chapter 19 Plant Propagation UW-EXTENSION MASTER GARDENER MANUAL: FOUNDATIONS IN HORTICULTURE Introduction Plant breeding any gardeners plant seed The terms “plant breeding” and In a nutshell… in the ground and watch “genetic engineering” are often it grow. Others browse confused. Both are methods of • Propagating plants is a fun way the garden center for developing new plants with desirable to create new plants. Mvarieties of plants with little thought characteristics. Genetic engineering is • You have to think about plants to where they came from. Some divide essentially a type of breeding. in a diferent way if you plan on plants in their gardens to improve Plant breeding has been practiced saving seeds. vigor or to share with a neighbor. In for thousands of years. It involves • We’re talking plant sex: You studying plant propagation you will pollinating the fowers of a chosen need to understand how learn how to afect a plant’s growth by plant with pollen from another plants reproduce to be able to manipulating environmental growing chosen plant, both with desirable efectively propagate them. conditions, resulting in more plants. characteristics. The seeds produced • For issues not covered in this In gardening, plant propagation refers are then planted and the resulting chapter, contact your county to the many ways of starting new plants are evaluated for their quality. Extension ofce: plants. These various processes of Promising plants are “selected” for counties.uwex.edu multiplying or perpetuating a plant their desirable characteristics or to be species may be by natural or artifcial used for further breeding. With plant means. This chapter introduces breeding, the same pollination could concepts and techniques for growing theoretically occur naturally; human new plants from seed and by asexual involvement directs which two plants methods. are combined. Genetic engineering is a relatively new Learning technology that involves manually inserting the DNA from one organism objectives into the cells of another. In some Understand the biology involved in cases, the gene inserted into a plant 1 plant propagation. is not from another plant, but from Know the conditions for starting a diferent organism altogether. seeds. For example, Bacillus thuringiensis 2 is a bacterium whose DNA is often Demonstrate techniques for inserted into plants to provide pest 3asexual propagation. control. Genetic engineering involves a recombination of genes that could not occur in nature without human involvement.

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Patents, trademarks, and trade Propagation basics names Plants can be propagated in two main ways: Plants developed through traditional breeding sexually and asexually. Sexual propagation or genetic engineering have a unique, desirable is the recombination of plant genetic material characteristic that can be patented by the to form a genetically unique individual. This government. A patent gives the recipient generally involves the foral parts of a plant, the right to exclude others from asexually pollination that results in the formation of seeds, reproducing, selling, or using the plant for a set and starting plants from seed. time, usually 20 years. Patent holders can sell Asexual propagation produces new plants licenses to producers who are authorized to that are genetically identical to the parent plant propagate the plant, and it is illegal for those by taking a vegetative part of the parent plant without a license to reproduce and sell the plant. (stems, roots, leaves, or other non-reproductive Of the hundreds of thousands of plants available, plant parts) and causing it to regenerate into a only a small number of them are patented. For new plant. a plant to be patented, it must be distinctly diferent from existing cultivars. Patents are not Sexual propagation: awarded for plants found in the wild. Trademarks are words, acronyms, phrases, logos, from seeds or symbols that identify the source or origin of Propagation by seed is a common method of a plant or type of plants. A trademark does not producing new plants. Sexual propagation may be give exclusive rights to the plant as a patent does, cheaper and quicker than other methods, and it is but it prevents others from using the trademark. a way to obtain new cultivars and hybrid vigor. Trade names identify a company name, but do Seed propagation results in a lot of genetic not specifcally identify a plant or product. variability, so ofspring may not have the exact characteristics of the parent plant. Seedling variation is quite high in some plants; many ornamental plants do not come “true” from seed. Other plants are more true to type. Many All-America selections vegetables and annual fowers are easily grown from seed. Some perennials can also be grown All-America Selections (AAS) is a non-proft from seed, but may not fower the frst season. organization that tests and introduces signifcantly improved new fowers, Pollination and fertilization bedding plants, and vegetables grown Pollination and fertilization are processes that from seed. AAS tests are conducted at trial result in the formation of new seeds. grounds throughout North America with • Pollination is transfer of pollen to the female ofcial AAS judges supervising the trial and fower parts by wind or pollinators, such as evaluating each entry. AAS Winners have bees or other insects. been tested for home garden performance • Fertilization is the union of the male and and are quite reliable because of these female reproductive material. unbiased, independent tests. AAS Display Gardens in the U.S. and Canada are open • The stamen is the male portion of the fower to the public to provide gardeners with that produces the pollen. opportunities to view the most recent AAS • The dust-like pollen is contained in the Winners. anthers, the sacs at the end of the flament. • The typical female pistil consists of an enlarged ovary (containing the egg) at the base, a columnar style and the stigma, the organ that receives the pollen on the end. 332 PLANT PROPAGATION chapter 19 When pollen grains land or are placed on the The embryo is a new plant resulting from the stigma, they germinate to form a pollen tube that union of pollen and egg during fertilization. grows down the style to the ovary, allowing the Cotyledons, or seed leaves, are attached to the male reproductive material to move to the egg embryo. Monocotyledons (monocots), such (fgure 1). Once the male reproductive material as grasses, have one cotyledon; dicotyledons fertilizes the egg, seeds can be produced. To (dicots), such as beans, have two cotyledons. understand these processes, it is important to A mature seed contains enough stored food (or know the parts and functions of a fower (see energy source) for seed germination and early chapter 1, Botany). seedling growth. The cotyledons of dicots usually FIGURE 1. The parts and functions of a fower contain this food reserve, while some seeds like monocots have a mass of food reserve called an stamen pistil endosperm. Seed coverings are the seed coat and parts of anther stigma the fruit or seed pod. These structures protect the embryo and food reserve inside the seed and flament style sometimes prevent germination until conditions are suitable. ovary Selective pollination petal Four seed types can be produced by selectively pollinating plants with specifc parents: inbred lines, F1 hybrids, F2 hybrids, and seed mixtures. Inbred lines Inbred lines are created when plants from a single sepal parent line are self-pollinated or interpollinated so they become nearly identical after several Anatomy of a seed generations. These fowers or vegetables are A seed is usually made up of three basic parts often easier and faster to breed and produce. (fgure 2): Common self-pollinated, non-hybrid, and • The embryo purebred annuals and vegetables are suitable candidates for saving seed. • A food supply • Some vegetable seeds that can be easily • The outer protective covering saved include lettuce, beans, peas, herbs, and FIGURE 2. Anatomy of a seed heirloom tomatoes. • Annual fower seeds that can often be plumula successfully saved include cleome, salvia, and nicotiana. hypocotyl embryo

radical

micropyle

cotyledon

seed coat

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F1 hybrids Seed saving F1 hybrids are created by crossing two inbred Seed left over in a package after planting can be parent plants—often that difer in several saved for next year’s garden, usually with little important traits—resulting in uniform, often very loss in germination, if stored properly (see “seed prolifc plants. Control of the cross-pollination of storage”). these plants is critical for hybrid seed production. You may also choose to save seed from plants These crosses are made to develop qualities like you grow in your garden from one year to the good vigor, heavy yields, uniformity, disease next. Saved seed may not produce plants that are resistance, and other desirable traits. Hybrids the same as the parent plant. Cross-pollination are often more vigorous than either parent, in some crops may result in altered genetic but cannot breed true. Seeds collected from F1 characteristics, so new plants grown from these hybrids will not produce plants identical to those seeds might have any combination of new from which they were collected. characteristics, such as fruit size, blossom color, F2 hybrids shape, or favor. Some vegetables that are self- pollinated and therefore are good seed-saving F2 hybrids are the result of self-pollination or bets include beans, eggplant, peas, and tomato. indiscriminate pollination of F1 hybrids. These plants are more variable than the original hybrid Seed storage but may maintain some of the characteristics of It is important to store seeds properly to maintain their parents. Plants grown from seed saved from their viability. Seed is a living product that, once F2 hybrids can be variable and unpredictable. harvested, is constantly in decline. The storage Seed mixtures life of seed depends on both environmental conditions and the plant species. Most fower and Seed mixtures contain seeds collected from vegetable seeds will keep for one year without plants—generally fowers—that vary only in a special protection, and many will remain viable single trait, such as color. Field grown mixtures for up to 5 years if stored properly (table 1). The come from plants of diferent colors growing best conditions for seed storage are just the together, which can result in slightly variable and opposite of those required for germination— unpredictable color mixtures. Formula mixtures cool, dark, and dry. blend seed in predetermined proportions from plants of diferent colors that were grown In general, the drier the seeds, the longer they separately to produce a constant and predictable will last. A relative humidity of 30% is ideal. The balance of colors. highly variable environment in the average home allows far too much (or too little) moisture Obtaining seeds exchange for long-term storage in paper Seed selection envelopes, cloth bags, or cardboard boxes. Place Purchase good quality seed from reputable seed seeds in an airtight container such as tight- companies that produce seed with controlled sealing glass jars or resealable plastic bags. To genetics and store seed properly. help reduce moisture in the container, you can

TABLE 1. Storage life of fower and vegetable seeds

LONG-LIVED SEEDS MEDIUM-LIVED SEEDS SHORT-LIVED SEEDS (5 OR MORE YEARS) (UP TO 5 YEARS) (1 TO 2 YEARS) beets, broccoli, Brussels sprouts, basil, beans, calendula, carrot, alyssum, aster, blanketfower, cabbage, caulifower, cilantro, celery, chard, dianthus, dill, coleus, corn, cosmos, delphinium, cucumber, lavender, lettuce, eggplant, forget-me-not, lupine, leek, onion, pansy, parsnip, phlox, melons, mustard greens, oregano, marigold, nasturtium, parsley, spinach, strawfower peppers, radish, sunfower, tomato, peas, pumpkin, sage, snapdragon, turnip squash, sweet pea, thyme, zinnia

334 PLANT PROPAGATION chapter 19 include a desiccant such as calcium chloride, silica • Each type of plant has an optimal sprouting gel, or powdered milk—any of which will absorb temperature. Although most seeds will moisture from the seeds—but do not allow the germinate at lower temperatures, it may desiccant to touch the seed. take 10 times as long. Slower than optimal Store seeds in a cool place with temperatures germination also increases the chance for between 35 and 50˚F. Cool temperatures slow disease. Warmth usually improves germination, seed respiration, prolonging seed life. Constant with most plants doing well at 60 to 75˚F. Most cool temperature and humidity will break the seeds have a fairly wide temperature range, dormancy of certain seeds and slows the gradual but some are more limited. The temperature loss of viability in seeds that are not dormant. A range is usually listed on the seed packet or cool corner of the basement—away from heat in the catalog. For most vegetables, raise the sources such as furnaces, water heaters, or warm- temperature of the medium a little above air ducting—such as a root cellar or vegetable that of the average house for the best results. storage area is adequate for storing most seeds. A Bottom heat is preferred and can be supplied refrigerator will also provide suitable conditions by an electric heating mat specially made to for seed storage. place under fats of seedlings, with heating cables, or just by placing the pots in a warmer Absolute darkness is the best for seed storage. location in the house, such as on top of the Exposure to direct sunlight or bright, artifcial refrigerator or near a radiator (but be sure the light—one of the conditions that stimulates spot isn’t too warm). Once the seedlings have germination—can reduce seed viability and sprouted, a lower temperature is usually best vigor. for seedling growth. Germination Planting seeds when the water, oxygen, light, Germination is the active growth of the embryo and temperature conditions are optimal, whether in the seed that results in breaking of the outdoors for direct seeding or indoors for seed coat and emergence of a young plant. transplants, will increase germination rates and Germination is afected by water (moisture), speed. oxygen, light (or dark), and warmth. Seed dormancy • Water is essential to inducing germination. When seeds ripen, they are quiescent—in an Water penetrates the seed coat and causes the inactive stage that enables them to survive for a endosperm to swell, which in turn causes the long time. When given the proper environmental seed coat to split open as growth begins. Keep conditions seeds germinate readily. But some the growing medium moist but not wet. If the plant species may not be able to germinate medium is allowed to dry out, the sprouting even when planted in favorable environmental embryo may die; excessive moisture, however, conditions. Viable seeds that do not germinate can lead to disease and rotting. are in dormancy, a lack of growth due to an • The embryo needs oxygen to begin growing. external or internal cause. Dormancy can be This is one reason to use a light, well-aerated regulated by the environment or by some growing medium to start seeds. inhibitory factor of the seed itself, and may be • Light can stimulate or inhibit a seed’s caused by several diferent mechanisms. Dormant germination. This is why some seeds need to seeds must undergo certain changes before be sown on the surface of the growing medium germination can occur. Depending on the type and some below the surface. Check the seed of dormancy, diferent techniques can be used to packet or catalog for light requirements. break dormancy. An impermeable seed coat is one major mechanism of dormancy, in which the seed covering physically restricts water uptake or is too hard to allow embryo expansion. The embryo 335 UW-Extension Master Gardener Manual: Foundations in Horticulture

inside is generally quiescent, so if the seed coat Internal dormancy is a general term can be opened, the seed will grow. In nature encompassing a number of physiological certain environmental agents soften seed coats: conditions that delay germination. Not all of • The acid in digestive tracts of animals that these conditions are fully understood, but may be ingest the seeds. regulated by the embryo itself and involve plant hormone dynamics. These seeds—including • Microorganisms in warm, moist environments. those of many trees and shrubs and certain • Forest fres. perennials—must be exposed to moisture and • Weathering by exposure to freezing and cold temperatures for a certain period of time. thawing. The most common method for breaking internal The length of time needed to soften the seed dormancy is cold stratifcation, or moist chilling. coat depends on the plant species, and may be This simulates the cold winter conditions that the several years or more. seeds would encounter in nature. The most common technique to overcome seed • Mix the seeds with an equal volume of a coat dormancy is scarifcation, physically altering moistened medium (such as vermiculite or peat the seed coat to allow moisture penetration. Two moss) in a closed container and store them in a methods of scarifcation commonly used by the refrigerator (approximately 40˚F). home gardener are mechanical and hot water. • Check the containers periodically to see that • Mechanical scarifcation can be done using a the medium is moist but not wet and to see if metal fle, a pin, or a knife to make an opening they have started to germinate. The length of in the seed coat or by rubbing the seeds time it takes to break dormancy is generally between two pieces of sandpaper. Larger seeds greater than 8 weeks, but varies by species. may even be gently cracked with a hammer. • Don’t remove the seeds too early, or a Take care not to injure the embryo. Sweet pea secondary dormancy that is more difcult to seeds beneft from scarifcation before planting. break than the original may be induced. Plant seeds soon after scarifcation, as they are • Warm stratifcation is similar except more susceptible to microbial infection. temperatures are maintained at 68 to 86˚F, • For small to medium-sized seeds hot water depending on the species. treatment is more practical than mechanical • Sow the seeds promptly after stratifcation scarifcation. Drop seeds into about six times before they dry out. their volume of 180 to 200˚F water and leave the seeds to cool and soak in the water for 12 Double dormancy is a combination of seed to 24 hours. Cacti, morning glory, and many coat and internal dormancy. To overcome this, prairie perennial dicots can beneft by such the seeds generally must be scarifed frst and treatments. then stratifed for the appropriate length of time. Other species may have two or more distinct Chemical inhibitors in the outer coverings of internal dormancy factors, requiring a sequence many fruits and seeds may cause dormancy, of diferent temperatures to initiate germination. particularly in seeds with feshy fruits, hulls, or This is often a warm period to stimulate primary capsules. This kind of dormancy often disappears root growth, then a cold period to break shoot with dry storage. In nature, examples include dormancy, and fnally a second warm period to many desert plants, where the water-soluble, allow shoot growth. In nature, seedlings of plants germination-inhibiting chemicals are leached with these dormancy types will not appear until from the tissues by heavy rains or absorbed by the frst or second spring after the seeds have the soil. Remove these inhibitors by soaking the matured and dropped from the parent plant. seeds in water that is changed daily for several days, or by leaching the seeds in slowly running water for several days (the exact length of time depends on the species). 336 PLANT PROPAGATION chapter 19 In a few other seeds, an immature embryo causes medium well so it is evenly wet, not soggy, dormancy, meaning the embryo is not fully BEFORE flling your container and planting the developed and requires additional growth after seed. the seed is separated from the plant. Examples include: Sowing seeds For large seeds, fll each container to the top • Herbaceous fowers such as ranunculus and and add two to four seeds in holes poked in the poppy. medium. Putting more than one seed per pot will • Woody species such as holly. guarantee one strong plant per pot, especially • Tropical plants such as date palms. if the germination rate is not good, which is possible with some heirloom varieties or seed Seeds with immature embryos often have other saved from a previous year. Normally the planting kinds of dormancy, such as hard seed coats. depth should be four times the thickness of the Alternating warm and cool temperatures will help seed, but consult the seed packet for the proper accelerate embryo growth. planting depth. Starting seeds indoors For smaller seeds, add less mix to the Many plants can be successfully planted directly containers—up to about ¼ inch from the top— in the ground as seeds, but other species do and broadcast the seeds thinly and uniformly much better if started indoors. Environmental over the surface of the mix by gently tapping conditions early in the season in Wisconsin are the seed packet until seeds slowly come out. not often conducive to seed germination. The Consider mixing very small seed with sterile growing season is often too short for certain sand or another fne medium to increase the plants to fully develop from seed if planted when volume and make spreading easier. Then cover conditions are appropriate for germination. Start the seeds with fne, screened soil mix or a layer of transplants several weeks or months before they vermiculite. Extremely fne seed such as begonia, are to be placed outside. petunia, or snapdragon should not be covered Containers but just lightly pressed into the medium. You can use almost any type of container to start seeds indoors, as long as it is sterile, small, and provides good drainage. Many types of plastic or wooden fats have been designed especially for this purpose, but any plastic containers (with A seed starting mix drain holes poked in the bottom), soil blocks, 1 part perlite peat pots, or homemade newspaper pots will work as well. Sterilize any containers that have 1 part peat been previously used for growing plants—soak 1 part sterile potting soil the containers for a couple of minutes in a 10% Mix all together and moisten slightly. bleach solution and thoroughly rinse—to prevent Place mix in an aluminum baking pan plant diseases. or other heat-resistant container and Growing medium bake at 250˚F until the soil temperature reaches 180˚F for 2 hours (the length of Use seed starting mix (see box) or other indoor time to reach this temperature depends planting medium (outdoor soil may have on the volume and moisture content). disease organisms). Soilless planting mixes Remove the pan and allow it to cool are recommended for seed starting. They are before using the mix. lightweight, drain well, do not pack down, and are free of weed seeds and pathogens. You can purchase soilless mixes or create your own (see chapter 13, Houseplants). Moisten the growing 337 UW-Extension Master Gardener Manual: Foundations in Horticulture

After sowing separate the seedlings with as little damage to Cover the seed fats or groups of containers the roots as possible. Handle individual seedlings to keep the seeding medium from drying out. by a leaf, not the stem, so you won’t damage the You can use clear plastic bags, plastic wrap, or stem and kill the plant. Take care that the exposed the clear plastic tops sold with many seed fats. roots of separated plants do not dry before Keep the plastic at least 1 to 1½ inches above planting. Place each seedling a little deeper in the the soil surface. Seeds will germinate best with hole than it was in the seed fat and frm the soil soil temperatures that are much warmer than around the roots. Water the newly transplanted the average home. Constant bottom heat from seedlings gently to settle the soil around the heating tape, cables, or mats placed under the plant. Fertilize seedlings once or twice a week containers will speed germination. with a water-soluble fertilizer and less often if there is soil or fertilizer in the planting medium. Place the covered containers in a location with moderate light, but not in direct sunlight. A Transplants must be hardened of before few seeds, such as delphinium, forget-me-not planting in the garden. Hardening of gradually (Myosotis), phlox, verbena, and violets require acclimates the plant to the wind, more intense darkness to germinate—cover those containers light, and fuctuating temperatures they will be with a piece of cardboard or black paper. Check exposed to outdoors. the containers daily and water as necessary. Keep • Decrease watering and stop fertilizing about the seeds constantly moist but not wet, to avoid two weeks before you plan to plant the disease problems. Water carefully to prevent seedlings in the garden, and, if possible, lower displacing seeds or knocking over tiny seedlings; the temperature slightly to slow growth and misting can be useful here. make the foliage less succulent. As soon as the frst seedlings appear, remove the • Place the plants outdoors in a sheltered plastic cover and artifcial heat and place the pots location or cold frame during this 1- to 2-week in the best available light. Young seedlings need period. intense light more than older plants. • Gradually increase the exposure to sun during • A shelf or windowsill in a sunny, south-facing this time so the plants won’t be sunburned. window may be sufcient for satisfactory • Move plants back indoors temporarily if frost or results, but rotate the pots frequently to other adverse conditions are predicted. prevent lopsided plants. • Reduce watering and withhold fertilizer while • Some supplemental light from ordinary plants are being hardened of. fuorescent lights (grow-lights aren’t necessary) is often benefcial. Asexual propagation: Eighteen hours of light is optimal, but don’t leave lights on all the time—plants need some vegetative darkness to grow normally. Reproduction without genetic recombination After one set of true leaves emerges, transplant is an important, even dominant manner of multiples of seedlings to their own small reproduction for many types of plants. Asexual containers. Individual 2- or 2½-inch pots are large propagation allows us to get exact replicates enough to grow most seedlings to the transplant (clones) of desirable species or cultivars, stage. If you choose to use trays that contain propagate difcult-to-germinate plants, create individual cells, make sure the cells are at least 1½ larger plants faster, or save desirable plants from inches across. disease. Prepare the pots or cells by flling them with soil or a growing mix. Make a deep hole in the growing mix in the center of each pot or cell with your fnger or a pencil. Remove the seedlings from their container in a clump and carefully 338 PLANT PROPAGATION chapter 19 Asexual propagation is the only way to multiply In some cases this is as easy as providing plants that do not produce seed. To increase an appropriate environment, such as roots the numbers of these plants, various methods developing from stem cuttings. A severed coleus involving many diferent plant parts may be used. stem or African violet leaf roots easily when To understand why asexual plant propagation is placed in moist soil, for example. In many other possible, you must know about how plants grow cases, more technical methods—such as tissue and how growth is regulated. culture or treatment with growth regulators— Totipotency and plant hormones must be used to induce plant regeneration. The reason we can produce new plants from A variety of hormones afect plant processes such parts of the parent plant is that plant cells as fowering, aging, root growth, stem elongation, are totipotent (toe-TI-po-tent)—capable of fruit coloration, leaf fall, and many other aspects regenerating an entire organism from a single of the plant life cycle. These small molecules work cell. Each cell possesses all the necessary genetic together in complex, interconnected ways to information to produce a complete new plant, control growth and development. Plants produce but most of the time cells lack the trigger to these hormones naturally, while plant growth change their development. If cells can be induced regulators are extracted hormones or synthetic to switch their development, then new plants can mimics of the natural hormones that humans use be obtained. to afect plant growth. Very small concentrations of these substances can produce major growth changes. The efects of applied plant growth regulators are short-lived, and they may need to be reapplied in order to achieve desired efects. There are fve groups of plant hormones (see table 2), each with its own function in plant growth.

TABLE 2. The fve plant hormones and their functions Hormone Source in plant Major functions in plant propagation Auxin Seed embryo, young leaves, apical bud • Stimulates cell elongation meristems • Involved in phototropism, geotropism, apical dominance, and vascular diferentiation • Stimulates fruit development • Induces adventitious roots on cuttings Cytokinin Synthesized in roots and transported • Stimulates cell division to other organs • Reverses apical dominance • Involved in shoot growth • Delays leaf sequence Ethylene Tissues of ripening fruits, nodes of • Stimulates fruit ripening stems, senescent leaves, and fowers • Promotes leaf and fower senescence and abscission Abscisic acid Leaves, stems, green fruit • Stimulates stomatal closure Gibberellin Meristems of apical buds and roots, • Stimulates cell division and shoot elongation young leaves, embryo • Breaks dormancy and speeds germination • Stimulates bolting and fowering in biennials

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Auxins are one of the most important groups Gibberellins stimulate cell division and of plant hormones for plant propagators. These elongation, break seed dormancy, and enhance hormones are produced in actively growing seed germination. Dwarf plants do not make shoot tips (meristems) and induce and initiate enough active forms of these hormones. adventitious growth of roots. They only move Gibberellic acid is the most commonly used form from the top of stem tissue to the bottom of stem of gibberellins in asexual propagation of plants. tissue (polar transport). Soaking the seeds of some difcult-to-germinate In the stem, auxin is responsible for apical species will get them started. dominance, or suppressing the growth of lateral Cuttings bud meristems. If the apical growing point of the Cuttings are used to propagate many types of plant is removed, the remaining buds will grow plants—both woody and herbaceous. A cutting because of reduced auxin. is a vegetative plant part that, when removed Auxin is important in the formation of from the parent plan, will produce adventitious adventitious growth of both roots and shoots, growth of lost parts to form a whole new plant. or growing in an atypical location during normal Rooting cuttings is an easy way of propagating growth. It is the active ingredient in most rooting many plants and saving some garden plants, such compounds in which cuttings are dipped during as geraniums and impatiens, over the winter. vegetative propagation. Successful home propagation of plants relies Auxins also play a role in phototropism, or on providing the appropriate propagation movement towards light. Sunlight degrades environment for each particular plant. To do auxin, so the part of the shoot tip of the plant so, you can manipulate various environmental receiving direct sunlight will have the least factors, including moisture, temperature, light, amount of auxin. The higher concentration of and the propagation medium. auxins on the shaded side promotes more cell • Moisture (humidity) is essential to prevent division and elongation, causing the plant to desiccation in plants that are regenerating bend towards the sunlight through lopsided root systems; regulate this with your choice of growth. One of the most common auxins is planting medium, by misting, or by placing a indole acetic acid (IAA). The most commonly used lid over the container. auxin for asexual propagation and adventitious • Temperature afects cell respiration and rooting is indole-3-butyric acid. growth; use bottom heat to stimulate root Cytokinins stimulate cell division and are often regrowth. included in sterile media used for growing plants • Balance natural and artifcial light sources with from tissue culture. moisture and temperature. Abscisic acid (ABA) is a general plant-growth Plant parts used in asexual propagation are often inhibitor that induces dormancy and prevents embedded in some form of substrate, or medium, seeds from germinating, causes abscission for support and to hold moisture. A rooting (shedding) of leaves, fruits, and fowers, and medium should be sterile and low in fertility, causes stomata to close. should drain well enough to provide oxygen to Ethylene, found only in the gaseous form, newly forming roots, and should retain enough induces ripening and promotes senescence. moisture to prevent water stress. Increased ethylene in leaf tissue in the fall is part Materials most often used are coarse sand, of the reason leaves fall of trees. perlite, vermiculite, peat moss, and sphagnum moss; each has advantages and disadvantages. Propagation mixes that combine these materials are commercially available. Water is generally not a good medium for rooting because sufcient

340 PLANT PROPAGATION chapter 19 oxygen can’t reach developing roots and any 5. Place the container in a warm area (65 to 75˚F) roots that do develop are fragile and may not where it will receive plenty of light but no transplant well. direct sunlight. Open the bag or lid every day Leaves, stems, or root cuttings may be used as for a few minutes to allow fresh air to reach the cutting sources, depending on the plant species cuttings and to prevent mold from forming. (see table 3). The length of time needed for roots to form depends on the kind of plant, the temperature, TABLE 3. Plants for cuttings and other factors. Many kinds of houseplants Herbaceous coleus, chrysanthemum, will root in 10 to 21 days; some woody plants stem dahlia, fuchsia, geranium, may require months. impatiens, phlox, Russian sage, salvia, sedum, vinca 6. Transplant the cuttings when their roots are Softwood stem azalea, boxwood, English about 1 inch in length. Carefully lift the plants ivy, lilac out of the rooting medium to avoid damaging Semi-hardwood Cotoneaster, euonymus, the new roots. Water them thoroughly after stem juniper, serviceberry potting and leave them in indirect light for a Hardwood stem forsythia, hydrangea, week to ten days until new growth begins. rhododendron, rose, spirea, weigela, and many Specifc stem, root, and leaf cutting techniques evergreens (holly, fr, pine, follow. and spruce) Root anemone, gaillardia, phlox, Stem cuttings yucca Numerous plant species are propagated by stem Leaf African violet, begonia, cuttings, especially woody ornamentals (fgure 3). Sansevieria, Streptocarpus Some can be taken at any time of the year, but stem cuttings of many woody plants must be The general process for taking a cutting is: taken at specifc times during their growth cycle. The four main types of stem cuttings are 1. Take cuttings with a sharp blade and wash herbaceous, softwood, semi-hardwood, and any dirt of of the plant part to minimize hardwood. pathogens. FIGURE 3. Taking a stem cutting 2. Remove any fowers, fower buds, or fruits so the cutting will direct its energy and stored carbohydrates for root and shoot formation rather than fruit and seed production. Reduce the area of large leaves to lower water loss from the plant part. 3. Dip the area you wish to root in a rooting hormone, preferably one containing a Herbaceous cuttings are made from non- fungicide, to increase the success or speed of woody, herbaceous plants such as coleus, rooting. Insert the cuttings into moistened chrysanthemums, and dahlias. Cuttings should rooting medium and keep the medium evenly be about 3 to 5 inches long and should be taken moist while the cuttings are rooting and just below a leaf. Remove the leaves on the lower forming new shoots. one-third to one-half of the stem, leaving three 4. Place a plastic bag over the entire rooting to four leaves on the upper portion of the cutting container and lightly fasten it to help maintain for the best rooting. A high percentage of the high humidity (or use a special rooting cuttings should root quickly. chamber with a plastic top).

341 UW-Extension Master Gardener Manual: Foundations in Horticulture

Softwood cuttings are prepared from soft, FIGURE 4. A root cutting succulent new growth of woody plants, just as the growth begins to harden. Actively growing shoots are suitable for making softwood cuttings when they can be snapped easily when bent and the newest leaves are still small and not mature. This stage typically occurs in May, June, or July. The soft shoots are quite tender, and extra care must be taken to keep them hydrated. Semi-hardwood cuttings are taken from partially mature wood of the current season’s growth, just Select roots that are 1⁄8 to ½ inch in diameter and after a fush of growth, generally from mid-July cut them into segments 1 to 4 inches long. Sand to early fall. The wood is reasonably frm—it is the most common medium for rooting indoors; bends but snaps only when bent to an angle of you can also place the cuttings directly into soil 70 to 80 degrees—and the leaves have reached for propagation outdoors. Insert the cuttings of their mature size. Many broadleaf evergreen plants with small roots horizontally about ½ inch shrubs and some conifers are propagated by this below the medium surface. Place larger roots method. vertically with the top approximately level with Hardwood cuttings are taken from dormant, the surface of the rooting medium. Maintain high mature stems in the late fall, winter, or early humidity in the rooting container until shoots spring when there are no signs of active appear. growth. The wood is frm and does not bend Leaf cuttings easily. Hardwood cuttings are used most often Leaves, taken as cuttings from most plants will for deciduous shrubs such as forsythia and produce a few roots but no plant—or just decay. spirea, but can be used for many evergreens. But a few herbaceous or succulent indoor plants The cuttings should be stored in cool, moist will regenerate shoots and roots from a single conditions to produce a callus. Plant the cutting leaf. African violet, Sansevieria, begonias, and so that two nodes are below the soil line and one Streptocarpus are commonly propagated by leaf node is above the soil line. cuttings. Root cuttings Whole leaf cuttings of plants with the petiole Any plant that will sprout from root sections intact form one or more new plants at the base can be propagated by root cuttings (fgure 4). of the petiole (fgure 5). For plants with sessile Cuttings are usually taken from two- to three- leaves (no petiole), the cutting forms a new plant year-old plants during their dormant season. from the auxiliary bud. The leaf may be removed Root cuttings of some species produce new when the new plant has its own roots. shoots, which then form their own root systems, FIGURE 5. A leaf cutting while other plants develop root systems before producing new shoots.

342 PLANT PROPAGATION chapter 19 Leaf sections are often used for Sansevieria and Modifed stems fbrous rooted begonias. Many plants reproduce themselves vegetatively • Cut Sansevieria leaves into 2-inch sections, by developing specialized structures modifed making the lower cut slanted and the upper from stems in a variety of ways. Typical stems are cut straight (so you can tell which is the top), aboveground trunks and branches, but in many and insert these cuttings vertically with the cases modifed stems form above or below the basal end of the cutting inserted into the ground and develop to form diferent types of rooting medium. Roots will form fairly soon, vegetative reproductive structures or storage and eventually a new plant will appear at the organs. base of the cutting. Note that these and other • Aboveground modifed stems include crowns, succulent cuttings will rot if kept too moist. stolons, and runners. • Cut begonia leaves into wedges with at least • Belowground modifed stems include bulbs, one vein and lay leaf pieces fat on the rooting corms, rhizomes, and tubers. medium. A new plant will arise at the vein. Aboveground Division and separation Crowns are compressed stem tissue at the One of the easiest and quickest means of plant surface of the ground from which new shoots are propagation is separating a plant into sections produced. In herbaceous perennials, the crown (division) or by removing natural ofsets from the consists of many branches originating from the parent plant (separation). Gardeners commonly base of the preceding year’s branch. Adventitious refer to both means of plant propagation as roots develop along the base of the new shoots. division. As a result of the annual production of new Division is only efective with certain plants shoots and dying back of old shoots, the crown that multiply vegetatively, such as hostas and may become quite large within just a few years. daylilies (fgure 6). Division cannot be used for Most of the clump-forming herbaceous plants with a single stem, and it difers from perennials such as irises, daylilies, and hostas taking cuttings in that the new plants already develop a large crown with multiple shoots. have both roots and shoots. A few plants produce Some of these must be divided every 2 to 3 ofsets, a characteristic type of lateral shoot or years to prevent the plants from becoming branch that develops from the base of the main overcrowded. It’s best to divide these herbaceous stems, but many others have modifcations of perennials in early spring just before growth their vegetative structures (stems and roots) that begins or in late summer or fall at the end of the allow for natural increase and are often used for growing season. As a general rule, divide spring propagation. and early summer bloomers in the fall, and divide FIGURE 6. Plant division summer and fall bloomers in spring. To divide: • Dig up the whole clump and separate it into sections. If the stems are not joined, gently pull the plants apart with your hands. • If the crowns are attached by horizontal stems or the roots are inextricably entwined, cut the stems and roots with a sharp knife or shovel. • Separate the clump into individual plantlets, each with some roots and a tuft of leaves. Try to follow the natural path of least resistance, shaking of surplus soil to make it easier to pull the clump apart.

343 UW-Extension Master Gardener Manual: Foundations in Horticulture

• Carefully replant each division and keep them FIGURE 7. Cross-section of a bulb well watered until the plants are re-established, usually in about 4 to 6 weeks. Divide multi-branched woody shrubs in the same manner when they are dormant—you may need a hatchet to divide the crowns. Cut back the tops and trim the roots at the time of division and plant each section as a new shrub. Stolons and runners are horizontally growing modifed stems with long thin internodes (and no storage in the stem) that are produced above the ground. There is a distinct basal plate on each bulb, • A stolon produces adventitious roots, generally which is a compressed stem and the primary when in contact with the soil, and then growing point for the bulb during initial phases produces new shoots at that point. Spider of regrowth. The feshy scales protect the growing plants and many grasses produce stolons. point in the bulb. • A runner is just another name for a stolon. • Tunicate bulbs have layered fat, feshy Strawberries and ajuga are examples of plants leaves and are further protected by an outer whose stolons are commonly called runners. membrane, called a tunic. The tunic is relatively FIGURE 6. Horizontal modifed stem thin and dries after the bulb is harvested, creating a membranous-type covering. Onions and tulips are examples of tunicate bulbs and are better protected from drying and mechanical damage than nontunicate bulbs such as lilies. • Scaly (or nontunicate) bulbs, such as lilies, have clusters of enlarged, feshy leaf scales but no tunic (papery covering) to protect the scales (fgure 8). Remove individual feshy scales from To propagate new plants from plants that a mature bulb and root them to create new produce stolons or runners, sever the new plants plants. A scaly bulb can also be cut into several from their parent stems. New plants at the tips vertical sections—each containing a part of of runners may be rooted while still attached the basal plate—and planted to produce new to the parent (they can be set into the soil and plants after you’ve allowed the cut edges to dry pegged down to speed up the rooting process), and cure. or detached and placed in a rooting medium. FIGURE 8. Scaly bulb Belowground Bulbs are a dormant shoot system with a short, feshy vertical stem enclosed by thick, feshy modifed leaves, usually termed scales or bulb scales (fgure 7). Some plants with true bulbs include amaryllis, lilies, dafodils, onions, scilla, and tulips.

344 PLANT PROPAGATION chapter 19 Bulbs produce side branches in the axils of the Rhizomes are non-feshy underground horizontal bulb’s leaves called bulblets. Both the bulblets stems that are distinguished from a root by the and the primary bulb increase in size with age presence of nodes and internodes (fgure 10). to produce a clump of bulbs after a few years. To Unlike true roots, rhizomes have nodes, buds, divide bulbs, dig up the clump after the plants and tiny leaves and do not die when cut from the have gone dormant. Separate the new bulbs from parent plant. Upright, aboveground shoots and the parent bulb and replant them. fowering stems are produced either terminally A corm is a compact, belowground, feshy stem from the rhizome tip or from lateral branches. modifed into a mass of storage tissue. Unlike Most plants with rhizomes are monocots and a true bulb, the solid stem has distinct nodes include iris, horsetails, many ferns, lily of the and internodes and papery leaves. Examples of valley, and many grasses. plants with corms include crocus, elephant ears FIGURE 10. Rhizome (Colocasia), and gladiolus. A corm does not have visible storage rings when cut in half, but corms are frequently (and mistakenly) called bulbs. Corms produce both fbrous roots for water and nutrient absorption, internode and enlarged roots for support and to pull the node { corm deeper into the soil for more uniform temperatures. Corms propagate by forming cormels, miniature corms developed from buds that originate in the axils of the corm’s leaves, around the base of the Propagate these plants by clump division before new corm (fgure 9). Propagate these plants by or after a growth period. Cut rooted sections separating the cormels from the primary corm. of, making sure that each piece has at least one Dig up the plants after the foliage dies back, lateral bud (or eye), and replant them. If rhizome- shake of the soil, and let them dry in indirect producing grasses, such as quackgrass, are cut or light for 2 to 3 weeks. Remove the cormels and broken into pieces, such as by tilling, new plants gently separate the new corm and store them in will develop at almost all intact nodes. a cool place until planting time. Cormels usually Tubers are localized, feshy swellings of a require an additional 1 to 2 years’ growth before portion of the stem with nodes and axillary fowers are produced. buds (eyes). Tubers are nutrient storage organs FIGURE 9. A corm with cormels that allow for survival during dormant periods. Long photoperiods encourage shoot growth of tuberous plants, while reduced day length, lower night temperatures, and lower mineral nutrition encourage tuber development. Two of the best- known tubers are the Irish potato and caladium; some begonias, oxalis, and anemones are other plants with tubers. Propagation of tubers involves either planting the entire tuber or cutting the tuber into pieces, each containing one to three buds. Dig up the tubers after the foliage dies back. If you cut the tubers into pieces, allow them to dry before planting.

345 UW-Extension Master Gardener Manual: Foundations in Horticulture

Suckers are shoots that arise from an Layering adventitious bud on a root or from the vicinity of Layering is the process of causing adventitious the crown. The tendency to sucker is an innate root development on a stem still attached to characteristic of some plants such as lilacs, the parent plant. Once severed from the parent poplars, and sumac. plant, the rooted stem becomes a new plant. This Suckering and the ability to grow plants from method generally has a high success rate because root cuttings are closely related. Suckers can be the developing new plant has a continuous water dug out and cut from the parent plant; pulling and nutrient source that cuttings do not. A few the sucker may injure its base and reduce its plants layer themselves naturally, but this type chances for survival. Treat the sucker the same as of vegetative reproduction may also be induced you would a rooted cutting since new roots often artifcially in many kinds of plants. Several are not yet formed. Most suckers should be dug procedures utilize diferent stem treatments to when the plant is dormant. encourage the formation of roots. Modifed roots Tip layering Certain herbaceous perennials such as dahlia, Tip layering mimics a natural method of gloxinia, sweet potato, and tuberous begonia vegetative reproduction in purple and black have roots modifed for nutrient storage. These raspberries and trailing blackberries. Bury the tuberous roots have the internal and external tip of a cane in a shallow hole 3 to 4 inches deep features of a typical root but are generally greatly (fgure 12). The tip will grow downward frst and enlarged or swollen (fgure 11). They difer from then should bend sharply and grow upward. true tubers in that they lack nodes and axillary Roots form at the bend, and the recurved tip buds. Buds are normally present only on the becomes a new plant. Remove the tip layer by proximal (shoot) end, unlike true tubers, which cutting below the zone of rooting and plant it in can have “eyes” on all parts of the tuber. the early spring or late fall. FIGURE 11. Tuberous roots FIGURE 12. Tip layering

Most tuberous roots are incapable of producing adventitious shoots and must be divided so each piece contains a shoot bud; sweet potato is an Simple layering exception and can produce adventitious shoots. This method involves bending a low growing, To propagate tuberous-rooted plants, divide the fexible stem to the ground and covering a crown into sections with an eye-bearing portion portion of it to induce rooting (fgure 13). Simple of the stem left with each section of the root. layering can be done on many plants with low- Division should be done at planting time, not growing branches. Some plants that can easily before placing in storage in the fall. be propagated by simple layering include azalea, boxwood, climbing roses, forsythia, honeysuckle, rhododendron, and most vine-type plants such as philodendron, grape ivy, pothos, and Swedish ivy.

346 PLANT PROPAGATION chapter 19 FIGURE 13. Simple layering FIGURE 14. Compound layering

Simple layering is best done in the early spring Mound layering using a dormant branch or in the late summer The mound (or stool) layering method is useful using a mature branch. with heavy-stemmed, closely branched shrubs • Bend the stem to the ground and cover part such as cotoneaster, magnolia and spirea, and of it with soil, leaving the last 6 to 12 inches tree fruit rootstocks (fgure 15). exposed. • Before new growth starts, cut the parent plant • Just bending the tip sharply into a vertical back to 1 inch above the soil surface. Dormant position and staking it in place will often buds will produce new shoots in the spring. induce rooting; however, wounding the lower • When the new shoots are 3 to 5 inches high, side of the branch or loosening the bark by mound soil around the lower half of the shoot. twisting the stem may be necessary in some • Make a second mound of soil when the shoots cases. are 8 to 10 inches tall and a fnal mound when • Periodically check for the formation of roots. they are about 18 inches high. Cover the base Depending on the plant, it may take one or of the shoots with 6 to 8 inches of soil. more seasons before the layer is ready to be • Roots will develop at the bases of the young removed for transplanting. shoots, generally by the end of the growing Compound layering season. This method is essentially the same as simple • Remove the layers in the dormant season. layering, but the branch is alternately covered FIGURE 15. Mound layering and exposed along its length to produce several layers from a single stem (fgure 14). Compound (or serpentine) layering works well for plants producing vine-like growth such as clematis, grapes, heart-leaf philodendron, pothos, and wisteria. Bend the stem to the rooting medium as for simple layering, but alternately cover and expose sections of the stem. Each section should have at least one bud exposed and one bud covered with soil.

After these layers have been cut away, the parent plant can be left exposed and used again for mound layering the next season. 347 UW-Extension Master Gardener Manual: Foundations in Horticulture

Trench layering • Wound the stem by either slitting the stem just This method is used primarily for woody species below the node and prying open the slit with that are difcult to propagate by mound layering, a toothpick or removing a ½- to 1-inch strip of such as currents, gooseberries, mock orange, bark from around the stem. and cranberry viburnum. A plant or branch of a • Surround the wound with a handful of wet plant is grown in a horizontal position in the base sphagnum moss—soak it in water frst and of a trench (fgure 16). The trench is gradually squeeze it to remove excess moisture. flled with soil as new shoots develop, so the • Wrap plastic or foil completely around the moss shoot bases are elongated. Roots will eventually and tie or tape it securely in place to retain develop from the base of these new shoots. moisture. An established plant can be trench-layered by burying a low, fexible shoot to the ground—as • Auxin is sometimes applied to woody plants with simple layering, but covering the entire being air layered at the site of wounding to length. stimulate root development. FIGURE 16. Trench layering • After the moss is flled with roots, sever the stem below the roots and pot the layer. FIGURE 17. Air layering

Air layering This method is used to propagate a number of tropical indoor plants with rigid stems such as Grafting and budding Grafting and budding are methods of asexual aralia, croton, diefenbachia, fcus, and rubber plant propagation that join two pieces of living plant, or to rejuvenate them when they become plant tissue so they will grow and develop as leggy or have lost most of their lower leaves. one plant. Budding is similar to grafting, but the Woody ornamentals such as azalea, camellia, shoot portion is reduced to a single bud. These magnolia, and holly can also be propagated by air techniques are used to propagate cultivars that layering. will not root well as cuttings, whose own root Air layering is seldom used on plants that root systems are inadequate, or will not come true easily by other more simple methods. For from seeds, and in some cases to produce dwarf optimum rooting, make air layers in the spring on plants by using special understocks. shoots produced during the previous season or in Although grafting usually refers to joining two mid- to late summer on shoots from the current plants, it may be a combination of several. season’s growth. For woody plants, stems of Multiple grafts can produce a fruit tree with pencil size diameter or larger are best (fgure 17). several varieties or an ornamental plant with • Choose an area about 1 foot from the growing several diferent colors of fowers. Although many tip, just below a node, and remove any leaves types of plants technically can be grafted, this is or twigs on the stem 3 to 4 inches above and typically only done with woody plants. below this point.

348 PLANT PROPAGATION chapter 19 Not all plants can be grafted together. Generally, For successful grafting to occur, fve conditions only plants that are closely related botanically must be met: will form a good graft union and they must be • The scion and understock must be compatible. compatible. The compatibility of plants has been • Each must be at the proper physiological stage. determined through many years of trial; this type of information is available in many publications. • The cambium of the scion and stock must Most cultivars of a particular fruit or fowering meet. species can be grafted, and plants of the same • The graft union must be kept moist until the species can usually be grafted even though they wound has healed. are a diferent cultivar. Due to diferences in vigor, • The plant must be given proper care for a some are better suited than others. Plants within period of time after grafting. the same genus can sometimes be grafted; plants of diferent genera are less likely to be grafted The best time for grafting is in late winter or early successfully. spring before new growth begins, preferably after the chance of severe cold has passed but Grafting has its own specifc terminology for the well before hot weather arrives. Scion wood may plant parts used (fgure 18). be collected during the winter and stored in a • The scion is the upper portion that becomes cold, moist place at temperatures close to 34˚F, the top of the plant. It consists of a piece of such as in a plastic bag in the refrigerator with shoot with dormant buds that will produce moist paper towels. After the graft has taken and the stem and branches. Scion wood should be growth of the scion has started, cut of any side made of ¼- to 3⁄8-inch diameter twigs from the shoots or competing twigs that would shade or previous season’s growth, with two to three compete with the development of the new graft, buds each. as well as any regrowth on the rootstock portion. • The understock, or rootstock, is the lower Grafting methods can be divided into two basic portion and provides the new plant’s root types, which are largely determined by the size system and sometimes the lower part of the of the understock. One type joins a scion and stem. It may be a seedling, a rooted cutting, a understock of nearly equal size. Whip (bench) layered plant, or a well-established plant. grafts and splice grafts are two common types. FIGURE 18. Grafting terminology The other type attaches a small scion to a much larger understock. In this case, several scions may be attached to the understock. Some common types include the cleft graft, bark (veneer) graft, and side (stub) graft. Specifc procedures for these and other types of grafting can be found in many publications. Plant micropropagation scion Plant tissue culture refers to the ability to establish and maintain in aseptic culture plant organs like embryos, shoots, roots, and fowers bud-graft and plant tissues like cells, callus, and protoplasts union to regenerate new plants. The various procedures used collectively are referred to as tissue culture, rootstock organ culture, in vitro culture, micropropagation, or biotechnology. Tissue culture is based upon the principle of cell totipotency; without cells being totipotent this means of propagating plants would not be possible.

349 UW-Extension Master Gardener Manual: Foundations in Horticulture

Micropropagation is a powerful means by which rooting occurs. Through manipulation of these plants can be rapidly increased to hundreds of hormones, shoots or roots form and subsequently thousands of plants in a matter of months. The an intact plant becomes established. technique is time-consuming, expensive, and not Micropropagation success involves four suited economically for all plants. Additionally, developmental stages. genetic instability can occur on some plants, 1. Stage I is establishment and stabilization of resulting in permanent genetic change or a the explant (plant part being cultured). The transient genetic change that will correct itself function of this stage is to disinfest the explant, over time. Many of the newer plants you use establish the explant on the culture medium, in your gardens may have been developed, and stabilize the explant for multiple shoot improved, or multiplied directly or indirectly proliferation. using the techniques of micropropagation. Some examples of common plants propagated by 2. Stage II is shoot multiplication. In this stage tissue culture include deciduous and evergreen the explant proliferates into a cluster of shoots azaleas, daylilies, hosta, peace lily, diefenbachia, (microshoots) arising from the explant. This and many more. proliferated structure is divided into separate microshoots, which are then subcultured to Micropropagation of plants is used widely in the new culture medium. The process is repeated agriculture and horticulture industries for rapid many times until the desired number of plants increase of elite plant genotypes or cloning a is achieved. During this stage, the level of plant, disease elimination, plant screening for cytokinin is maintained at a higher level than diseases and insects, plant breeding, genetic auxin so microshoots form. engineering of plants, and production of certain plant products. Its economic importance was 3. Stage III is root formation. Microshoots do not realized frst in the early 1970s and the impact of usually have roots. The hormones are altered in this technique has continued to increase over the this stage so the level of auxin exceeds the level years. While it can be technically sophisticated, of cytokinin and roots form. you can do micropropagation in your own home 4. Stage IV is acclimatization. In this stage, rooted with the proper materials and techniques. microshoots are gradually acclimated to normal The process of micropropagation is done in growing conditions. Rooted microcuttings conditions where the plant tissue or organ is are removed from the culture vessel, culture cultured under sterile conditions in a sealed medium is washed from roots, and plantlets container on a liquid or gel medium containing are transplanted into pasteurized medium and plant nutrients, vitamins, a sugar source, and grown under reduced light and high humidity. plant hormones. Various types of media are Over a period of several weeks to months used depending on the type of plant or plant microcuttings are adapted gradually to normal part being cultured. The environment for tissue environmental conditions and grown to larger, culture is important and based on the needs of sellable plants. the type of plant being cultured. The manipulation of two plant hormones, auxin and cytokinin, is crucial to success in micropropagation. These hormones, discussed earlier in this chapter, work together in forming shoots or roots depending on the balance between the two hormones, which will vary depending on the type of plant. When the level of cytokinin exceeds the level of auxin in plant tissue, shoots proliferate. In the reverse situation, when auxin level exceeds the cytokinin level, 350 PLANT PROPAGATION chapter 19 Conclusion Plants have various natural reproductive strategies. Gardeners can use knowledge of plant FAQs biology to manipulate the environment to create more plants, preserve desired traits, or make Can I save seeds from my fowers? How plants grow more vigorously. Seed starting results ?long can I keep them? in plants that may be genetically distinct from its Yes. Realize that seeds from hybrid parents and asexual, or vegetative, techniques plants are not likely to have the same create new plants that are genetically identical characteristics as the parent—but heirloom to the parent plant. There are many techniques varieties will. Most seeds will keep for for propagating plants, and success varies from several years if stored under cool, dry gardener to gardener, as well as plant species conditions, with some exceptions. Viability to plant species. Propagation is an intriguing declines with age. combination of science and horticultural Why aren’t my seeds growing? technique that is accessible to all. ?A lot of factors afect seed germination. The seed coat could be too hard, the seed Resources could be too dry or old, the soil could be UW-Extension resources too cold, or a critter or fungus could have damaged it. Double-check the seed packet UW-Extension publications are available at instructions to ensure the soon-to-be learningstore.uwex.edu. seedlings have the right start. • Collecting and Planting Seeds of Cone-bearing What can I take a cutting from? Trees (G1649) ?It depends on the plant. Some plants • Growing and Using Annuals and Bulbs (NCR399) are easily propagated from the stems, • Plant Propagation Techniques (NCR274) others from roots, and others from a • Rootstocks for Fruit Trees in Wisconsin (A3561) single leaf. Some plant cuttings are very difcult to root. Take cuttings at just the Wisconsin Horticulture publications are right developmental stage and keep under available at hort.uwex.edu. specifc environmental conditions. Wisconsin Master Gardener Program wimastergardener.org When do I divide my hostas? The best time is early spring before Your County Extension ofce ? the leaves emerge—but they can tolerate counties.uwex.edu division almost any time except when the ground is frozen. Other resources Home Propagation of Garden and Landscape Plants http://extension.missouri.edu/p/g6970

MGVs: These resources are also online @ http://goo.gl/ygkkAt. 351 UW-Extension Master Gardener Manual: Foundations in Horticulture Plant propagation, practice exam questions 1. Which of the following is true about d. Is produced in the meristems of 10. The method used to break internal plant breeding? shoot tips dormancy by exposing seeds to a. Humans have been doing it for e. All of the above moisture and cold temperatures for thousands of years a period of time is called 6. The fnal step in seed starting when a. Scarifcation b. The goal is to develop plants with transplants are acclimated to desirable characteristics wind, intense light, and fuctuating b. Stratifcation c. Genetic engineering is a type of temperatures is called c. Sporifcation plant breeding a. Propagation d. Californication d. All of the above b. Exposure acclimation 11. This seed type is known for its 2. Which is NOT a type of asexual c. Weather acclimation vigor, high yield, disease resistance propagation? d. Hardening of and uniformity a. Layering a. F1 hybrid 7. What plant part cannot be b. Micropropagation propagated asexually by cuttings? b. F2 hybrid c. Leaf cuttings a. Stem c. Inbred lines d. Growing from seeds b. Leaf d. Seed mixes 3. Plant cells are totipotent. This means c. Root 12. The following is TRUE about a. They lyse when put in water d. None of the above micropropagation a. Plants are propagated in sterile b. Plants can regenerate an entire 8. Corms, bulbs, tubers, rhizomes, conditions plant from a single cell stolons and runners are all modifed c. Plant cells divide uncontrollably in ______tissue b. It can only be used for very small the presence of ethylene a. Stem plants d. They contain auxin b. Leaf c. Plant hormones auxin and cytokinin play an important role in 4. Pollination is c. Root micropropagation a. The transfer of pollen to the d. None of the above female fower parts d. All of the above 9. Which of the following is FALSE e. a and c b. The union of the male and female about grafting? reproductive material a. Only closely related, compatible c. Only done by insects plants can be successfully grafted d. a and c b. The scion is the term for the 5. Which of the following is TRUE about portion of the plant below the the hormone auxin? bud-graft union a. Is responsible for apical c. It is typically done with woody dominance plants b. Is the active ingredient in rooting d. The best time to graft is in late compounds winter or early spring c. Promotes adventitious root formation

Answer key 1. (d) 2. (d) 3. (b) 4. (a) 5. (e) 6. (d) 7. (d) 8. (a) 9. (b) 10. (b) 11. (a) 12. ( e) 352 Glossary

UW-EXTENSION MASTER GARDENER MANUAL: FOUNDATIONS IN HORTICULTURE abdomen aerobic anther balled and burlapped One of three main insect Occurring in the presence of Pollen bearing structure in Trees and shrubs dug with body parts whose functions oxygen; aerobic organisms fowers soil around their roots; the are mainly digestive, require oxygen to respire apical dominance roots are then wrapped in respiratory, and reproductive and live Suppression of the growth burlap and may be encased abiotic disorder aggregate fruit of lateral bud meristems, in a wire or similar basket Plant disorder in which no Fruit that develops from caused by auxin bare root microorganism is involved a single fower with many arthopod Trees and shrubs generally abscisic acid ovaries Phylum that includes dug from nurseries in the fall, A plant hormone that aggregate insects, spiders, mites, and held in climate-controlled promotes leaf detachment, Individual particles in soil crustaceans, such as crayfsh coolers over the winter, and then sold bare, without soil, induces seed and bud organized into small clods asexual reproduction in the spring dormancy, and inhibits allelopathy Reproduction without germination, also called ABA The suppression of growth of genetic recombination; basal plate abscission one plant species by another natural cloning; vegetative Bottom of bulb from which Leaf drop due to the release of toxic propagation/reproduction roots grow abscission layer substances augmentation biennial Layer of cells that forms at alternate host Periodic release of natural A plant that requires all or the base of fruits, fowers, In plant pathology, one enemies of pests to part of two growing seasons and leaves before they of two species of host on supplement existing ones to complete its life cycle naturally fall of which some pathogens, auxin biennial bearing acclimatization such as rust, must develop to A growth-regulating plant When fruit trees produce a Plants adjusting to a new complete its life cycle hormone involved in large crop one year and a environment through alternate leaves phototropism, geotropism, small crop the next gradual chemical and Leaf attachment with only apical dominance, fower binary fssion physiological changes one leaf per node formation, fruit set and Simple process in bacteria by actinomycetes anaerobic growth, and adventitious which they reproduce A group of bacteria Occurring in the absence of root formation biocide characterized by a grey, oxygen; anaerobic organisms axil Substance that is toxic to all cobwebby growth and an do not require oxygen to The angle between the stem kinds of biological organisms earthy smell respire and live and the leaf petiole biopesticide active ingredients analogous colors axillary Pesticides derived from The chemicals in pesticide Colors that are adjacent on Buds or growth located in natural materials including products that kill, control, or the color wheel axils animals, plants, bacteria, and repel pests anion bacterial streaming certain minerals adventitious buds/growth Atom or group of atoms Phenomenon in which biotic disease Buds that arise at sites other carrying a negative electric bacteria can be seen to Disease caused by than the terminal or axillary charge visibly stream out of the cut microorganisms position, such as a stem annual vein of an infected plant internode or edge of a leaf A plant that completes its life bactericide blade, that allow for stem, cycle in one year Pesticide that kills bacteria leaf, and root cuttings to develop into entirely new plants 353 UW-Extension Master Gardener Manual: Foundations in Horticulture

blight candle complete fower Disease caused by bacteria or The new, soft growth on pine A fower with a stamen, pistil, fungi that afects large sections trees petals, and sepals of leaves or whole plants, often cane complete metamorphosis with rapid discoloration and Stem with relatively large pith Insect development with four tissue death that usually lives only one or two distinct life stages: egg, larva blossom end rot years pupa, adult Disorder caused by insufcient canker compost calcium uptake, generally due to Localized necrotic area on plant End product of composting; a irregular soil moisture levels stems, branches, or trunks caused humus-rich soil amendment Bordeaux mix by fungi or bacteria, often sunken compost tea A fungicide containing water, or raised and surrounded by A liquid infusion made from lime, and copper sulfate healthy tissue compost that contains nutrients boric acid capsaicin and microbes A compound derived from borax Repellent derived from hot compound leaves used as an organic pesticide for peppers that can deter some Several separate leafets arising some crawling pests insects from the same petiole botanicals catfacing conservation Pesticides derived directly from Disfgurement or malformation of Biological control method that plants and plant products fruits due to low temperature or encourages the activities of brooming insect feeding naturally occurring benefcial Abnormal production of cation organisms by preventing excessive branches from a single Atom or group of atoms carrying their destruction or providing point on a branch a positive electric charge additional resources Bt cation exchange capacity containerized Naturally occurring bacterium A measure of the number of Trees and shrubs sold in pots Bacillus thuringiensis that is negative charge sites in a soil, core aerate used as a common microbial and thus its ability to hold A process that removes a core or insecticide cations, that can be used as an plug of grass and soil from a lawn budwood index of potential soil fertility alleviating soil compaction Short shoots or young branches central leader corm with buds suitable for bud The main vertical trunk of a tree A storage organ comprised grafting chlorophyll of a swollen, compressed bulbil The pigment, found in underground stem Small bulblike structure chloroplasts, that makes leaves cormel produced in the place of a fower green and is responsible for Cluster of small corms that form or in a leaf axil photosynthesis around the base of a corm bulblet chloroplast corn gluten meal A small bulb arising from another Very small structure in mesophyll Dried residue of processed corn bulb cells where photosynthesis takes used as a natural pre-emergent callus place herbicide A mass of hard protective tissue chlorosis corolla produced in woody plants at the Yellowing of the leaves or other A collective term for petals site of an injury plant parts cortex calyx color break Cells in roots that may be A collective term for sepals Striping or streaking symptom in modifed for storage of sugars fowers caused by viruses cambium cotyledon A layer of quickly dividing cells, complementary colors Specialized leaf that supplies a between the wood and bark in Colors directly opposite on the seedling with initial energy for trees, where new growth appears color wheel growth 354 GLOSSARY cover crop cyme dormant/dormancy Plants grown primarily for their Inforescence in which top forets An inactive state during which utility as living mulch, not food or open frst and bloom progresses growth and development cease aesthetics downward along the stem and metabolism is slowed, crop rotation cytokinin often in response to an adverse Intentional planting of crops in Growth regulating hormone environment diferent locations each year to found in both animals and plants double digging reduce populations of certain that stimulate cell division Process of improving the soil by insects and microbial soil damping of incorporating amendments to a pathogens, or to manage soil Disease caused by diferent much deeper level than normal fertility pathogens that kills seedlings digging or tilling accomplishes cross-fertilization deadheading double dormancy In which genetic information Removing old blossoms A combination of seed coat and from two parent plants is internal dormancy defoliation combined Removal of leaf tissue or dripline crotch complete leaf loss The area directly under the The angle between the tree outer circumference of a tree’s degree days branch and the trunk branches A measurement incorporating crown both temperature and time to drupe Multiple stems emerging from a quantify the rate of plant or Fruit that consists of a feshy point insect development exterior and a single, hard seed cultivar determinate drupelet A contraction of “cultivated Growth habit in which apical One of the small individual variety;” a distinct variety of plant growth terminates in an drupes forming a feshy that originated and persists only inforescence aggregate fruit in cultivation (not in nature) diatomaceous earth elytron (pl. elytra) cultivation Powdered remains of diatoms Hardened forewing in some Tilling or turning soil to prepare insects dicots a site A group of plants, also known as embryo cure dicotyledons, whose seed has The part of a seed in an arrested A resting process for compost to two cotyledons state of development that will become stable and mature develop into a plant when dioecious conditions are favorable cuticle Having male and female fowers In leaf blades, the part of the on separate plants endosperm epidermis that produces cutin Nutritive tissue in a seed, often disbudding carbohydrates, but can contain cutin Removing the secondary fower fats or proteins A waxy layer produced by the buds on each stem when they are cuticle that helps protect a leaf very small so that each stem only epidermis from dehydration and diseases produces a single large blossom The outermost layer of cells cutting discoloration epinasty A vegetative plant part, removed Abnormal color changes Drooping of leaves from the parent plant, that will distortion epiphyte produce adventitious growth to Curling, cupping, twisting, or An organism that grows on form a whole new plant thickening of leaves or other another organism but is not cutting back plant parts parasitic Process of removing spent ethylene blooms, stems, and some foliage Plant hormone, found only in to encourage a second bloom or a gaseous form, that induces stimulate the growth of foliage ripening, epinasty, abscission, and senescence 355 UW-Extension Master Gardener Manual: Foundations in Horticulture

etiolation gall herbaceous An increase in internode length, Abnormal growth in plants in Dying down to the ground at the caused by a lack of light, that response to insect feeding or end of the growing season leads to spindly stems egg laying, mites, and some herbicide evapotranspiration pathogens Pesticide that kills or prevents the Water movement in a plant germination growth of plants from a combined efect of A complex process whereby herptiles transpiration and evaporation a seed embryo goes from a Reptiles and amphibians referred exoskeleton dormant state to an active, to collectively growing state An insect’s hard outer shell, honeydew which helps protect it from the gibberellin A sugary, sticky substance environment, and to which its Plant hormone that stimulates excreted by aphids muscles are attached cell division, elongation, and horizons break seed dormancy fertilization Layers of soil generally parallel to The union of a male sperm girdling the soil surface, whose physical nucleus from a pollen grain with Severing the vascular system characteristics difer from the a female egg of a tissue of a stem, often by layers above and beneath removing a strip of bark from a fertilization (plant nutrition) horticultural oil woody plant’s branch or trunk or Applying plant nutrients to the Mineral or vegetable oil used as by insect feeding environment around a plant pesticide gradual metamorphosis flament horticultural vinegar Insect development with three The slender, stalk-like structure Acetic acid applied as a post- life stages: egg, nymph, adult that supports the anther emergent non-selective fagellum (pl. fagella) gravitropism herbicide Plant growth in response Structures that allow some humus to gravity (previously called bacteria to move about in their Very highly decayed, stable geotropism) environment organic material found in soil guard cell fedgling hypha (pl. hyphae) Specialized epidermal cell that Young birds that are fully The threadlike elements of the opens and closes in response to feathered but not yet expert fiers mycelium environmental stimuli (water, foret light) hypocotyl An individual fower in an Part of a plant embryo or gynoecious inforescence seedling plant that is between Having only female fowers foricane the cotyledons and the radicle hardening of Cane that has lived through the imperfect fower Gradually exposing plants to winter Flower in which either stamens or outdoor conditions forking pistils are lacking hardpan Abnormal branching of a root importation A compact layer of subsoil that frass Biological control means by occurs at the depth of a tilled Insect fecal matter which foreign natural enemies layer of soil fruiting bodies are released against non-native heading-back cut Reproductive structures in pests Removing a branch section to a fungi in which spores are often incomplete fower lateral branch or bud, not all the produced Flower in which a fower part way to the base fungi (stamen, pistil, petals, or sepals) heartwood A large group of organisms is missing The non-functional xylem cells classifed in their own kingdom in the center of a woody branch fungicide or trunk Pesticide that kills fungi 356 GLOSSARY indeterminate leader midrib Growth habit in which stems See central leader The main vein of a leaf, running elongate indefnitely without leaf axil down the center of the blade being limited by a terminal The node where a petiole meets modifed degree days inforescence or other structure; a stem A measurement of degree days with inforescences in axils leaf bud that compensates for reduced (compare to determinate growth) Comprised of a short stem with growth rate at high temperatures indicator plant embryonic leaves molt Common plant with growth leaf drop Shedding of the exoskeleton events correlated with unrelated Phenomenon in which a tree monocots biological events drops the majority of its leaves A group of plants, also known as inforescence leafmining monocotyledons, whose seed A cluster of fowers Insect feeding between the has one cotyledon inorganic pesticide upper and lower leaf surface that monoecious Pesticides of elemental minerals leaves a discolored serpentine Having both male and female that contain no carbon trail or visible blotch fowers on the same plant insecticidal soap lesions mosaic Soaps used to control some Well-defned relatively small A symptom, also know as mottle, insect pests dead areas on plant tissues in which foliage has blotchy light insecticides lime sulfur and dark green coloring Pesticides that kill insects Mixture of lime and sulfur used as mottle internal dormancy a fungicide Appearance of uneven spots Physiological conditions that loam from disease or nutrient problem delay germination A soil with roughly equal multiple fruits internode proportions of sand, silt, and clay Fruits that are derived from The area between two nodes meristems a tight cluster of separate, juglone Specialized cells that are a plant’s independent fowers borne on a A chemical produced by trees in growing points—the site of rapid, single structure the walnut family that is toxic to almost continuous cell division mycelium many vegetables and ornamental mesophyll A mass of hyphae plants Specialized cells for mycorrhiza (pl. mycorrhizae) kaolin photosynthesis, found in leaves, Fungi that grow in association A type of clay applied to plants that contain chloroplasts with the roots of a plant in a to create a barrier that prevents metamorphosis symbiotic relationship insects from feeding on them A change in form; the process of necrotic lamina transformation from an immature Dead area The expanded thin structure on insect to the adult stage neem either side of the midrib of a leaf, microbe Organic pesticide derived from also known as a “blade” A single-cell living organism the neem tree (Azadirachta larva (pl. larvae) including fungi, bacteria, viruses, indica) The worm-like immature stage of and phytoplasmas nematicide insects that undergo complete microclimate Pesticide that kills nematodes metamorphosis Small area within a landscape nematode lateral root with diferent conditions than the Tiny unsegmented round worm Side or branch root that arises surrounding area nestling from another root micronutrient Very young bird that lacks leaching Element essential for plant feathers and is covered with The process of chemicals and growth that is only needed in down minerals being transported by very small (micro) amounts water down through the soil 357 UW-Extension Master Gardener Manual: Foundations in Horticulture

net-veined parallel-veined photosynthate Veins that branch from the main Numerous veins running Product of photosynthesis: rib or ribs and subdivide into essentially parallel to each other sugars, carbohydrates fner veinlets and connected laterally by photosynthesis node minute, straight veinlets Process by which leaves absorb An area on a stem where buds parasitoid sunlight and turn carbon dioxide are located Natural enemy that develops into sugars nontunicate within a pest’s body and phototropism Bulbs, such as lilies, with kills it when the immature’s Bending of a plant towards a individual scaly modifed leaves development is complete light source not protected by a papery pathogen phylum (pl. phyla) covering Disease-causing organism that A taxonomic rank used in the nymph may debilitate or kill an organism classifcation of organisms Immature stage of insects that perennial physical barrier undergo gradual metamorphosis A plant that lives for more than Barrier that prevent pests from ofset two years getting to a plant Small, virtually complete plant perfect fower phytoplasma that develops naturally and A fower that contains both Bacteria-like organism that asexually at the base of the main functional stamens and pistils lacks a true cell wall and causes stem on a parent plant from pest control diseases such as “yellows” lateral shoots The traditional, reactive strategy phytotoxic opposite leaves for dealing with pest problems Toxic to plants Positioned across the stem from pest management pinching back each other, with two leaves at Proactive response to pest issues Pruning back the growing stems each node that involves planning response of certain plants to encourage order strategies before problems occur the plant to branch A taxonomic rank used in the pesticide pinnate classifcation of organisms Any substance used to directly Veins that extend laterally from organic pesticide kill pests or reduce or prevent the the midrib to the edge A pesticide derived from a damage they cause pistil natural source petiole A fower’s female part, generally organs Stem-like appendage that holds a shaped like a bowling pin and In plants, external structures such leaf away from its stem located in the center of a fower as leaves, stems, roots, fowers, phloem pistillate fower fruits, and growing points The part of a plant’s vascular Female fower with a functional ovary system that carries food such as pistil or pistils but no stamens The enlarged lower part of the sugars pith pistil phosphorus The center of a stem that lends oxidation Essential plant nutrient involved strength and structure A biochemical reaction involving in the formation of oils, sugars, plant nutrition oxygen and starches as well as fowering A plant’s need for and use of and root formation palmate basic chemical elements Having a shape similar to that of photoperiod pollen a hand with the fngers extended, The amount of time a plant is The fne powderlike material with three or more veins, leafets, exposed to light produced in the anther (or male or lobes radiating from the base photoperiodism cone); each microscopic grain of the leaf blade Physiological reaction of contains a male sex cell organisms to the length of day or night 358 GLOSSARY pollination pupa (pl. pupae) rodenticide The transfer of pollen from an Non-mobile stage of insects Pesticide that kills rats, mice, anther to a stigma either by wind that undergo complete ground squirrels, and other or pollinators metamorphosis during which rodents pollinator larval structures disintegrate and root girdling The agent of pollen transfer, reconstruct into a very diferent Roots that grow around and frequently insects looking adult constrict other roots and the pollinizer pustule trunk A plant that is the source of A type of fungal fruiting body root fare pollen transferred by a pollinator such as in rusts The portion at the bottom of a for cross-fertilization pyrethrum tree trunk where the trunk fares, pome Natural insecticide that serves as or widens, and which should Fruit that has a feshy exterior a nerve toxin derived from a type generally be visible after planting surrounding a reproductive of chrysanthemum rootstock chamber quiescent The belowground portion of potassium An inactive stage of seed or fruit or other grafted trees (see Essential plant nutrient that is insect development that allows understock); usually genetically involved in building proteins them to survive for a long time distinct from the scions (the aboveground portion) to which predator racemose they are grafted An organism that preys upon Inforescence that begins to other organisms bloom from the bottom forets rosulate leaves and progresses to the top Arranged in a rosette around a primary nutrients stem with extremely short nodes The primary plant nutrients radicle are nitrogen, phosphorus, and The part of a plant embryo that rot potassium develops into a root Disease typically caused by fungi or bacteria that can lead to the primary root reddening wholesale destruction of plant Root that originates at the lower Common discoloration symptom, tissue in any plant part end of a seedling’s embryo; also also known as marooning called “radicle” relative humidity runner Specialized stem that originates primocane Ratio of water vapor in the air to in the leaf axil at the crown of the Cane that appears during the the amount of water the air can plant and grows along the soil growing year hold at the current temperature and pressure surface to produce a new plant primordium (pl. primordia) at a node A very small preformed fower respiration saprophyte in a dormant bulb that will Chemical reaction with oxygen Fungi that derive nutrients eventually mature and bloom by which sugars and starches are converted into energy by feeding on dead organic provenance materials The geographic area of a rhizome sapwood particular segment of a species Belowground stems that grow Older xylem cells in trees that with a very large natural range horizontally. New growth emerges at points along the stem still function as storage for pubescence to form new plants photosynthates Hairs on leaves that are scafold extensions of epidermal cells and ricey curds Major lateral branch of a tree make leaves feel like velvet Abnormal plant development in caulifower that results when the scale plants are exposed to excessive Insects of various sizes and heat shapes that look like hard-shelled ringspot or cottony bumps on twigs; also Concentric ring pattern on leaves a type of leaf on some conifers or fruits caused by viral infections or bulbs 359 UW-Extension Master Gardener Manual: Foundations in Horticulture

scarifcation snag stolon A process of softening or nicking Standing dead tree used by A prostrate stem, at or just below a seed coat to break seed wildlife for cover and shelter the surface of the ground, that dormancy soil test produces roots at its nodes scion A rapid chemical analysis to stomata (sing. stoma) Selected cultivar grafted to determine relative nutrient Tiny openings, also known as rootstock availability to plants stomates, that allow water, secondary nutrients solitary fower oxygen, and carbon dioxide to Calcium, magnesium, and sulfur When a plant produces one pass in and out of leaves seed bank fower per stem stratifcation The accumulated viable weed species name Process to break plant or seed seeds in soil A two-word name based on a dormancy involving a period of cooling seed coat precise system of classifcation A hard outer covering that that is unique to every organism stunting protects a seed from disease and spinosad Abnormal slowing or stoppage insects and may cause dormancy Biological insecticide derived of growth or development so the plant does not achieve its senescence from a soil microorganism expected size Maturation and mortality of plant spiracle parts Opening in an insect’s style The part of a fower’s pistil that sepals exoskeleton through which connects the ovary and stigma The outermost whorl of parts oxygen is delivered to trachea, that form a fower, collectively then tracheoles, and fnally cells stylet called the calyx spore Hollow mouthpart of plant parasitic nematodes, used septa (sing. septum) Seed-like structure in fungi used to puncture cells and obtain Partitions that divide tube-like for reproduction nutrition hyphae into individual cells spot sucker sessile Well-defned relatively small A rapidly growing shoot arising Stalkless, a leaf blade with no area on plants that is a common from the roots or rootstock petiole symptom of fungal and bacterial pathogens, also known as “lesion” sunscald sexual reproduction Damage to plant tissues from Recombination of genetic spur overexposure to the sun material to form a genetically Short, stubby side stem that unique individual arises from a main stem on symbiotic relationship woody plants Any of several living shearing arrangements between diferent Process of removing new growth, stamen species, with both positive and generally on evergreen shrubs A plant’s male reproductive organ, consisting of an anther negative associations included skeletonizing and a flament synthetic pesticides Insect feeding in which the leaf Pesticides manufactured from blade is consumed, leaving leaf staminate fower chemicals veins intact Male fower that contains stamens but no pistils tadpole simple fruit Amphibian larvae, which may or Fruit that develops from a single stigma may not look much like the adult fower and a single ovary Top portion of the pistil, connected by the style to the thatch simple leaves ovary A loose, intermingled organic Leaf blades that are a single, layer of dead and living shoots, continuous unit, not divided into stippling stems, and roots that develops parts (compare to compound Stippled appearance of leaves between the zone of green leaf) caused by insects that rasp of or puncture plant tissues and feed vegetation and the soil surface on the juices that are released 360 GLOSSARY thinning cut tuberous root viability Removing a branch to its point of Underground storage organ A seed’s ability to germinate origin (compare to heading cut) made of root tissue vine thorax tuber A plant with a long, trailing stem One of three main insects parts Modifed underground stem that virescence where the legs and wings attach stores food for a plant Phenomenon in which normally tilth tunicate colored plant parts—such as State of aggregation of soil in Bulbs, such as tulips and onions, fowers—turn green relation to suitability for plant that have concentric scales wart growth (modifed leaves) and are covered Bump-like growth on fruits in a papery sheath tipping water sprout Removing the top ¼ of a cane turgor pressure a rapidly growing shoot, usually topdressing The fullness and frmness of plant unbranched, growing on the Spreading a thin layer of tissue needed to maintain cell trunk or scafold limbs shape and ensure cell growth compost over a lawn or garden whorled leaves area to enhance the soil and understock Three or more leaves attached at add nutrients in a slow-release Lower portion of a grafted tree a single node, arranged in circles manner that provides the new plant’s root around a stem system, also known as rootstock topping wilting Removal of whole tops of variety Leaves or entire plants that trees, an inappropriate pruning A plant with one or more clearly become limp from a lack of water method that may result in distinguishable characteristics xeric increased structural problems that occurs in natural populations Adapted to drought torpor vascular system xylem A period in which some insect Water-conducting tissue, The part of a plant’s vascular species go without food and slow consisting of xylem, phloem, and system that conducts water and their metabolism down vascular cambium, continuous dissolved minerals totipotent throughout a plant yellowing A plant part’s ability to develop vascular wilt Discoloration also known as into a complete plant Pathogens that invade a plant’s chlorosis training vascular system and cause wilt The use of pruning, trellising, and symptoms staking, etc. to manipulate the vector growth and shape of a plant Organism capable of transmitting transpiration plant pathogens Process by which water is lost vegetative phase through the leaves of the plants The non-reproductive “body” of trap fungi Tool used to detect or remove vegetative reproduction specifc pests Propagating plants from stems, trellising leaves, or roots, resulting in a new Placing branches on a trellis or plant that is genetically identical other structure to hold them in to the parent certain positions venation true bulb The way in which veins are Underground stem surrounded distributed in a leaf blade by modifed leaves vermicompost true leaves Compost resulting from red First leaves to form on a seedling worms after the cotyledon(s) emerge 361

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