Tree work words: propagation, grafting and seed sources

Nurseries, seed collectors and fruit growers use a set of words that tree crews seldom meet on a job. This page lists what three named sources say those words mean. One is the glossary of the USDA Forest Service Woody Plant Seed Manual, Agriculture Handbook 727, dated July 2008. The other two are grafting publications from University of Missouri Extension and Mississippi State University Extension. A word none of them defines is left out.

Each meaning is written in our own words from the page named under it. Other word lists are on tree work words: pruning, planting and soil and tree work words: biology and plant health, and the full list is the tree work glossary.

Grafting and budding words

Term	Meaning and source
Grafting	Mississippi State describes it as joining parts of two plants so they heal and grow as one, and calls it a method of asexual propagation. Missouri adds that the upper part, the scion, becomes the top of the plant and the lower part becomes the root system or part of the trunk. Source: Mississippi State University Extension, Basic Grafting Techniques (P3402); University of Missouri Extension, Grafting (G6971)
Scion	Missouri defines it as a piece of detached twig or shoot, usually with two or three buds. Mississippi State describes it as the stem or other above-ground part of the wanted variety, a shoot with several dormant buds that make the new stem and branches. Source: University of Missouri Extension, Grafting (G6971); Mississippi State University Extension, Basic Grafting Techniques (P3402)
Rootstock, stock, understock	The part of a graft that becomes the root system of the grafted plant. Missouri gives stock and understock as other names for it. Source: University of Missouri Extension, Grafting (G6971); Mississippi State University Extension, Basic Grafting Techniques (P3402)
Interstock, interstem	Missouri defines it as a piece of plant grafted between the scion and the understock, usually forming the trunk or a part of it. Source: University of Missouri Extension, Grafting (G6971)
Cambium	Missouri defines it as a single layer of cells between the wood and the bark that makes new cells, and says the scion's cambium must line up with the stock's for a good union. Mississippi State places the cambium region between the xylem and phloem. Source: University of Missouri Extension, Grafting (G6971); Mississippi State University Extension, Basic Grafting Techniques (P3402)
Budding	Mississippi State says budding is done by inserting one mature bud of the wanted cultivar into the rootstock, touching the cambium, and says it is usually done late in the growing season. Missouri says that when the scion is only a single bud, the form of grafting is called budding. Source: Mississippi State University Extension, Basic Grafting Techniques (P3402); University of Missouri Extension, Grafting (G6971)
Cultivar	Missouri says the term is used in place of variety, and that it means cultivated variety, set apart from a botanical or natural variety. Source: University of Missouri Extension, Grafting (G6971)
Top-working	Missouri uses it for changing a large tree from an old variety to a new one by grafting. Mississippi State describes an older orchard being top-worked with a newer variety, so the established root system is kept. Source: University of Missouri Extension, Grafting (G6971); Mississippi State University Extension, Basic Grafting Techniques (P3402)
Inarching, approach grafting, bridge grafting	Mississippi State lists these names for the repair of a large tree or specimen plant damaged at or just above the soil line by equipment, disease, rodents, storms or vandalism. Source: Mississippi State University Extension, Basic Grafting Techniques (P3402)
Graft union	Missouri says a good union depends on compatible stock and scion, and that plants closely related botanically form a good one. It says a poor union gives plants that grow poorly, break off or die. Source: University of Missouri Extension, Grafting (G6971)
Chimera	Missouri says a different type of shoot sometimes appearing at a graft union is the result of a chimera, a type of mutation, and not a true mixing of the genes of the two plants. Source: University of Missouri Extension, Grafting (G6971)

Cloning and cutting words

Term	Meaning and source
Asexual reproduction	The Forest Service manual defines it as reproduction without fertilization, done in woody plants usually by rooting stem cuttings, air-layering, grafting or budding. Source: USDA Forest Service, Woody Plant Seed Manual, glossary
Propagule	Any plant part, such as a bud, tuber, root, shoot or spore, that can be used to propagate a new plant. Source: USDA Forest Service, Woody Plant Seed Manual, glossary
Clone	The manual's first meaning is a group of genetically identical plants made by vegetatively propagating one plant. Its second meaning is a cell line from a single cell. Source: USDA Forest Service, Woody Plant Seed Manual, glossary
Ortet	The original plant from which a vegetatively propagated clone came. Source: USDA Forest Service, Woody Plant Seed Manual, glossary
Ramet	One member of a clone, vegetatively propagated from the ortet. Source: USDA Forest Service, Woody Plant Seed Manual, glossary
Hardwood cutting	The manual's term for a cutting taken in the dormant period from the growth made in the season just ended. Source: USDA Forest Service, Woody Plant Seed Manual, glossary
Softwood cutting	A cutting taken from soft, succulent new shoots that have just begun to harden. The manual says this is normally in spring, and at any time of year in plants with several flushes of shoot growth. Source: USDA Forest Service, Woody Plant Seed Manual, glossary

Seed treatment words

Term	Meaning and source
Dormancy	A physiological state in which a seed that is ready to germinate does not, even in favourable conditions. The manual says the word also covers comparable conditions in the growth of all plant parts. Source: USDA Forest Service, Woody Plant Seed Manual, glossary
After-ripening	Biochemical or physical processes in seeds, bulbs, tubers and fruit after harvest, often needed before germination or renewed growth. Source: USDA Forest Service, Woody Plant Seed Manual, glossary
Stratification	A pre-germination treatment to overcome dormancy and give rapid, even germination, made by keeping seeds in cold, moist conditions for a set time. The manual says it is sometimes preceded by moisture at room temperature. Source: USDA Forest Service, Woody Plant Seed Manual, glossary
Prechilling	Exposing soaked seeds to cool temperatures of 5 to 10 degrees Celsius for a few days before germination. The manual says it is the same as stratification, but prechilling is the word more used in seed testing and stratification the word more used in nurseries. Source: USDA Forest Service, Woody Plant Seed Manual, glossary
Scarification	Breaking the seedcoat before germination, usually by abrasion or a brief strong acid treatment, so water and gases pass more easily or the coat resists less. Source: USDA Forest Service, Woody Plant Seed Manual, glossary
Germinative capacity	The share of seeds that germinate normally in a period when germination is practically complete, usually given as a percentage. The manual lists germination percentage as a synonym. Source: USDA Forest Service, Woody Plant Seed Manual, glossary

Seed source and seed quality words

Term	Meaning and source
Provenance	The original geographic source of seed. The manual defines seed source separately, as the place where a seedlot was collected. Source: USDA Forest Service, Woody Plant Seed Manual, glossary
Seed zone	A marked area with set boundaries and height limits, inside which soil and climate are even enough that the genetic make-up of the plants is likely to stay fairly uniform, as shown by progeny tests of seed sources. Source: USDA Forest Service, Woody Plant Seed Manual, glossary
Planting zone	An area of reasonably even growing conditions in which plants from one or more seed sources are well adapted. Source: USDA Forest Service, Woody Plant Seed Manual, glossary
Seedlot	A set quantity of seeds of fairly uniform quality, which may come from one place or one seed collection zone, all collected in the same year. Source: USDA Forest Service, Woody Plant Seed Manual, glossary
Race, ecotype	A population inside a species whose general traits are distinct from other populations. The manual gives ecotype as the synonym. Source: USDA Forest Service, Woody Plant Seed Manual, glossary
Cline	A steady gradient of traits or genes across a species range, usually tied to a gradient in some environmental factor. Source: USDA Forest Service, Woody Plant Seed Manual, glossary
Seed orchard	A plantation of clones or seedlings from selected trees, grown for early and plentiful seed and for balanced, random mating. Source: USDA Forest Service, Woody Plant Seed Manual, glossary
Seed-production area	An existing stand that has been thinned of poor trees and managed for early and plentiful seed. Source: USDA Forest Service, Woody Plant Seed Manual, glossary
Source-identified seed	A seedlot that a designated authority says comes from a defined seed source. Source: USDA Forest Service, Woody Plant Seed Manual, glossary
Selected seed	A seedlot from carefully chosen natural stands or plantations that meet set standards and are approved and registered by a designated authority. Source: USDA Forest Service, Woody Plant Seed Manual, glossary
Certified seed	A seedlot that a designated certifying agency attests comes from trees of known identity, produced so that the identity is assured. Source: USDA Forest Service, Woody Plant Seed Manual, glossary
Seed certification	A guarantee of seed identity and quality by a recognized agency, usually shown by a certificate. The manual lists category, species and variety, year of collection, origin, purity, soundness and germinative capacity as the details. Source: USDA Forest Service, Woody Plant Seed Manual, glossary

Reading these sources

The seed manual is a federal handbook for foresters and seed workers, so its terms are written for trees and shrubs grown from seed. The two extension publications are written for fruit trees and nursery plants, and Missouri's page was reviewed in August 2022. None of the three is a regulator. The manual's certified, selected and source-identified seed are its own category names, and a seed certification scheme in a given state or country has its own written rules.