The Bonsai Glossary is a helpful tool for bonsai enthusiasts at every level, as much of the information on bonsai gardening assumes a basic understanding of tree and plant terminology. While it doesn’t cover all of the Japanese terms used in bonsai gardening, it attempts to define all the terms in “plain English.” It’s worth noting that some of the definitions may still be cryptic because they rely on other terms that may not be familiar to you.

A

Accent Plant: A small plant displayed next to a bonsai, typically used when a bonsai is being formally displayed at a show or exhibition. Accent Plants can include any perennial, bamboo or grass.

Air Layering: A method of propagating bonsai that is more complicated than taking cuttings, but has the advantage that the propagated portion can continue to receive water and nutrients from the parent plant while it is forming roots. This is important for plants that form roots slowly, or for propagating large pieces.

Akadama: A classic Japanese Bonsai soil meaning red clay balls, imported from Japan. This volcanic soil has been used for thousands of years by bonsai artists on most types of deciduous bonsai trees.

Apex: The highest point of the tree, which on a bonsai can be a single branch or a series of small branches. It can also be foliage or jin.

B

Back budding: The process of encouraging new growth on a branch where growth is currently non-existent. Back budding occurs when new buds appear on “old” wood.

Bleeding: The loss of sap caused by wounding or pruning.

Bonsai: The Japanese term for the art of cultivating and training a plant to create the illusion of a dwarfed tree. Bonsai is a Japanese word made up of two characters or word phrases, “bon” and “sai”. Bon is pronounced as the English word “bone”, and means pot, container or tray. Sai is pronounced as the English word “sigh” and means tree or plant in Japanese.

Branch bender: A clamp or jack used to bend branches or trunk into a different position.

Branch splitter: A cutting tool specially designed to split trunks with minimal residual damage, also known as a trunk splitter.

Buttress: The area of a tree trunk where the roots meet the soil surface, also known as root-flare. It is usually styled to convey strength.

C

Chlorosis: refers to the yellowing of leaf tissue caused by a lack of chlorophyll, with possible causes including poor drainage, damaged roots, compacted roots, high alkalinity, and nutrient deficiencies in the plant.

Callus: a type of woody ‘scar’ tissue that forms over a wound where a branch has been pruned, as part of the tree’s healing process.

Cambium: the layer of living tissue, typically green, located between the sapwood and the bark. In regions with alternating seasons, the annual rings produced by the cambium can be discerned due to the contrast between the large wood elements produced in the spring and the smaller ones produced in the summer, which can be used to determine the age of a tree.

Concave cutters: are bonsai tools used for removing branches with a flush or slightly depressed cut. They are considered to be one of the most important bonsai tools and are also known as Mataeda Hasanmi. Specifically designed to cut branches flush to the trunk, this type of cut allows the wound to heal quickly and smoothly, without creating an unsightly bump on the trunk of the bonsai tree. They are necessary for styling bonsai and pre-bonsai nursery stock.

Canopy: refers to the peripheral foliage of the upper branches and those on the outer part of the tree.

Crown: the upper part of a tree where branches spread out from the trunk and define the bonsai silhouette.

Conifer: a type of tree that bears cones, mainly evergreen trees such as pines, cedars, spruces, and junipers. Coniferous trees have small and waxy leaves, sometimes needles, which are usually kept all year.

Cut Paste: is a type of wound sealant specially made to promote healing and prevent sap from bleeding. It is very popular among experienced bonsai enthusiasts.

D

Deciduous: Refers to trees that have a seasonal growth cycle where new foliage is produced in the spring, grows throughout the summer, turns colors in autumn, and drops in the winter, leaving buds on the branches for next spring’s new foliage. Deciduous trees enter a state of dormancy annually.

Dieback: The death of shoots or branch tips caused by drought, insects, disease, lack of light, or extreme weather conditions.

Defoliation: The process of leaf pruning, whereby some or all of the leaves are removed to encourage new shoots and smaller leaves which can greatly increase ramification.

Dormancy: Refers to the resting period for bonsai, where little or no growth is produced, usually during the autumn and winter months.

Dwarf: A variety or cultivar that is smaller than the species tree but retains all of the characteristics of a full-size species tree. Dwarfs are typically compact and slow-growing.

E

Evergreen: Refers to trees that normally retain most of their foliage (needles) through the winter. Pine and juniper are examples.

F

Feeder root: Fine roots that absorb water and nutrients from the soil.

Feng Shui: Translates literally to “wind-water.” Feng Shui is the ancient Chinese art of placement. The goal of Feng Shui is to achieve harmony, comfort, and balance, first in one’s environment and then in one’s life.

Fertilizer: This is “food” for your bonsai, shrubs, and plants, usually comprised of NPK: Phosphorous for the roots, Nitrogen for the foliage, and Potassium for the flowers.

Foliage pad: A cloud-shaped foliage mass on a branch. Foliage pads are shaped by training the individual branches with bonsai shears and bonsai wire.

Forest Bonsai: Created from several small plants of the same variety to simulate a forest in nature.

Fungicide: A chemical compound used to prevent the growth and spread of fungus, which can cause serious damage to a bonsai.

G

Germination: The process by which a bonsai seed leaves the dormant state and starts into growth, developing roots and shoots.

Grafting: A method of propagating bonsai where the tissue of one tree is encouraged to fuse with that of another tree. The stem of one plant is fused with another so they grow together with the benefit of adding foliage where none previously existed on a bonsai.

Girth: The circumference of a Bonsai tree measured at its widest point or at just above the root base.

H

Hair Roots: Fine roots that absorb water and nutrients from the soil.

Hard pruning: The process of cutting all stems to only a few inches above the ground. This is done to renovate an overgrown shrub. Not all shrubs respond well to this treatment – it should be used only on vigorous growing shrubs.

Hardiness: The plant’s ability to survive in the extreme temperatures of a particular geographic region. Plants can be cold hardy, heat tolerant, or both. Hardy is a term used to describe trees capable of withstanding winter frost. The U.S. Department of Agriculture’s tree and plant hardiness zone map is one good guide in helping you determine a plant’s ability to withstand an average minimum temperature.

Humidity: The amount or degree of moisture in the air.

I

Ikebana: The Japanese art of flower arrangement, which follows strict rules for representing heaven, earth, and people.

Insecticide: A chemical used to kill or repel insects, including synthetic or organic compounds, botanical and mineral powders, and biodegradable chemicals such as insecticidal soaps.

Internodes: The length of stem between nodes on a plant, where leaves, buds, and other stems originate.

J

Jin: A term in Japanese bonsai culture referring to the deadwood on the ends of branches or trunk, which can be either an old branch or a protruding part of the trunk. Jins are artificially created from unwanted branches by stripping the bark and cambium to represent a dead wood.

K

Kiyonaal: A quick-drying sealant and grafting aid that contains insecticides and fungicides, forming a smooth, dark green cover that remains quite flexible. As the callus forms, the paste drops off gradually without leaving marks.

L

Lava: A soil amendment for bonsai made from crushed volcanic ash.

Layering: A propagation method in which a stem is induced to send out roots by surrounding it with soil.

Leader: The main shoot at the top of a tree.

Lime sulfur: A chemical used to preserve Jin and Shari (dead wood) on bonsai trees, which whitens the stripped branch or trunk in order to mature a Jin or Shari. It also acts like cut paste in stopping intrusion of infection to the tree and bleaches the wood, giving it a natural color.

Loam: A type of soil composed of clay, sand, and organic matter.

M

Mame: A term used in bonsai culture to refer to the size of a bonsai, which should ideally be no more than 10cm in height and can be held in the palm of a hand.

Mesophyll: The spongy inner tissue of a leaf, functionally similar to the cortex of stems and roots, where the raw materials, carbon dioxide, and water vapor are held during the process of photosynthesis.

Mycorrhiza: A white beneficial fungus that is often found in the soil around pine trees. It usually appears as small mats of white filaments, each about 1/4 inch long, helping them absorb nutrients.

N

N.P.K.: An acronym for the three major bonsai nutrients (nitrogen, phosphorus, and potassium), used to describe the amounts of each readily available.

Nebari: The exposed surface roots of a bonsai tree from which the lower trunk originates out of the soil.

Needle: A very narrow leaf, often evergreen and usually of a stiff texture, like those found on a pine tree.

Nitrogen: An essential element of bonsai nutrition and identified by the chemical symbol N, which helps to develop foliage and stem growth.

Node: The area of a bonsai (trunk or branch) where leaf buds emerge.

P

Petiole: The structure that attaches the leaf blade to the stem in a simple leaf.

Perlite: Volcanic ash that expands to form perlite when exposed to very high heat. Perlite is lightweight and is often added to potting mixes to encourage good drainage and prevent soil compaction. Its size ranges are similar to gravel, and it is also porous, which helps to maintain soil moisture.

Phloem: The layer of tree tissue just inside the bark that conducts food from the leaves to the stem and roots. See Cambium.

Phosphorous: An essential element of bonsai nutrition identified by the chemical symbol P. It encourages root development and ripening of fruit and seeds.

Photosynthesis: The process by which plants convert water and carbon dioxide into carbohydrates using sunlight as the source of energy and the aid of chlorophyll.

pH: A measure of soil acidity expressed on a scale from 0 to 14. It is a measure of the acidity or basicity (alkalinity) of a material when dissolved in water. Roughly, pH can be divided into the following ranges:

pH 0 – 2: Strongly acidic pH 3 – 5: Weakly acidic pH 6 – 8: Neutral pH 9 – 11: Weakly basic pH 12 – 14: Strongly basic

Pinching: A technique used to control and shape soft new growth of foliage by carefully pinching or pulling off small shoots with the finger and thumb in a pinching motion.

Pot: A growing container for bonsai, usually high-fired clay. The Chinese or Japanese word bon means “tray” or “shallow pot”. To fully appreciate the beauty of a bonsai, the pot you choose should complement your tree.

Potassium: The third essential element of plant nutrition identified by the chemical symbol K. It encourages strong new growth, development of flower buds, and fruit formation.

Pot-bound: Refers to the state of a container-grown plant where root growth has filled the container to the extent of eliminating all vital air spaces. When a plant gets too large for its pot, the roots circle around inside the pot and start to restrict themselves. If your plants seem to dry out more quickly than they used to but are otherwise healthy, they are probably pot-bound. There are simply too many roots in the pot, and not enough soil is left to hold and distribute water.

Pruning: The process of controlling the shape and growth rate of a bonsai by cutting back the shoots, stems, and branches.

Pumice: A light-colored volcanic rock containing abundant trapped gas bubbles formed by the explosive eruption of magma. It is often used as a bonsai soil amendment.

R

Raffia: Derived from the raffia palm, this fiber is pliable, strong, soft, and nonshrinking when wet. It’s torn into thin strips from the leaves and, after drying in the sun, takes on a yellowish-tan hue. Raffia is used to wrap branches and trunks before bending to reduce the likelihood of splitting.

Repotting: This practice involves removing a pot-grown bonsai from its container to refresh the soil and encourage renewed root growth. It’s also an ideal time to select a new or larger pot, which is crucial to the health of the bonsai.

Rootball: When removed from its pot, a bonsai displays a large mass of roots and soil known as the rootball.

Root pruning: Cutting back the roots when repotting from one pot to another encourages new root growth and promotes future growth.

Rooting hormone: This powder or liquid growth hormone is formulated to promote the development of roots on a cutting. It’s used for the propagation of cuttings and stimulates the development of adventitious roots.

S

Sphagnum moss: This type of moss is used for lining hanging baskets, as a soil amendment, or as a rooting medium in the propagation of trees by air layering.

Shari: The Japanese term for exposed deadwood on the trunk of a bonsai, as opposed to Jin, which is a deadwood branch or protrusion. Shari is the area where the bark and cambium have been removed from the trunk to suggest struggles against natural weather conditions such as wind, lightning, snow, and ice.

Shohin: Bonsai that are less than 10 inches tall.

Soil Sieve: Used to grade soils for layering and to remove fine dust that inhibits proper drainage.

Stratify: A natural process whereby seeds are exposed to low temperatures to promote germination. These conditions can also be artificially recreated using a refrigerator or freezer.

Suiban: A Japanese ceramic tray without drainage holes used to display viewing stones (see suiseki) or for rock plantings, which are usually stood in water.

Suiseki: These “viewing stones” suggest a mountain scene or landscape and are usually displayed in shallow pots or specially carved wooden stands. The art of suiseki involves the collection, preparation, and appreciation of unaltered naturally formed stones found in mountain streams, windblown deserts, ocean beaches, or anywhere that nature may have deposited or shaped them.

T

Tokonoma: A traditional display area in a Japanese house, a tokonoma is a small raised alcove where individual specimen bonsai are displayed, consisting of three elements: the bonsai tree (man), a scroll (heaven), and an accessory (earth). Bonsai are brought inside for a short period and displayed with accent plantings and calligraphy.

Transpiration: The natural process of water loss from the surfaces of leaves and plant stems.

Tufa rock: Pronounced “toofa,” tufa rock is a type of soft limestone rock that is easily carved and ideal for rock plantings. Tufa is formed when water evaporates from lime-rich waters, leaving calcite (calcium carbonate) to crystallize, often with impurities of iron oxides (rust), which give tufa its yellow and red coloration.

Tachiagari: The movement of the trunk that goes from the rootbase (nebari) up to the first branch.

V

Variegated leaf: A green leaf design that is blotched, edged, or spotted with yellow, white, or cream color.

Vermiculite: A mineral called mica that is heated and puffed up to form lightweight, sponge-like granules capable of holding both water and air. Vermiculite is useful in rooting seedlings.

W

Wound sealant: Compounds formulated to seal cuts made on branches or the trunk of bonsai to prevent the loss of moisture and promote healing.

Whitefly: A small flying sap sucker that is of the aphid family and settles on indoor plants, sometimes in large numbers. The health of the plant can be severely compromised if not treated with an appropriate spray.

Y

Yamadori: A Japanese term for a tree collected from the wild mountain, or a tree dwarfed “in the wild” by natural circumstances.

Z

Zen: From the Japanese word meaning “meditation,” Zen is the form of Buddhism which developed in Japan.

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