Optimara Violet Glossary: D

d-Limonene: One of the active compounds in citrus oils, extracts of citrus peels known to have natural insecticidal properties. Also see Linalool.

Da Vinci: Optimara variety belonging to the Artist's Palette series. Named for the Italian renaissance painter and sculptor, Leonardo da Vinci. Large, standard African Violet (4-inch pot size) with single, bi-color flowers. Flowers are red and white. Leaves are medium green. Introduced 1995. (AVSA Reg. No. 8319) More information.

Daisy: Holtkamp variety (Europe). Large, standard African Violet (4-inch pot size) with single, pink flowers and dark green leaves (red reverse). Available in the U.S. as Carolyn.

Dali: Optimara variety belonging to the Artist's Palette series. Named for the Spanish surrealist painter, Salvador Dali. Small, standard African Violet (4-inch pot size) with single, bi-color flowers. Flowers are purple and white. Leaves are medium green. Introduced 1996. Improved 1998. More information.

Dallas: Optimara variety. Small, standard African Violet (4-inch pot size) with frilled, pink flowers and light green, girl-type leaves. Introduced 1988. (AVSA Reg. No. 6944) More information.

Damping Off: Sometimes called Seedling Disease. A condition which attacks the seedlings or plantlets of African Violets. Damping Off is spread by fungi such as Pythium and Phytophthora. The condition causes plantlets to wilt and collapse. More information.

Dany: Holtkamp variety (Europe). Large, standard African Violet (4-inch pot size) with single, burgundy flowers and medium green leaves. Available in the U.S. as Pamela.

Deadheading: Removal of spent flowers. On non-dropping African Violets, this is generally done by pinching the flowers off as they turn brown and shrivel up.

Deborah: Rhapsodie variety. Large, standard African Violet (4-inch pot size) with semi-double, bi-color flowers. Flowers are blue and white. Leaves are medium green. Introduced 1997. More information.

Decennie: Optimara variety. Medium, standard African Violet (4-inch pot size) with frilled, red flowers and medium green leaves. Introduced 1988. (AVSA Reg. No. 6948) More information.

Degas: Optimara variety belonging to the Artist's Palette series. Named for the French impressionist painter, Edgar Degas. Medium, standard African Violet (4-inch pot size) with single, bi-color flowers. Flowers are red and white. Leaves are medium green. Introduced 1996. More information.

Dehiscence: On African Violets, that part of the flower cycle when the anthers open up to release pollen.

Delaware: Optimara variety. Medium, standard African Violet (4-inch pot size) with frilled, red flowers and medium green leaves. Introduced 1977. Improved 1988 and 1990. (AVSA Reg. No. 3153 and 6845) More information.

Den Haag: Optimara variety belonging to the World Traveler series. Extra large, standard African Violet (6-inch pot size) with frilled, blue flowers and medium green leaves. Introduced 1995. (AVSA Reg. No. 8308) More information.

Denise: Rhapsodie variety. Medium, standard African Violet (4-inch pot size) with single, bi-color flowers. Flowers are white with a burgundy center. Leaves are medium green. More information.

Denitrification: Loss of available nitrogen due to overwatering. When the soil is continually soggy, nitrates are converted into their elemental gas form (N2) which escapes into the atmosphere, thus providing no benefit to the plant.

Dentate: Leaf type. See Serrated.

Denver: Optimara variety. Small, standard African Violet (4-inch pot size) with single, white flowers and dark green, girl-type leaves. Introduced 1987. (AVSA Reg. No. 6556) More information.

Desiree: Holtkamp variety (Europe). Standard African Violet (4-inch pot size). Flowers are red and white stars. Leaves are dark green. Available in the U.S. as Kansas.

Devotion: Optimara variety belonging to the Victorian Charm series. Medium, standard African Violet (4-inch pot size) with single, purple flowers and variegated leaves. Introduced 1995. (AVSA Reg. No. 8309) More information.

Diamond: Optimara super miniature variety. See Little Diamond.

Diana: Rhapsodie variety. Large, standard African Violet (4-inch pot size) with single, red flowers and dark green leaves. More information.

Diatomaceous Earth: A fully inert, non-volatile substance sometimes recommended as an alternative to traditional chemical treatments for controlling a number of insects and other pests, including Soil Mealy Bugs. Diatomaceous Earth (DE) is made from the skeletal remains of diatoms, a microscopic form of algae. When processed into DE, these skeletal remains form razor-sharp particles which cut into the soft bodies of small insects. While controlling insects, DE does not harm African Violets.

Diazinon: Insecticide sometimes recommended for controlling Black Vine Weevils. Diazinon is classified for general use by the EPA.

Dicofol: Miticide sometimes recommended for controlling Mites known to feed on African Violets, including Broad Mites, Cyclamen Mites, Privet Mites and Spider Mites. Dicofol is classified for general use by the EPA.

Dicot: See Dicotyledon.

Dicotyledon: Also called dicot. An angiosperm which has two cotyledons (seed leaves). Mature dicotyledons develop leaves with a branching network of veins, in contrast to monocotyledons which normally have parallel veins. African Violets are dicotyledons.

Difficilis: See Saintpaulia difficilis.

Diffusion: One of three processes by which soil nutrients become available to African Violets and other plants. As nutrients are absorbed, a lower concentration is formed at the root interface. To even out the concentration throughout the soil, nutrients move from areas of higher concentration to areas of lower concentration around the roots. Also see Mass Flow and Root Interception.

Dimethoate: Insecticide sometimes used to control Mealy Bugs and other insect pests. However, Dimethoate is not recommended for use on African Violets, since it can damage the leaves and flowers. Dimethoate is classified for general use by the EPA.

Diplotricha: See Saintpaulia diplotricha.

Direct Toxicity Effect: See Toxicity Effect.

Disbudding: The removal of flower buds. Disbudding is sometimes done to enhance the treatment for certain insect pests, i.e., Thrips. Disbudding also done to help redirect an African Violet's energy from growing flowers to growing larger leaves, thus promoting the growth of overall plant size.

Division: Method of propagating a new plant from a multiple-crowned African Violet on which the crowns have a shared root system. Division involves pulling the crowns apart and cutting through the common root system, resulting in two or more complete plants ready to be potted. Also see Separation. African Violets may also be propagated by seed, leaf cutting, peduncle cutting, tissue culture and by rooting a sucker.

Dolly: Rhapsodie variety. Medium, standard African Violet (4-inch pot size) with frilled, bi-color flowers. Flowers are white with a wide, purple edge. Leaves are medium green. Introduced 1988. Improved 1995. (AVSA Reg. No. 6981 and 8342) More information.

Dolomite: Sometimes called dolomitic lime. Type of lime. Sometimes mixed with potting soil in order to increase the pH. Also see Calcium Carbonate.

Dolomitic Lime: See Dolomite.

Dominica: Optimara variety. Medium, standard African Violet (4-inch pot size). Flowers are blue stars with a white edge. Leaves are medium green. Introduced 1991. (AVSA Reg. No. 7483) More information.

Doris: Holtkamp variety (Europe). Small, standard African Violet (4-inch pot size) with frilled, pink flowers and medium green, girl-type leaves. Available in the U.S. as Nashville.

Dorrenbach, Martin: Founder of the greenhouse, in 1904, which would later be renamed Holtkamp Greenhouses. Father-in-law of Hermann Holtkamp.

Double: Bloom type. Describes an African Violet flower with at least two layers of petals. First developed from Blue Boy in 1939. Contrast with Single and Semi-double.

Double Potting: Method of providing leaf support to African Violets. The method involves placing the pot of an African Violet inside a larger pot and filling around the inner pot with soil. Done in this manner, the outer pot will provide support to the leaves. Also see Flared-Top Pot and Leaf Support Ring.

Drench: To thoroughly water. When growing African Violets, drenching is often used to wash away excess fertilizer salts or to correct a pH imbalance in the soil.

Dust: Pesticide formulation which is applied as a dust, i.e., dry, in contrast to emulsifiable concentrates, wettable powders and soluble powders which are applied wet. Dusts also differ from granules in that the active ingredient of a dust is mixed with a diluent, whereas the active ingredient of granules is mixed into the diluent so that it is absorbed into or coats the granules.

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