Plant Science Terms - O

Obtuse - ending in an obtuse angle

Ocelli - there are two types of insect eyes: simple and compound. Simple eyes (called ocelli) have one lens that perceives light intensity but does not produce an image

Offset - new shoot that forms at the base of a plant or in a leaf axil

Oil - see Horticultural oil

Olericulture - study of vegetable production

Ooze - mixture of host fluids, bacteria, yeast, and/or fungi

Open-pollinated seed - seed produced from natural, random pollination so that the resulting plants are varied

Opposite leaf arrangement - two leaves are attached at the same point (node) on the stem, but on opposite sides

Organelle - structure within a cell, such as a chloroplast, or mitochondria that performs a specific function

Organic - relating to, derived from, or involving the use of food produced with the use of feed or fertilizer of plant or animal origin without employment of synthetically formulated fertilizers, growth stimulants, antibiotics, or pesticides; being or composed of plant or animal matter; labeling term that refers to an agricultural product produced in accordance with government standards

Organic fertilizer - natural fertilizer material that has undergone little or no processing. Can include plant, animal, and/or mineral materials

Organic matter - any material rich in carbon originating from a living organism, either plant or animal, which exist in all stages of decomposition of soils

Organic pesticide - pesticides derived from plant or animal sources

Organic production - production of food using accepted naturally occurring materials

Organism - living being

Ornamental plant - plant grown for beautification, screening, accent, specimen, color, or other aesthetic reasons

Orthoptera - major order of insects that have two pairs of wings, or are wingless, and chewing mouthparts (grasshoppers, crickets, and cockroaches)

Osmosis - passage of materials through a membrane from an area of high concentration to an area of lower concentration

Outer seed coat - protective outer shell for the seed

Ovary - part of a flower (pistil) containing one or more bodies known as ovules that will develop into seeds upon fertilization. The style and stigma are the other two parts that makes up the pistil (female sexual organ)

Ovate - egg-shaped, widest below the middle, and tapering toward the apex; two to three times longer than wide

Over-wintering - this is a process where a plant that is not cold hardy is taken indoors or otherwise manipulated to keep it alive through the winter

Ovipositor - egg ­laying organ

Ovule - within the ovary, a tissue/structure that will develop into a seed after fertilization

Oxidative respiration - chemical process by which sugars and starches are converted to energy. In plants, known as respiration


Back to Plant Science