O: Symbol for oxygen, an essential element.
O'Keeffe: Optimara variety belonging to the Artist's Palette series. Named for the American painter, Georgia O'Keeffe. Standard African Violet (4-inch pot size) with single, bi-color flowers. Flowers are white with a purple edge. Leaves are medium green. Introduced 1995. (AVSA Reg. No. 8332) More information.
Oak Leaf: Leaf type. Describes an African Violet leaf which has slight indentations around the edge. A leaf with more pronounced indentations is either ruffled or serrated.
Odessa: Optimara variety. Medium, standard African Violet (4-inch pot size) with single, pink flowers. More information.
Offset: See Sucker.
Ohio: Optimara variety. Medium, standard African Violet (4-inch pot size) with semi-double, red flowers and dark green leaves (red reverse). Introduced 1987. (AVSA Reg. No. 6587) More information.
Oidium: The fungus which causes Powdery Mildew.
Oklahoma: Optimara variety. Medium, standard African Violet (4-inch pot size) with frilled, dark pink flowers and dark green leaves. Introduced 1988. (AVSA Reg. No. 6967) More information.
Omaha: Optimara miniature variety. See Little Omaha Girl.
Omita: Optimara variety. Medium, standard African Violet (4-inch pot size) with single, burgundy flowers and medium green leaves. Introduced 1999. More information.
Ontario: Optimara variety. Medium, standard African Violet (4-inch pot size) with single, white flowers and medium green leaves. Introduced 1987. Improved 1996. (AVSA Reg. No. 6588) More information.
Opal: Optimara super miniature variety. See Little Opal.
Open Pollination: Also called natural pollination. Refers to pollination that occurs naturally, i.e., without human interference. Contrast with Cross-Pollination.
Ophelia: Rhapsodie variety. Standard African Violet (4-inch pot size). Introduced 1972. More information.
Optimara: Popular trademark for African Violets. Introduced in 1977 by Holtkamp Greenhouses. The name, Optimara, is derived from two words: optimum, meaning the best, and Usambara, the mountains in East Africa, now Tanzania, where the first recorded African Violet was discovered. The Optimara trademark includes several hundred varieties and a number of series, including the super miniature Little Jewel series, the miniature Little Indian series, the compact Little Dancer series, the Artist's Palette series, the Victorian Charm series and the extra large World Traveler series. In addition, Optimara has a line of plant care products developed especially for African Violets. The Optimara plant care line includes fertilizers, potting soil and self-watering devices, such as the Watermaid, MaxiWell, MiniWell and WaterShip. Also see Rhapsodie.
Orbicularis: See Saintpaulia orbicularis.
Oregon: Optimara variety. Medium, standard African Violet (4-inch pot size) with frilled, two-tone pink flowers and medium green leaves. Introduced 1987. (AVSA Reg. No. 6589) More information.
Organic: In chemical terms, describes any compound containing carbon. More generally, the term, organic, is used to describe any substance which not produced synthetically.
Organic Fertilizer: See Natural Organic Fertilizer.
Organic Insecticide: See Organic Pesticide.
Organic Pesticide: Pesticide in which the active ingredient is not synthesized, but is a naturally-occurring compound derived from plant or animal sources. Contrast with Elemental Pesticides and Synthetic Pesticides. See Neem and Pyrethrin. Also see Botanical Pesticide.
Orlando: Optimara variety. Small, standard African Violet (4-inch pot size) with frilled, dark blue flowers and medium green, girl-type leaves. Introduced 1987. (AVSA Reg. No. 6590) More information.
Ornamental: Describes any plant cultivated for decorative purposes. Plants classified as ornamental are generally contrasted with those grown as food sources, though there are other, non-ornamental uses for plants. Ornamentals include flowers such as African Violets.
Orthene: Popular trademark for an insecticide containing Acephate.
Orthocide: Popular trademark for a fungicide containing Captan.
Osmocote: Popular trademark for a slow-release fertilizer. This and other slow-release fertilizers are not recommended for African Violets. While these types of fertilizers are designed to reduce the frequency of application, they make it easy to overfertilize, especially for those who do not have a lot of experience with them. In addition, because the release of nutrients is influenced by various environmental factors, the results can sometimes be unpredictable.
Omaha: Optimara miniature variety. See Little Ottawa Girl.
Ovary: On a bloom, the part of the pistil which contains the ovules.
Ovate: Leaf type. Describes an African Violet leaf which is ovate or oval-shaped. While sometimes called spooned, an ovate leaf does not necessarily have the concave feature associated with that leaf type.
Overpotting: Cultural problem which describes an African Violet being grown in a pot that is too large. When overpotted, an African Violet will expend the greatest part of its energy growing roots, thus reducing the amount of energy which might otherwise go to growing leaves and flowers. In addition, because the larger pot size will hold more water than an African Violet can absorb, conditions of excessive moisture will leave the African Violet susceptible to potentially fatal diseases, such as Crown Rot, Pythium and Root Rot. More information.
Overwatering: Cultural problem which describes an African Violet that is receiving too much water. The soil in which African Violets are potted should be consistently moist, but never soggy. Excessive moisture creates an environment favorable to such diseases as Crown Rot, Pythium and Root Rot. Overwatering can also cause a condition known as denitrification. More information.
Ovule: On a bloom, the part of the ovary which, when pollinated, will develop into a seed. Also see Pollination.
Oxygen: (O) Major element essential to the growth and vitality of African Violets. Sometimes called a free element. Oxygen is absorbed from the air and water, primarily in the form of either carbon dioxide or H2O. Through the process of photosynthesis, oxygen combines with carbon and hydrogen to form plant carbohydrates.
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