How To Recognize A Cactus
( Originally Published 1942 )
IT is not considered necessary at this time to give a technical discussion of the groupings of plants. It is quite essential, however, for the reader to have a general understanding of the meaning of such group names as family, tribe, genus and species.
The family includes those plants which have in common certain characteristics which the botanist considers indicate a definite but rather distant relationship. The layman is often astounded to find that two such plants as the rose and the apple belong to the same family. It may be rather a shock to learn that the potato, the tomato and the tobacco plant are all members of the same family. There are members of the Cactus Family which differ quite as widely as these plants mentioned. There are other plants which have so much of the "cactus look" that the inexperienced collector may find himself greatly embarrassed when he discovers that his latest find is only some other thorny citizen of the desert.
All plants belonging to the Cactus Family have five characteristics in common, which are described briefly and simply as follows:
1. Each seed has two cotyledons. This means that the seed is composed of two halves like the bean. When the seed germinates, these halves, which are seed leaves, appear at the same time.
2. The fruit is a berry enclosing the seeds. This berry is one-celled having no cross membranes to divide it into sections as in the orange.
3. Spine cushions (areoles) are always present. In some kinds of cacti the spines re absent, but the cushions are usually armed with spines or with fine hairs that have barbs on the ends (glochids) or with both spines and glochids.
4. All plants belonging to the Cactus Family live year after year and for this reason are said to be perennial.
S. The flower is always attached to the top of the ovary or fruit.
Many plants have some of these characteristics, but they must have all of them in order to belong to the aristocratic family of Cacti.
The Cactus Family is divided into three groups known as tribes. The members of each tribe have not only the characteristics of the family, but they have other characteristics in common which set them apart from the rest of the family.
One of these tribes, the Pereskiece, is composed of plants native only to the tropics. They have broad flat leaves. The flowers are borne on stalks, and the plants have no barbed hairs or glochids. This tribe is the smallest of the three groups, but is interesting because of its large leaves which are found on none of our native species, and its resemblance to an ordinary tree, shrub or vine according to the habit of growth of the individual species. There are a few other tropical cacti belonging to the following tribe that also have leaves, but those plants lack one or more of the other characteristics which distinguish the tribe of Pereskiece. Members of this group do not usually thrive in colder climates even under glass, but, although not generally cultivated, it affords the amateur much satisfaction to be able to recognize them when encountered.
The tribe, the Opuntiea, contains some of our most common and best known cacti. None of our native cacti belonging to this group have leaves which persist throughout the season, although some of them have tiny awl-shaped leaves on the new growth. These leaves drop off within a few weeks, and, since they are so small, few casual observers know that they ever existed. One small group of tropical plants (Pereskiopsis) in this tribe have leaves somewhat like the previous tribe, but the leaves are smaller and more fleshy. The plants belonging to the Opuntiea, except in the small group, Maihuenia, all have the barbed hairs, or glochids, which are absent in the first tribe, and their flowers are not on a stalk.
Our common prickly pear is a member of this tribe. The large, flat slabs of these plants, so commonly considered leaves, are only joints of a greatly modified stem which do all of the work of regular leaves. When the true leaves drop off the new growth, there is left, where each was attached, a little cushion from which the spines grow and sometimes the flowers. In this tribe, the cushions have a felt-like wool and the barbed hairs which we have been calling glochids. Each cluster of spines on the mature growth represents a leaf-scar.
The flattened stem is so common in the group that one may easily forget that this is not one of the distinguishing characters of the tribe. Some members have stems that are more or less cylindrical and are described by the term, terete.
It may be well for the sake of convenience to restate in more concise form the characteristics of the tribe :
1. Leaves (except in Pereskiopsis) very small, cylindrical or awl-shaped, remaining on the plant but a short time.
2. Flowers without stalks, directly attached to the stem of the plant.
3. Flowers without definite tube.
4. Glochids always present, except in Maihuenia.
The third tribe, the Cereeae, contains all other cacti. The characters used to distinguish them may be given as follows:
1. Usually no leaves on the vegetative parts except the first two seed-leaves on the seedlings.
2. No glochids are present.
3. Flowers have definite tubes, except in Rhipsalis.
Most of the forms of cacti so dear to the collector's heart belong to this group. Many of them are weird, fantastic, grotesque. Some of them have such beauty of structure and glorious bloom that no other plants can rival them.
The tribes are divided into still smaller groups, each one known as a genus (plural, genera) . The members of the genus re-semble each other much more closely than do the members of the tribe. Although they have all the characters distinctive of the family and of the tribe, each one has additional characteristics common to all other members of the genus. There are one hundred and twenty-five genera of cacti which are generally recognized by botanists.
The genus is composed of groups of individuals designated as species. To define satisfactorily the term species in a technical way is a very difficult matter and would serve no useful purpose in this place. We should, however, have a practical under-standing of the term because all literature, all conversation, and, one may be justified in saying, all interest in cacti is centered in the species. A cactus is merely a plant claiming superficial interest until the species to which it belongs is known. Immediately, it becomes more than a cactus—it becomes an individual, it assumes a personality, it becomes a friend. Its identification opens a field rich in knowledge and interest. The plant has a native home. It has developed in certain ways to meet the adverse conditions of that home. There are close relatives to be studied and their methods of coping with life's problems compared with those of the little friend at hand. All of this helps the owner to care for his plants with that intelligence, understanding and sympathy so necessary for their successful culture.
The species is a group of individuals that resemble each other in all their constant characters. Seedlings from one plant resemble not only the parent but the other members of the species as well. Under natural conditions, members of one species seldom, if ever, cross fertilize with members of another species.
Of course, no two plants in a species are exactly alike. Each one has its own little individual differences, but those differences are not constant—they are not handed down from one generation to the next. Occasionally a group of individuals within the species has one or more trifling characters in common which seem to be more or less persistent but are not sufficiently stable to warrant consideration as a species. These groups are known as "varieties."
There is still another interesting condition which is sometimes observed. Members of a species in one locality may differ considerably from members of the same species growing in another section of the country, such differences being entirely due to differences in climatic and soil conditions. Young plants transferred from one locality to the other, soon assume the appearance of plants belonging to the same species already growing in the new locality. These plants are called "forms."
There are approximately fifteen hundred species of cacti now known, but only a small number of these are to be found in the United States either in their native habitat or in the gardens of cactus devotees. In "An Annotated List of Plants Cultivated in Santa Barbara," published by Garden Tours Committee, Santa Barbara, 1930, only three hundred and eighty-seven species of cacti are listed.
Scientific names should not be considered a stumbling-block by the amateur. But how often has he felt his enthusiasm oozing away in the face of such a name as Echinocerus pentalophus, and was then saved from being completely routed by discovering that it is only the little "lady finger" cactus. Common names are much easier to remember, and they seem friendlier, but they are too indefinite to be entirely satisfactory. A person may learn the common name of a species and then find that a friend in another section of the country is calling quite a different species by that same name. A foreign correspondent would not know what species were being discussed if only the common names were used, but the scientific names are known and are the same for each species in every nation and language in the world.
Scientific names are not composed of letters jumbled together in tongue-twisting combinations for the purpose of confounding the uninitiated. They are composed of words or combinations of root words which have a very significant meaning. They are of Greek or Latin origin, and usually the various root words are derived from one of three sources. Sometimes part of the scientific name is the Latinized name of the man who discovered the plant in the field or has been an outstanding contributor to the knowledge of the group of plants. Echinocerus lloydii was first discovered and collected by T. E. Lloyd and was named by Dr. Rose in honor of him,
The names of a few species indicate the locality in which the species is found. Homalocephala texensis is, of course, named for the State of Texas where it is widely distributed.
Most of the scientific names, however, are based upon some outstanding characteristic of the genus and species. Any fairly good dictionary will tell you that "echino" comes from the Greek word echinos meaning hedgehog. The generic name, Echinocactus, means simply "hedgehog cactus." The word "cactus" itself, so this same common dictionary tells you, comes from the Greek word kakios, meaning a prickly plant. It is not necessary to be a Latin or Greek student in order to analyze these names. A good dictionary, a little patience, and the beginner is soon launched on a most interesting and intriguing pastime that will add un-told pleasure to his collection of cacti.
The scientific name of a plant is composed of at least two words. The first word al-ways begins with a capital letter and is the name of the genus. When the generic name is repeated a number of times, it may be indicated by using the first letter of the name as an abbreviation. The second word of the name is the name of the particular species. If there is a variety to be indicated, the name of the variety follows the name of the species. Usually the name or an abbreviation of the name of the author of the species, as the man who first described the species is called, follows the name of the species or variety.
This discussion has been too brief to be truly satisfying, but it is hoped that even those only casually interested in this fascinating group of plants may have a new vision of the delightful pleasure which a little thought and a little study in this field will yield them.