Lacy: Leaf type. See Ruffled.
Lambada: Optimara variety belonging to the Little Dancer series. Compact African Violet (3-inch pot size) with single, two-tone pink flowers and dark green leaves. Introduced 1997. More information.
Lamina: Leaf blade.
Lanai: Optimara variety. Standard African Violet (4-inch pot size) with semi-double, bi-color flowers. Flowers are purple with a white edge. Leaves are medium green (red reverse). Introduced 1987. Improved 1995. (AVSA Reg. No. 6563 and 8318) More information.
Lapis: Optimara super miniature variety. See Little Lapis.
Large: Description of standard plant size. Large, standard African Violets are 14 to 16 inches in diameter and are normally grown in 4-inch pots.
Large Pre-Finished: Describes a commercially-grown African Violet which has begun to bloom in its first flowering cycle. A standard, large pre-finished African Violet will normally be 31 to 33 weeks old and will have 5 to 7 open blooms. Also see Small Pre-Finished.
Larva: Immature stage of insects. Often appear worm-like. See Black Vine Weevils and Caterpillars.
Laurie: Rhapsodie variety. Standard African Violet (4-inch pot size). Flowers are two-tone pink stars. Leaves are dark green. Introduced 1987. (AVSA Reg. No. 6614) More information.
LD50: Lethal dose 50 percent. Refers to a rating system used to classify the toxicity of pesticides to humans. Specifically, the rating tells how much of a given pesticide must be administered to each memeber of a sample group to kill 50 percent of that group. Therefore, based on this system, the lower the rating, the more dangerous the pesticide is.
Leach: With regard to African Violets, to remove some substance from the soil by drenching it with water and letting it drain. This is most often done to flush out excess fertilizer salts, to remove excess elements which might be causing a nutrient imbalance or to correct an imbalance in the soil pH. For this, a quantity of five times the pot's volume is usually recommended.
Leader: Also called the neck or collar. The main stem of a plant. On African Violets, this is the part of the plant just below the leaves which connects to the roots.
Leaf: The part of a plant which extends from the petioles. On African Violets, they are either some shade of green or variegated, and most have at least some plant hairs growing from them. Collectively, the leaves are called foliage. The function of leaves is to provide photosynthesis, transpiration and respiration for the plant. The flat, thin, blade-like part of a leaf is called the leaf blade or lamina. The central vein of a leaf is called the midrib. The edge of a leaf is called the leaf margin. The green pigment of a leaf is called chlorophyll, which is contained in the chloroplasts of leaf cells. Also see Leaf Type.
Leaf Beetles: Insects known to feed on African Violets. Leaf Beetles measure 1/16 to 1/4 inch in length, and they can be found in many different colors and patterns. Their most distinctive trait is the damage they leave behind, i.e., small, round holes which begin at the edge of the leaves. More information.
Leaf Blade: Also called lamina. The flat, thin, blade-like part of a leaf.
Leaf Bleaching: On African Violets, a condition unique to those plants grown under artificial grow lights. Those parts of the leaves which are directly exposed to the artificial light turn a lighter shade of green than those parts which are not exposed to the light. More information.
Leaf Burn: See Leaf Scorch.
Leaf Color: On African Violets, describes a leaf's shade of green, usually stated as light, medium or dark green, though some descriptions are more detailed. A description of leaf color may also include variegated leaves.
Leaf Cutting: Also called mother leaf. Leaf used for leaf propagation. Typically, a leaf cutting includes the entire leaf blade plus about one to two inches of the petiole.
Leaf Debris: The remains of spent leaves which often accumulate on the surface of the soil. The presence of leaf and other plant debris may attract certain insects which feed on or take shelter beneath decaying plant matter. Such insects and related pests include Black Vine Weevils, Blackflies, Earwigs, Fungus Gnats, Isopods, Mushroom Flies, Sciarid Flies, Springtails and Symphylans.
Leaf Form: See Leaf Type.
Leaf Lifter: Any device, usually home-made, used to lift the leaves of African Violets. This is often necessary when working beneath the leaves, i.e., to remove leaf and flower debris from the soil or to add soil after potting down a neck.
Leaf Margin: Sometimes called margin. The outermost edge of a leaf.
Leaf Mealy Bugs: Sometimes called Foliar Mealy Bugs or Cottony Mealy Bugs. Insects known to feed on African Violets. Leaf Mealy Bugs measure 1/16 to 1/4 inch in length. They are coated with a white, powdery, wax-like substance which makes them look like specks of cotton clinging to the leaves and stems. If left untreated, Leaf Mealy Bugs will destroy an African Violet. Common species include Citrus Mealy Bugs, Citrophilus Mealy Bugs, Long-Tailed Mealy Bugs and Grape (or Bakers) Mealy Bugs. More information.
Leaf Nematodes: Aphelenchoides olesistus. Microscopic, unsegmented worms known to feed on African Violets. Leaf Nematodes enter African Violets through wounds or leaf pores (stomata), actually feeding from within the plants. The feeding activity of Leaf Nematodes causes stems to swell up and the underside of leaves to develop shiny, brown spots between the veins. In almost all cases, Leaf Nematodes are fatal. More information.
Leaf Pores: Stomata.
Leaf Propagation: Method of reproducing African Violets. Leaf propagation involves removing a leaf from a parent plant, along with one to two inches of the petiole. This is called a leaf cutting. This leaf cutting is placed stem-first (or heel-first) into potting soil, water or some other rooting medium. Within 40 to 50 days, a plantlet will begin to emerge, complete with its own root system. This method produces a variety that is the same as the parent plant from which the leaf cutting came. African Violets may also be propagated by seed, division (or separation), peduncle cutting or by rooting a sucker.
Leaf Ring: See Leaf Support Ring.
Leaf Rot: Also called Petiole Rot. A condition caused by the application of too much fertilizer. Because normal watering is unable to leach them out, fertilizer salts begin to accumulate in the soil and around the rim of the pot. Where leaves and stems come in contact with the pot, they begin to develop lesions. Eventually, these leaves and stems will wilt and turn mushy, i.e., they rot. More information.
Leaf Scorch: Sometimes called leaf burn. A condition analogous to sunburn. African Violets suffer leaf scorch when exposed to too much direct sunlight or when placed too close to grow lights. Symptoms appear as dry, dark patches on the upperside of the leaves. More information.
Leaf Shape: Description of the shape of an African Violet leaf. Often included under the description of leaf type. Specific leaf shapes include heart-shaped, holly, longifolia, ovate, pointed, round, serrated and truncate.
Leaf Shoot: See Shoot.
Leaf Spots: Generally, any unusual spots found on the leaves of African Violets, such as those caused by getting water on the leaves. However, the term is often reserved for those spots specifically caused by bacteria. See Bacterial Leaf Blight. Also see Ring Spot.
Leaf Stalk: See Petiole.
Leaf Start Mix: See Rooting Medium.
Leaf Stem: See Petiole.
Leaf Support Ring: A ring, often made of plastic, which attaches to a pot in order to support the leaves of African Violets. By supporting the leaves, a leaf support ring encourages symmetry and helps train the leaves to grow out rather than down and over the pot. Standard leaf support rings fit pot sizes up to seven inches and accommodate African Violets with diameters up to 18 inches. Other methods for providing leaf support are double potting and using a flared-top pot.
Leaf Tip: Also called apex. The tip of a leaf or the point on a leaf furthest from the stem.
Leaf Tip Burn: Condition which describes an African Violet leaf which has become dry and brown on the tip. Leaf tip burn is a form of necrosis and is, most often, caused by a nutrient imbalance such as an excess of boron or nitrogen, or a deficiency of calcium, molybdenum or potassium. Also see Leaf Scorch.
Leaf Type: Also called leaf form. Description of the physical characteristics of an African Violet leaf. A leaf type denotes some combination of a leaf's color, shape, size, texture and amount of hair. Specific leaf types include bustleback, crenate, holly, longifolia, oak leaf, ovate, plain, pointed, quilted, red reverse, round, ruffled, scalloped, serrated, spooned, strawberry, supreme, tailored, trumpet, truncate and variegated.
|A B C D E F G H I J K L M N O P Q R S T U V W X Y Z|
|Optimara Main Page|
|Doctor Optimara | Optimara Field Guide | Contact Optimara|
Copyright 1999 Optimara/Holtkamp Greenhouses, Inc. Nashville, Tennessee. Optimara and the Optimara logo are registered trademarks of International Plant Breeding, A.G., Switzerland.