The Basic Botany of Bulbs

     We tend to think of vegetables as things to eat. For this reason I prefer the classification Plant Kingdom, as is used in Great Britain, rather than Vegetable Kingdom. But where in the order of things do plants fit? The Roman writer Pliny devised a classification, not scientifically accepted today, that I am sure is used by gardeners the world over, the majority of them knowing nothing about Pliny, and possibly caring even less! Pliny's criteria are size and form, and he divides the plant kingdom into trees, shrubs and herbs -a very sensible arrange ment. In the Middle Ages another classification, also quite sensible, divided plants into medicinal, edible and poisonous varieties. However, this tells us nothing about the actual plant; a tree, for example, can be considered all three. Still, this was, when combined with the earlier classifica tion, a useful tool. We could have a medicinal tree, an edible herb and a poisonous shrub. Man was getting there.

     Looking closely at plants, the great Swedish botanist Carolus Linnaeus devised a classification based on the number of stamens in the flowers of plants. Although this classification was discarded, Linnaeus introduced a system of naming plants still used today. The scientific, or botanical, name of a plant is the same the world over, and each plant has only one correct name. Our Easter lily is Lilium longiflorum to someone from China, England or France. Locally used common names vary widely, but scientific names are recognized by all. Linnaeus devised the scientific, two-name method of identification, the genus (plural, genera) being the first, followed by the species name, the second.

     The plant kingdom is divided into two subkingdoms: Thallophyta (plants that do not form embryos), such as bacteria, slime molds, various algae and true fungi, and Embryophyta (plants that form embryos), the subkingdom into which bulbs fall. Embryophyta is broken into Bryophyta (mosses and liverworts), obviously not bulbs-and Tracheophyta, plants with vascular systems. Tracheophyta includes the subphyllum Pteropsida, which is divided into three classes: Angiospermae, the true flowering plants; Filicineae, the ferns; and Gymnospermae, the conebearing plants and their relatives, such as the conifers.

     With bulbs as our topic, we are concerned with only one of these classes, the Angiospermae. But there are many flowering plants, and this class is divided into two subclasses: Dicotyledoneae and Monocotyledoneae. In everyday speech these plants are referred to as "monocots" and "dicots." Monocots produce one leaflike structure after the seed germinates; dicots, two.

     After germination, as plants develop, they produce true leaves. Monocots have leaves that are generally alternate, with parallel veins and simple form. The flowers are constructed of four alternating whorls of parts-sepals, petals, stamens and carpels-with each part being trimerous (in threes or multiples of three). This is worth knowing, as it helps in the identification of flowers.

     Dicots have leaves veined in a netlike pattern, and usually the leaves are narrow at the base and have a petiole. In dicots the parts of the flowers are usually in multiples of five and are called pentamerous (5-merous), or in fours and called tetramerous (4-merous), and they have a distinct calyx and corolla. (Some of these terms might be foreign to the reader. Turn to page 6 for a discussion of flower parts and their functions.)

     These classes and subclasses are again divided into orders, each order containing one or more families. If this sounds complicated, don't worry; now we are getting to the more relevant information on the orderly classification of our bulbous plants.


     It is perhaps easier to understand what comprises an order if we examine one in particular. Lilies are my favorite flowers, so let's look at the order in which these lovely plants belong, together with the iris and the amaryllis. Similarities join these families -Liliaceae, Iridaceae and Amaryllidaceae-in the broadest way. This trio of families make up the order Liliales.

     All these families have flowers made up of three petals and three sepals; ovaries that are in three parts; and six stamens in two rows of three each (Iridaceae have one row of three). It is certain an iris is different from a lily, yet if you picture the single flower of a gladiolus, a lily or an amaryllis, you can begin to appreciate that they have quite a lot in common.


     The ovary is located in the center of the flower. The petals and sepals are attached to the flower below the ovary in the case of the lilies; because the ovary is above that attachment point, it is called "superior." Tulips and lilies are in Liliaceae. In Amaryllidaceae the flowers have the same parts as they do in Liliaceae, but the ovary is located below the point where the petals and sepals are attached, and thus it has an "inferior" ovary. The amaryllis and the daffodil have inferior ovaries, and are classified in Amaryllidaceae.

     When we take a look at the iris, gladiolus and crocus, we find that, like the plants in Amaryllidaceae, the flowers have inferior ovaries but only three stamens. There is another significant difference in these members of the Iridaceae; the outside petals are broad and recurved (they curl back), and the inner ones are narrow and erect. At first glance there are many similarities among these three families (remember, they are classified in the same order: Liliales). Upon closer examination, however, differences are evident, and so they merit being classified into three different families.

     The juxtaposition of petals and sepals, the number and placement of several parts of the flowers, is similar, yet the differences are sufficient to merit three different families. It's rather exciting to realize that if you do not know the name of a flower but note that it has three sepals, three petals, an inferior ovary and three stamens, you know it belongs to Iridaceae. You can then check the genera (singular form: genus) in this family, and so arrive at the identification of the plant.


     But we have now introduced another word, genera. Every family has one or more genera. All daffodils and narcissus, for example, belong to the genus Narcissus. The flowers of plants that are structurally the same are classified in the same genus. While the tulip seems, in number and placement of flower parts, the same as the true lily, there is an obvious difference, one that can be seen just by looking at the plants; apart from the flowers, the foliage is different. The tulip has no foliage on the stem, but the lily does. The lily has several flowers on each stem, but the tulip seldom more than one, and the form of the flower head is different. Thus, while related (both in the order Liliales and in the family Liliacea), the tulip and the lily are different. The tulip is placed in the genus Tulipa, and the lily, in Lilium. Now we have an understanding of the meaning of the word genus. This brings us to the next step of classification.


     There is a difference between an Easter lily and a tiger lily. The plants are classified in different species. The Easter lily is Lilium longiflorum, the tiger lily is Lilium lancifolium. How is the species name determined? It can describe the flower"grandiflorum" means "large flower," "rubrum" means "red," "album" means "white." It can honor the person who discovered it, as in the case of Lilium davidii, named after Armand David, who discovered it in western China in 1904. A specific name can provide information about the geographical area where the plant grows, as in the case of Lilium canadence, a lily that grows wild in eastern Canada. Frequently a plant of one species may look very much like another classified in the same species, but yet is not exactly the same. A slight but consistent difference is enough to warrant separating two very similar plants, though they share the same species. Flowers may be fewer but larger, leaves wider, the plant a little shorter. Such differences are not sufficient to merit the variant being given full species rank, but the difference has to be acknowledged. In such cases the plant in question is described by the original species name, and is given a "subspecies" name after that.


     A good example is the case of Lilium canadense. It was noted that the form growing east of the Appalachian Mountain Range has broader leaves that are not as tapered as others. For this reason, these plants are known as Lilium canadense subsp. editorum. The word "subsp."-short for subspecies-is not italicized, the other names-genus, species and subspecies-are.

Elegant, free flowering, and full of grace, Lilium canadense is a must if you have a woodland setting, where it should be left undisturbed for years.

     While such a physical difference is given subspecific rank, it would not always be merited just by flower color. The natural reproduction of the species in the wild, by means of seed, can produce seedlings of a different color. If this color (color is used as an example-height and foliage form might ht be other examples) is consistently found might consistently the same, then that variant is known as a variety of the species. If the usual color of the flowers of one species was red, but consistently a white-flowered plant was found, then the words "var.," album" would be added to the name. The album would be in italics, but not "var.," which is the accepted shortening of the word variety.


     Many people refer to a plant as a "variety" of this or that. `Peace' is called a "variety" of rose, `Big Boy', a "variety" of tomato. But in both these cases the variety has been man made, and these plants are the result of hybridization. Obviously the same is true of the "varieties" of tulips, gladiolus, dahlias and many other popular bulbs. These are correctly known as cultivars, meaning they were created by humans.

     The correct way of writing a cultivar name is within single quotes; it is not italicized. Thus, we have Tulipa 'Clara Butt' and Lilium `Enchantment'. The cultivar name is selected by the producer of the new plant, and once registered, the name cannot be used for another introduction in the same genus; it can be used in a different genus. Thus you may well find `Peace' used for a rose, a lily and a gladiolus as they are all different genera.

Cloned and Strains

     In the case of the lily `Enchantment', all existing `Enchantment' lilies were derived from a single, original bulb by vegetative propagation. This means part(s) of the original bulb were removed and grown on. The resulting plant is known as a clone. Purchase a `Red Emperor' tulip and you expect a tulip identical to that you purchased under that name in previous years. `Golden Delicious' apples are the same everywhere, because they are all clones.

     Sometimes plants-certain lilies, for example-are sold as "strain." `Golden Splendor Strain' is a lily strain. Often when a strain becomes well established, the word "strain" is dropped, so you might see the bulbs sold as `Golden Splendor'. A little variation may be found among plants of the same strain, but the differences will be slight and all would be recognizable as `Golden Splendor'.

     Strains are raised from seed. Selected parent clones are crossed, and the offspring are the strain. As years go by, strains are often improved. Hybridizers constantly upgrade the quality. Deeper color, stronger stems, increased size and number of flowers-such improvements are made by changing the parent clones used to produce the seed from which 'Golden Splendor' plants, for example, are raised. The cost of introducing a new strain into the market is high. Once a strain has been established and has earned a reputation, it pays the grower to continue to market the strain. Over time that strain may be improved in a dramatic way, yet because of name recognition, the name is continued. It is not critical for the home gardener to know whether a plant is a strain or a clone. It is essential for the nurseryman, who might be forcing the bulbs, to know. Why? Clones, identical in every way, will respond in a given way when forced. A strain, made up of individuals, will show variations, perhaps some coming into bloom earlier, or later, or being shorter or taller. Such variations, even slight ones, cause problems when schedules are prepared; greenhouse space is valuable, and such variations can be quite costly.

     You will find reference to hybrids in many books and catalogs. We are all hybrids ourselves! We are the result of the crossing of our fathers and our mothers. So it is with plants. New plants derived by crossing two plants are hybrids. When species from two genera are crossed, which happens rarely, we call the result an intergeneric hybrid. One such intergeneric hybrid in the world of bulbs is X Crinodonna. This was a result of crossing a Crinum with Amaryllis, belladonna. The hybrid has a bit of both parents' names, and is preceded by a multiplication sign.


While visiting a breeder of Alstroemeria, wonderful plants that are great cut flowers, I came across this specimen, which has good color and great vigor.
     Horticultural classifications are needed for a number of purposes. They allow accurate comparison and competition with other plants of the same ilk. You have probably noticed that some dahlias have flowers the size of dinner plates. These large flowers are called decorative. Other flowers are single, others still are shaped in little balls, or are small, medium or large, or ruffled. We classify these differences in order to describe the plants accurately. Obviously to be correct in competition and in our gardens, we want to be able to select the exact type of flowers we want. Knowing that this cultivar (or strain) is of a certain class enables us to obtain exactly what we want. Similar types are classified together.

Listed in catalogs but not as popular as it should be, Fritillaria persica is an easy-to-grow species with flowers and foliage that form a pleasing combination.
     Not all genera have been refined to this degree, just the larger ones with many different types and forms. Daffodils (the Narcissus), tulips, lilies, dahlias, crocus, gladiolus and iris have horticultural classifications. These classifications are compiled by students of the various genera. They are logical and, unlike scientific classifications, horticultural classes are based on criteria plainly visible to the naked eye; understanding them doesn't require great botanical knowledge. Is it really necessary to know much about genera, species, families, subspecies and clones in order to garden? Of course not. If a gardener is going to have a measure of success with plants, he or she must have a love of beauty and of plants themselves. A gardener must be orderly, thoughtful, observant and imaginative. A gardener must have the ability to look into the future and picture the garden that is being created. A given garden may lack form and color, but invariably one finds a plant growing there to perfection, and this excuses many a fault. But achieving a good garden, having plants complement each other in an attractive border, where each plant is in just the right place, does require knowledge. Knowing the relationship of one plant to another, knowing the names, where they come from and the conditions they enjoy in the wild, may not be essential to creating a garden. But it certainly is not a disadvantage to have such knowledge, and the more you know about plants in general, and individual plants in particular, the more enjoyment you will have from gardening. The scientific aspect of horticulture is directed as much toward the improvement of the gardener as of the garden itself. Perhaps one is the reflection of the other. Try to learn and understand as much as you can, but don't worry too much over it. The plants know how to grow -we do not need to teach them!


     There is an obvious need to describe the form and shape of flowers, their colors, petals and sepals. It is a good idea to be acquainted with the various parts of a flower, and their functions, too. When a description is given in a catalog, you want to be able to envision the flower, and then plan for the best location for the plant, and place complementary plants around it.

Iris ochroleuca is a lovely species that remains in flower for a long time, a quality passed to its offspring the Spuria Iris (the other parent being Iris spuria). Bold plantings add much interest to a garden.
     A flower is made up of several parts. Those essential for reproduction are: the stamens, the male part of the flower that produces pollen; and the carpet, the female part that in the majority of cases is made up of the stigma, style and ovary. The seed is produced in the ovary, and it is the purpose of the flower to produce seed so the plants can reproduce themselves in seasons to come.

     Essentially, it is the perianth segments that one commonly thinks of as a flower, and generally there are outer and inner segments. The outer whorl of segments is called the calyx, a collective name for the sepals. These protect the inner parts and though they can be green, in most bulbous plants they are another color. When joined together they form a tube, as is the case with crocus flowers. Inside the sepals are found the petals, generally brightly colored, and though the sepals and petals may be of the same color, they are not always so. The collective name for the petals is the corolla, and when the petals join to form a tube, as in the daffodil, it is from the end of the tube that the corona extends. It is this corona that forms the mouth of the trumpet in many of the large-trumpet daffodils, and it is an extension of the tube.

     Often a trumpet is formed by the sepals and the petals, without it being possible to tell one from the other. This type of trumpet is said to be made up of tepals; trumpet lilies are a good example. It is also impossible to differentiate between sepals and petals in the case of tulips, and for this reason a tulip flower is said to be made up of tepals.

     Inside the perianth segments are found the stamens. At the top of the stamens are the anthers, which carry the pollen grains. Usually (but not always) yellow, the grains are the equivalent of human sperm. Anthers are supported by filaments or stalks, and sometimes these emerge from the perianth tube, as can be seen if you cut open a daffodil flower. In those families regarded as relatively primitive, such as Ranunculaceae, there are many stamens; in the advanced families, such as Liliaceae, there are fewer. Stamens are placed so that there is a good chance of pollination occuring, the transfer of the male gametes (pollen) to the female part of the flower so that seed can develop.

     The ovary is found in the center of the flower. Above the ovary is a slender tube, the style, terminating in a structure called the stigma. The stigma catches the pollen in various ways. Pollen carried by wind can be caught by a branched stigma or one with feathery appendages. Some stigmas exude a sticky substance that traps the pollen traveling on the hairy legs and bodies of such insects as bees.

     The pollen grain germinates on the stigma and forms a tube down through the style. The male gamete travels down the tube, and when the tube comes into contact with the female gamete, the male and female unite, and a seed is formed. This may be a simplistic way to describe what takes place, but it is not inaccurate. Many regard the fluid excreted from the stigma as food for the germinating pollen grain(s), as well as being a substance to trap the pollen. The purpose of the color and fragrance of flowers is to attract insects. At the base of the petals there may be glands that excrete a sweet substance that is also attractive to them. This substance is nectar, made into honey by bees. It is from these nectaries that scents of flowers are also excreted. Some nectaries are visible to the naked eye, as is the case with lilies, others are visible only with magnification.

    ARACEAE FLOWER                               DAFFODIL                               BEARDED IRIS
     These remarks offer insight into the purpose and composition of a flower. There are many adaptations, and the illustrations on pages 8-9 will help in understanding the physiology of various bulbous plants.

On Arranging Lilies

Often when lilies are used in an arrangement, the stamens will be cut off and discarded. This is to prevent the pollen from staining the clothes of the arranger or of someone admiring the flowers. To me this decreases the attractiveness of the flowers, but it is understandable. The stigmas of lilies often produce so much fluid that it drips, and as it is extremely sticky, this can be a disadvantage. Precautions taken to avoid problems include clipping off the stigma. Again, in my opinion, this disfigures the flower. If pollen happens to stain a garment, allow it to dry, then simply brush it off. If stigmatic fluid drips onto furniture, a little warm water on a clean cloth will remove it easily. If pollen stains petals, it can be removed easily with a ball of cotton dipped in milk.


     Not all bulbs produce flowers with recognizable petals and sepals. An example is Haemanthus, where the color is due to many perianth segments that form a tube from which stamens protrude; there are six stamens per "flower," and many flowers in a flower head. Thus the common name of paint brush is often given to these flowers. Another example is the calla lily, where the female and male flowers are arranged on a spadix that looks like a long cylinder inside the colorful spathe, and which surrounds the cylindrical column of flowers. Technically this spadix is a fleshy axis on which the sessile (stalkless) male and female flowers are arranged. This arrangement is typical of the family Araceae, the Arum family, and it is the spathe that is colored and attractive. In the case of these flowers, the fleshy axis secretes a sticky substance that attracts insects and thus encourages pollination.

                    LILY FLOWER                    LILY STEM                     CROCUS
     The composition of flowers is a fascinating subject. They are complex and deserving of greater discussion, but that is not the purpose of this book. I do feel that the information in this chapter is basic knowledge essential for all gardeners worthy of the name to understand. Flowers are indeed wonderfully made. It is hoped that the reader will take a minute or two to enjoy exploring the composition and texture of flowers.

New hybrids are the result of years of work by hybridizers. We thank Klehm Nursery for this lovely Siberian iris `Heliotrope Bouquet'. (Photo courtesy of Roy Mehra)