developed by the plants. Most succulents also developed a greatly thickened outer skin which helped protect the plants and reduce evaporation further.

A third means of reducing evaporation, held in common with other xerophytes, was the clever expedient of lying low. Many succulents learned to bury themselves almost entirely in the soil, to expose as little of themselves as possible to the outside world. Others learned to cling desperately to the shade of rocks and other desert plants.

But as the supply of water the succulents could take up in any rainy season was small, and that which they gave off in the long periods of drought even less, the whole internal chemistry of succulents changed. Since plants can absorb food from the soil only when it is dissolved in water, and since the intake of water in succulents was never very great, the assimilation of food was slowed down tremendously. This explains why succulents are relatively slow-growing, slow-living plants.

And as the chemical processes in the plants slowed up, there appeared a greater tendency toward the accumulation of by-products. Some of these were seemingly useless to the plant, as calcium oxalate, which crystallizes in enormous quantities in the cells of some cacti. Other by-products, such as wax, deposited on the outer skin served the useful purpose of reducing evaporation and partially shielding the pores It is even possible that the elaborate formation of stiff hairs, bristles, and spines in desert plants is actually the result of too great accumulations of silicon, an element useless for nourishment but giving rigidity to plant parts. This silicon, concentrated in modified leaf stalks, branches, and flower stems, produces the characteristic armament of many succulents. Certainty these teeth and spines not only serve to protect the plants from browsing animals, bui often form a latticework to shade the body of the plant and further reduce evaporation.

Once the) had adapted themselves to getting and keeping water, the succulents had to make further changes to protect themselves. Since thev were the best source ol food and mois ture for herbivorous animals in the wasteland, they had to protect themselves or be eaten. Some, liJce the cacti, agaves, and aloes, armed themselves with sharp spines or teeth. These

weapons were always on the most projecting pans of the stems or leaves, and the lende heart of the plant was usually sunk deep inside their protective cover« Others, lacking this armamen:, developed a strong, thick skin, like many of the gas-terias. Some, like the sedums and epiphyllums, grew in rocks or trees out of reach. Others, such as the lithops, camouflaged themselves, mimicking the texture and color of their surroundings so that they could not be seen. Still others, like the windowed plants, buried themselves in the soil almost entirely, admitting light to their interiors through exposed "windows" in their leaf tips. And, finally, some protected themselves with repulsive or poisonous juices, as the quinine-flavored dudleya.

To further insure theu survival in the wilderness nature designed succulents so that they could not only propagate themselves by seed, but also, in many species, multiply themselves spontaneously by fallen leaves, branches, or shoots. Wind, rain, or a blow from anything that passed could easily scatter the fleshy leaves and shoots, and because they carried iheir own moisture lhey could quickly root on dry ground, Other succulents, like the bryophyllums, formed tiny well-developed plants on their flower stems or leaves which fell to earth ready to grow. Even the green fruit of certain cacti can make a plant if they touch the soil. Of all plants the succulents are perhaps most efficiently designed by nature for easy propagation.

In a thousand different ways the succulents adapted themselves to a thousand different environments. But it was by no means a conscious adaptation. They did not perform any of these miracles deliberately. The process was the long and cruel selection of nature in which only the fittest survived. And all these forms that remain today are simply the more successful experiments io that endless process of trial and error we call evolution.

Though they came from many different families, with different forms and habits, all these plants under the same pres-

sures of necessity made similar changes in form, and in the end came to resemble each other. Before they could exist in the harsh climate of the wastelands, these lilies, amaryllids, daisies, and milkweeds had to adapt themselves to get and keep moisture more efficiently. Luckily they could adapt. For hidden in their stems and leaves was the quality of succulence. the ability to store more and more water to meet the ever lengthening seasons of droughl. As millions of plants perished about ihem for lack of this gift, the succulents lived on. But in order to live they had to change endlessly The broad leaves of the jungle grew smaller in each generation, grew thicker, or sometimes disappeared altogether. The rank jungle growth became shorter, heavier, changed in a thousand ways 10 conserve precious moisture. Each group o; survivors, in its own way, in its own time, changed to meet the pressures of its own locality. Shaped by a hundred new climates, isolated by great mountain ranges, rooted in an endless variety of soils—the succulents took on the myriad forms we know today.

chapter two in all the world no oiher plants are wonderfulls varied in form, so beautiful in flower, so remarkably adapted to life as have been so thoroughly misunderstood.

How often we call any plant with an odd form or spines a cactus, no mailer if u belongs 10 the Lily or Amaryllis family, the Daisy or Milkweed clan. How often we think of succulents as strange plants—half ugly, half comical—never to be compared with our pet roses and orchids, azaleas and camellias. And because of our blind prejudice we miss one of the most interesting and beautiful experiences the world of plants has to offer.

Understanding succulents is like understanding people. They seem odd and different until we learn something about ihem—where they came from, how they developed, how they were meant to live and grow. Then we begin to see beauly where there was only strangeness; we begin to feel a strong attraction where there was onl> fear and indifference before»

Lure Succu/enfs rx

It is difficult for those who hâve not felt the lure of succulents lo understand the powerful attractions I hey excri on those who love them. First, succulents offer variety to satisfy even the most insatiable gardener. They range in size from plants scarcely larger than a thimble to giants towering fifty feet high and weighing tons. Their forms are infinite.

But many gardeners are not interested in plant forms alone, they want flowers. Here too succulents will not be found wanting. Among ihem we can find the largest flowers on earth and some of the tiniest, blooms of such incredible textures and colors as to put our pampered orchids and camellias lo shame. And the succulents offer color not only in their flowers, but in their stems and leaves, so often tinged wiLh an iridescent bloom of frosty white, rich purple, or red. Even the feared teeth and spines intrigue us by their varied colors and intricate patterns,

Bui perhaps the thing that really seals the attraction between succulents and those who love them is the quiet lessons they teach of endurance and faith in life. How well they exemplify the virtues of patience and economy, the wisdom of lying low and rolling with the punches, of storing within ourselves those vital resources we will need in limes of adversity Succulents are strong plants, and they make those who grow them strong.

In our first chapter we have spoken of succulents becoming 'adapted" to drought, of becoming ''adjusted" to their environment, Bui we did not use those words in the sense in which sociologists so often use them today. Unlike people, succulents have not lost either their individuality or strength in meeting ihe demands of their environment. They have not simply made the most of life, as sociologists tell us we must, but the best. The difference is tremendous. These plants have met adversity and change with strength, not submission. They arc not simply "adjusted" to their environment — they are triumphant id it.

Five Famous Fallacies

Before we can either see or appreciate the value of succulents, however, we must dispose of our basic fears and prejudices. There are perhaps no more persistent and ridiculous falsehoods in all the world of plants than these five famous fallacies concerning succulents,

I. All succulents are cacti. As we have seen, the Cactus family is only one of nearly thirty plant families which have succulent members. To be sure, il is one of the largest and best known —but it is not the only one. The beginner is perhaps understandably confused, because some succulents in other plant families sometimes resemble cacti very closely. Bui when one is in doubt, it is always safer to refer to these plants by the general term succulents rather than by the very specific family name Cactus.

2 All succulents grow in the desert. Although Ihe deserts of the world contain the largest number and variety of succulents, not all succulents are desert dwellers. They are also found in tropical jungles, on high mountains, and by the shores of salt lakes and seas.

3. All succulents grow infull blazing sunlight. The notion that succulents grow only in full sunlight is incorrect. Many succulents. even desert dwellers, prefer to grow in the partial shade of rocks and other plants rather than in the bright sun.

A. AH succulents grow in pure sand. It is obvious from their wide variety of habitats that succulents grow in many different kinds of soil. Even the so-called pure sand of the deserts is far richer than one might suppose, as can readily be seen where portions of desert lands have been reclaimed for farming by irrigation.

5. All succulents can live without water. Although the succulents can probably grow with less water than any other

As dramatic-accent plants in the home or garden succulents are unsurpassed Agave aitenuata (ajiove) and Echeveria gfauca (below) are combined here in a ''strawberry jar" planter to make a striking study in gray.

understanding succulents group of plants, they must have a reasonable supply in order to continue life. This is dearly demonstrated hv the fact that very extreme deserts, such as the Sahara, cannot support succulents simply because there is not enough rainfall.

A Problem and a Paradox

The fact that succulents are so well adapted to drought and hardship has led many gardeners to one or another of these false conclusions: that better care will necessarily improve the plants, or that lack of attention is the secrct of successful succulent culture. Actually succulents often receive very particular care in nature, especially where soil and drainage are concerned, and too much kindness with water and fertilizers usually means sure death to them.

The problem in growing succulents is a strange one. Everything detrimental to them seems to be eliminated from our homes and gardens. They don't have to put up with dry soil, scorching sun, lack of water, or browsing animals. Yel there is a problem. Under cultivation these marvelously adapted plants often suffer Their armor is useless; their compact form, juicy leaves, and thick skins are more a hindrance than a help. They are fitted with equipment they no longer need but cannot change. So il is up to the gardener to compensate lor ihis paradox.

Success with succulents requires a good deal of observation, common sense and, above all, an understanding of where they came from and how they were meant to live and grow. Bui this is more easily said than done.

An Embarrassment of Riches

The collector of succulents is faced with an embarrassment of riches. In the Cactus family alone there are more than (wo thousand species, and the caeti are but one family in nearly thirty containing succulent plants. Fortunately of the tens of thousands of succulents known probably less than half have ever been cultivated by collectors. And of these, many, many hundreds are so rare, difficult to grow, unwieldy, or uninteresting that they are obviously useless to the beginner But ihere still remain several thousand species and varieties from which we might choose. How can we decide which are the most beautiful, most interesting, most desirable to have in our collections?

Of course thai question is not easily answered. For the selection of any plant depends on the needs and tastes, interests and purse of the individual gardener. But aside from that there are certain succulents that stand out from all the rest, i he\ are llie most popular, readily available, easily grown, and useful kinds in their respective families. They have stood the lest of time and universal appeal. The beginner should know and grow these varieties first, and ihen move on to others as his skill and interest develop.

The chapters which follow attempt to suggest some of the *4besf kinds in each family. But they are admittedly incomplete, not because the plants listed in them are not among the best, but because many who read them will wish to add a few more kinds in every family according to their individual tastes and experience Of course that is to be encouraged, just as the hope that future years will see the arrival of many new succulent varieties that will eclipse some of these.

chapter three chapter three

It is fitting thai any discussion of succulents begin with the Cactus family, not only because it is one of the largest and best known but because it illustrates in a very surprising way the evolution of all succulent plants.

Were it not for a strange coincidence, we might never really know how succulents evolved from the Eocene jungles to their present way of life. Deserts, unlike marshes or lakes, are not very favorable to the preservation of fossil plants, So it is not surprising that the ancient forerunners of the succulents disappeared without a trace millions of years ago. But, as if to compensate for this lack of fossil evidence, nature has given us something infinitely more exciting. In the Cactus family today there is a remarkably complete sei of living forms which illustrate step by step how this group of plants evolved from primitive, leafy jungle plants to highly specialized desert dwellers.

There exists in the jungles of the West Indies today a clambering tropical shrub or vine called a pereskia, which is, to an uncanny degree, the living image of the Eocene ancestor from which all our cacti evolved. And that is noi all. We can

also find in other Living members of the Cactus family every gradation in the evolution of succulence from the lush, tropical pereskia to the most hard-bitten desert dweller. So instead of looking at fossil remains in a museum case we can actually see growing before our eyes the whole pattern of evolution in the Cactus family from Eocene jungle to modern desert succulents.

What Are Cacti?

The Cactus family is not clearly related to any other, though some have suggested a kinship with the portulacas, mesenv bryanihemums, myrtles, or even roses. It contains over two thousand species, virtually all of them full stem succulents. Although they differ widely in form, si2e, and habitat, all us members can be recognized by five common traits.

First, all cacti have a unique cushion-like structure on their stems and branches called an areole (a' ree-ohl). Each areole has two growing points, or buds, the lower one generally producing spines and the upper one producing new branches or /lowers. Second, cacti are perennial: that is. they require more than one season to mature, and they do not die after flowering. Third, cacti usually have wheel- or funnel-shaped flowers with an indefinite number of sepals and petals, and the ovary or friiit is always formed below the flower. Fourth, the cactus fruit is a one-celled berry with the seeds simply scattered through it. Fifth, all cacti belong to that class of flowering plants known as dicotyledons (dy-kot'-i lee'-dun)- Their seeds always produce two embryo leaves, or cotyledons, on germination Any plant having all these traits js a eacius. If it lacks even one it is something else.

The Cactus family is native only to the American continent, ranging from the Arctic Circle to Patagonia. But its real home lies somewhere in the middle of that vast stretch, in the great American Southwest and northern Mexico Here cacti are the outstanding feature oi the great deserts and wastelands of California, Arizona, New Mexico, Texas, and Sonora,

As one moves south, the number and variety of cacti decrease, until in tropical Central America and the Caribbean the desert species give way to curious tree-dwelling cacti. Below the tropics, in South America, the number of desert species rises again through Brazil, Bolivia. Paraguay, Uruguay, and Argentina, but never in such bewildertng variety as in Mexico and the Southwest. Across the Andes, the deserts of Chile and Peru offer a large and unusual cactus population.

History and Nomenclature

Cacti were unknown in Europe before the discovery of America. When the early Spanish and Portuguese explorers landed in the New World they were amazed to find these strange plants, for they were not only a remarkable feature of the landscape, but were cultivated by the aborigines for food, limber, drugs, and drink.

It is not surprising that they took these plants, particularly the edible Prickiy Pears, back with them first to the Canaries A/ores, and Madeira Islands; then Portugal Spain, and the whole Mediterranean. From there the Prickly Pears spread to Egypt. India, and other parts o southern Asia, becoming an important food in many areas, a serious pest in some, and a remarkable curiosity in others.

The first cacti thai reached Europe must indeed have seemed plants from anolhei world The date of their introduction is not known, though the explorer Coronado mentions them in his account of the New World in 1540. But in 1597 we find pictures and descriptions of two cacti in England. Gerarde in his book The Herhail or General! Historte of Plantes is completely astounded by the common Prickly Pear, which he calls Ficus Indica. or the prickly Indian Fig Tree. And of a second species, the Turk's Cap from the West Indies, he writes:

Who can but inaruell ai j he rare and singular Workmanship which the Lord God almightie hath shewed in this thistle, called by ilit? name or A/eto-cflrdiiw Echinatus T1}ls knobbic or bunchie masse or lumpe is strangely compact and context togiiher, containing in it sundry shapes or formes, participating ot d Pcpon or Melon, and a Thistle, both being incorporate in one1 bodie; which is made after the forme of a cocke of haie ...

With such remarkable descriptions, it is not surprising that the number of cacti in Europe increased rapidly, Bui with them stuck the idea that they were somehow like thistles. When Linnaeus in 1753 listed twelve of these plants in his Species Plamarum he grouped them all under the name Cactus, derived from the Greek kaktos, which is the ancient name for a r prickly thistle or cardoon, Thereafter this family of plants has been called the Cactaceae (kak-tay'-see-ee), single plants cactus (kak'-tus). more than one plant cacti (kak'-tie), rather than cactuses.

Through the eighteenth century and into the early part of the nineteenth interest in cacti grew tremendously as new planfs were introduced to Europe. Gerarde's simple classification of Indian Figs and Melon-thistles and Linnaeus's grouping of the dozen plants he knew as "Cactus" could hardly begin to describe the scores of strange and varied plants that captivated Huropean gardeners. Many botanists tried to put the evergrowing list of cacti in some kind of order but it remained for Karl Schumann id publish the first coherent classification of the family in his Monograph on the Cactaceae in 1898.

Schumann divided ihe Cactus family into three tribes in the probable order of their development; the Pereskia, the Opuntia. and ihe Cereus. But theie were sliil far loo many and varied cacti in each tribe for easy recognition, so Schumann divided the three tribes into twenty-one smaller groups called genera (the singular is genus). These genera, groups of plants in each tribe having certain obvious structural characteristics in common, contained in turn the thousands of individual kinds of cactus plants, or species. And these species in turn produced variants which are called varieties,

It may help to understand Schumann's plan, and the general method of scientific nomenclature, if we remember that the first part of a plant's scientific name is that of the genus to which it belongs, the second part, usually a qualifying adjective indicating what kind, is the species name; and, where necessary, a third part indicates the particular variety. Thus in the family Cactaceae, the tribe Opuntieae, we have the cactus Opuntia fragilis var. tuberiformis. Opuntia is (he generic name of the plant; fragilis its specific name, indicating the Fragile Opuntia, a particular kind; and iuberiformis. the varietal name, which tells us that this variety of Opuntia fragilis has tuberlike stems.

Although Schumann's system was widely acclaimed and adopted in Europe, new botanical explorations in the Southwest, Mexico, and South America after the turn of the century brought to light hundreds of cactt that could not be explained by his classification- After extensive research and exploration under the auspices of the Carnegie Institute, Dr> N. L Brit ton and J. N, Rose published a new and monumental American classification, The Cactaceae. in the years 1919 to 1923 Here ihey accepted Schumann's three tribes—the Pereskieae, the Opuntieae, and the Cereeae— but subdivided the last into eight subtribes, and the twenty-one genera into one twenty-four.

Since the publication of The Cactaceae new explorations have added many more cacti to the family, with suggestions for new classifications, subdivisions, and genera; but the basic work of Britton and Rost remains fundamentally sound and still the best guide to the vast and perplexing family of cacti. The brief survey of the Cactus family which follows is patterned somewhat after the Britton and Rose classification. But to simplify die recognition of cactus tribes and subtribes popular descriptive titles have been used suggesting the chief characteristics of each group, and only those genera and species of outstanding interest to the beginner are discussed.

The Leafy Cacti— The Pereskieae

The first tribe of the Cactus family contains its most primitive members, for they are actually common jungle trees, shrubs, or vines. They may be easily differentiated from other cacti by their sprawling woody stems, ordinary broad evergreen leaves, and clusters of fial wheel-shaped flowers borne on stalks. Members of this tribe have two kinds of spines coming from their areoles: straight for protection, and hooked for

The genus Pereskia (per-es'-ki-ah) dominates this first tribe of the Cactus family. There are some eighteen or twenty species of pereskia native to the West Indies, Mexico, Central and South America. In the tropics they are grown as ornamentals or hedges, and the olive-sized yellow fruit of its most popular species are prized as ltBarbados gooseberries."

Pereskia aculeate, commonly called the Simon Vine, is thai best-known species It is a clambering, shrubby vine to ten feel or more with broad, flat leaves much the same shape, size, and color as a lemon leaf The slender stems are first prickly, then develop long needle-like spines. Although sometimes difficult 10 bloom in cultivation, the clusters of fragrant, creamy-pink flowers are as charming as wild roses. A striking variet) with leaves variegated red, ap:icm, yellow, and green on the upper side, and red purple on the underside, is called P. aculeara var. godsejfiana.

For the collector pereskias are interesting as living examples of the kind of primitive non-succulent plants all cacti evolved from, and useful as understocks for grafting. Except in very favored localities the pereskias must be treated as tender plants for the home or greenhouse. They require rather large pots, abundant water in the growing season, and a minimum temperature above 50°K They arc easily propa-

th£ leafy cacti. pricmy pears, \SD chollas
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