Plant Glossary of



Plant Glossary H

Habituated: A state wherein a culture no longer responds to a substance, such as a hormone or a nutrient, because the culture no longer requires that hormone or nutrient or is no longer able to utilize it

Haploid: The number of chromosomes (n) in reproductive or germ cells, which is half the normal number of chromosomes (2n) in vegetative cells

Hardening Off: The process of gradually acclimating plants to tougher environmental conditions, most notably the less humid conditions of the field or greenhouse that is experienced in cultivation

Hardwood Cutting: A cutting taken from a stem when the bark is mature and the wood is fully hardened for the winter

Head Back: To cut back the main branches of a tree or shrub by at least one half of their length

HEPA: High efficiency particulate Air filters, an essential component of laminar air flow hoods to help ensure sterile transfer work (plant propagation from test tubes)

Herbaceous Plant: A plant with soft, nonwoody stems. In cold climates, the topgrowth of herbaceous plants usually dies back in winter

Heterotrophic: Requiring external organic substances as sources of food and nutrients

Hood: See Transfer Chamber

Hormone: Any naturally occuring or synthetic chemical, such as cytokinins and auxins, that affects growth and development. See also Growth Regulator

Hot Plate, Stirrer: An electrical device that serves as both a hot plate and a magnetic stirrer, the heating and stirring features can be used simultaneously or independently of one another

Humic Acid: See Wikipedias entry on this: Humic Acid See also: Fulvic Acid for more major plant useage.

Humidity: The amount of moisture in the air

Humus: The organic component of soil, formed by the decomposition of leaves and other plant material by soil microorganisms.

Hybrid: The offspring of genetically different parents, usually of distinct (interspecific hybrid) F1 hybrids are uniform, vigorous offspring, resulting from crossing two genetically pure parents. In Artificial reproduction, by protoplast fusion and other methods of gene transfer in genetic engineering

Hydrate: A compound with chemically bound water See also Water of hydration

Hypocotyl: The portion of a seedling stem below the cotyledons and above the roots

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