Plant Science Terms - I

Imbibition - portion of the germination process that involves the absorption of water, causing the seed to swell, and that triggers cell enzyme activity, growth, and the bursting of the seed coat

Imbricate - type of true bulb that does not have the tunic (papery covering) to protect the fleshy scales; a flower bud in petals and sepals overlap each other

Immobilization - process by which soil microorganisms use available nitrogen as they break down materials with a high C:N ratio, thus reducing the amount of nitrogen available to plants

Immune - plant that does not become diseased by a specific pathogen. (See also Resistance, Tolerant)

Imperfect flower - flowers lacking either the stamen or the pistil

Incised - margin cut nearly to the midrib into sharp, deep, irregular incisions

Included bark - "Ingrown" bark tissues which often develop where two or more stems grow closely together, causing weak, under-supported branch angles

Incompatible - kinds or varieties of a species that do not successfully cross pollinate or intergraft

Incomplete fertilizer - fertilizer missing one or two of the macronutrients, such as 0-20-0

Incomplete flower - structurally, flowers consist of four main parts: sepals, petals, stamens, and pistils

Incomplete metamorphosis - see Simple metamorphosis

Incubation - period of development during which a pathogen changes to a form that can penetrate or infect a new host plant

Indehiscent - type of dry fruit in which the fruit wall does not split at any certain point or seam at maturity. Indeterminate growth. Growth that is potentially limitless

Indeterminate - plant growth habit in which stems keep growing in length indefinitely. For example, indeterminate tomatoes are tall, late-fruiting, and require staking for improved yield. (See also Determinate)

Indeterminate inflorescence - raceme, panicle, spike, catkin, corymb, umbel, spadix, or head. In a raceme, a flower develops at the upper angle (axil) between the stem and branch of each leaf along a long, unbranched axis. Each flower is borne on a short stalk, called a pedicel

Indigenous - see Native plant

Infection - condition reached when a pathogen has invaded plant tissue and established a parasitic relationship between itself and its host

Infiltration - movement of water into soil

Inflorescence - flowering portion of a plant. The arrangement of flowers on an axis or stem and can also be a flower cluster

Inflorescence collective - group of individual flowers. The grouping can take many forms, such as a spike (flowers closely packed along a vertical stem, e.g., snapdragons), an umbel or corymb (flowers forming a flattened dome, e.g., yarrow), a panicle (a complex hierarchical arrangement of flowers, e.g., hydrangeas), or a capitulum (tightly packed disc flowers, e.g., the center of a daisy)

Inoculation - introduction of a pathogen to a host plant’s tissue

Inoculum - any part of the pathogen that can cause infection

Inorganic - being or composed of matter other than plant or animal

Insectary plant - plant that attracts beneficial insects

Insecticidal soap - specially formulated soap that is only minimally damaging to plants, but kills insects. Usually works by causing an insect’s outer shell to crack, resulting in its interior organs drying out

Insecticide - chemical used to control, repel, suppress, or kill insects

Insectivore - animal or plant that feeds mainly on insects. Any of various small, usually nocturnal mammals of the order Insectivora that feed on insects and other invertebrates

Instar - stage of an insect’s life between molts

Integrated control - approach that attempts to use several or all available methods for control of a pest or disease

Integrated insect control - use of a variety of insect control methods, beginning with simpler

Integrated pest management - method of managing pests that combines cultural, biological, mechanical, and chemical controls, while taking into account the impact of control methods on the environment

Intensive gardening - practice of maximizing use of garden space, for example, by using trellises, intercropping, succession planting, and raised beds

Intercalary meristem - found mostly in monocots, these cells divide and provide the growth of the leaf from the base of the plant

Intercropping/Interplanting - practice of mixing plants to break up pure stands of a single crop.

Interiorscape - interior planting, usually referring to professional designs installed in commercial buildings

Internode - area of the stem that is between the nodes and also has no buds

Interstem/interstock - intermediate stem piece of a graft combination made up of more than two parts, i.e., the piece between the scion and the rootstock. Often has a dwarfing effect

Invasive - growing vigorously and outcompeting other plants in the same area; difficult to control

Ion - electrically charged particle. In soils, an ion refers to an electrically charged element or combination of elements resulting from the breaking up of an electrolyte in solution

Isolation - separation of a pathogen from its host by culturing on a nutrient medium or on an indicator plant

Isoptera - major order of insects that have two pairs of wings, or are wingless, and chewing mouthparts (termites)


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